text: Small craters of special interest (for example, visited by lunar missions) receive human first names (Robert, José, Louise etc.). One of the biggest lunar craters, Apollo, is named after Apollo missions. Many smaller craters inside and near it bear the names of deceased American astronauts, and many craters inside and near Mare Moscoviense bear the names of deceased Soviet cosmonauts. Besides this, in 1970 twelve craters were named after twelve living astronauts (6 Soviet and 6 American).

text: Small craters of special interest (for example, visited by lunar missions) receive human first names (Robert, José, Louise etc.). One of the biggest lunar craters,

entity_name: Apollo (crater)

text: Apollo

text: , is named after

entity_name: Apollo program

text: Apollo missions

text: . Many smaller craters inside and near it bear the names of deceased American astronauts, and many craters inside and near

entity_name: Mare Moscoviense

text: Mare Moscoviense

text: bear the names of deceased Soviet cosmonauts. Besides this, in 1970 twelve craters were named after twelve living astronauts (6 Soviet and 6 American).

text: The only task left for the crew at this point was to perform the Trans-Earth Injection (TEI), which was scheduled for 2½ hours after the end of the television transmission. The TEI was the most critical burn of the flight, as any failure of the SPS to ignite would strand the crew in lunar orbit, with little hope of escape. As with the previous burn, the crew had to perform the maneuver above the far side of the Moon, out of contact with Earth.

text: The only task left for the crew at this point was to perform the

entity_name: Trans-Earth injection

text: Trans-Earth Injection

text: (TEI), which was scheduled for 2½ hours after the end of the television transmission. The TEI was the most critical burn of the flight, as any failure of the SPS to ignite would strand the crew in lunar orbit, with little hope of escape. As with the previous burn, the crew had to perform the maneuver above the far side of the Moon, out of contact with Earth.

text: The fourth season of the Sailor Moon anime series, titled , was produced by Toei Animation and directed by Kunihiko Ikuhara. Like the rest of the series, it adapts the manga series by Naoko Takeuchi and follows the adventures of Usagi Tsukino and her friends. The series is divided into two story arcs. The first arc for 22 episodes depicts a deity known as Pegasus, entering Chibiusa's dreams to flee from the Dead Moon Circus; they desire to kill him for world domination. The second arc for 17 episodes depicts the arrival of the Amazoness Quartet, a group of enemies who dreams to stay forever as children, as well as Queen Nehelenia, the "Dead Moon Queen" and leader of the Dead Moon Circus invasion of Earth.

text: The fourth season of the

entity_name: Sailor Moon

text: Sailor Moon

text: anime series, titled , was produced by

entity_name: Toei Animation

text: Toei Animation

text: and directed by

entity_name: Kunihiko Ikuhara

text: Kunihiko Ikuhara

text: . Like the rest of the series, it adapts the manga series by

entity_name: Naoko Takeuchi

text: Naoko Takeuchi

text: and follows the adventures of

entity_name: Sailor Moon (character)

text: Usagi Tsukino

text: and her friends. The series is divided into two

entity_name: Story arc

text: story arc

text: s. The first arc for 22 episodes depicts a deity known as Pegasus, entering Chibiusa's dreams to flee from the

entity_name: Dead Moon Circus

text: Dead Moon Circus

text: ; they desire to kill him for world domination. The second arc for 17 episodes depicts the arrival of the Amazoness Quartet, a group of enemies who dreams to stay forever as children, as well as Queen Nehelenia, the "Dead Moon Queen" and leader of the Dead Moon Circus invasion of Earth.

text: Goddard is a lunar crater that is located along the eastern limb of the Moon, and so is visible from the edge from Earth. It is best viewed during favorable librations when the orientation of the Moon brings it further into sight. The crater is located in the Mare Marginis, to the northeast of the prominent crater Neper. Ibn Yunus, a crater remnant, is attached to the southeastern rim, and is partly overlaid by Goddard. To the northeast is Al-Biruni.

text: Goddard is a

entity_name: Moon

text: lunar

entity_name: Impact crater

text: crater

text: that is located along the eastern limb of the

text: Moon

text: , and so is visible from the edge from

entity_name: Earth

text: Earth

text: . It is best viewed during favorable

entity_name: Libration

text: libration

text: s when the orientation of the Moon brings it further into sight. The crater is located in the

entity_name: Mare Marginis

text: Mare Marginis

text: , to the northeast of the prominent crater

entity_name: Neper (crater)

text: Neper

entity_name: Ibn Yunus (crater)

text: Ibn Yunus

text: , a crater remnant, is attached to the southeastern rim, and is partly overlaid by Goddard. To the northeast is

entity_name: Al-Biruni (crater)

text: Al-Biruni

text: Having a mean density of 3,346.4 kg/m³, the Moon is a differentiated body, being composed of a geochemically distinct crust, mantle, and core. This structure is believed to have resulted from the fractional crystallization of a magma ocean shortly after its formation about 4.5 billion years ago. The energy required to melt the outer portion of the Moon is commonly attributed to a giant impact event that is postulated to have formed the Earth-Moon system, and the subsequent reaccretion of material in Earth orbit. Crystallization of this magma ocean would have given rise to a mafic mantle and a plagioclase-rich crust.

text: Having a

entity_name: Arithmetic mean

text: mean

text: density of 3,346.4

entity_name: Kilogram per cubic metre

text: , the

text: Moon

text: is a

entity_name: Planetary differentiation

text: differentiated

text: body, being composed of a

entity_name: Geochemistry

text: geochemically

text: distinct

entity_name: Crust (geology)

text: crust

entity_name: Mantle (geology)

text: mantle

text: , and core. This structure is believed to have resulted from the

entity_name: Fractional crystallization (geology)

text: fractional crystallization

text: of a

entity_name: Lunar magma ocean

text: magma ocean

text: shortly after its formation about 4.5 billion years ago. The energy required to melt the outer portion of the Moon is commonly attributed to a

entity_name: Giant-impact hypothesis

text: giant impact

text: event that is postulated to have formed the Earth-Moon system, and the subsequent reaccretion of material in Earth orbit. Crystallization of this magma ocean would have given rise to a mafic mantle and a

entity_name: Plagioclase

text: plagioclase

text: -rich crust.

text: A permanent asymmetric moon dust cloud exists around the Moon, created by small particles from comets. Estimates are 5 tons of comet particles strike the Moon's surface each 24 hours. The particles strike the Moon's surface ejecting moon dust above the Moon. The dust stays above the Moon approximately 10 minutes, taking 5 minutes to rise, and 5 minutes to fall. On average, 120 kilograms of dust are present above the Moon, rising to 100 kilometers above the surface. The dust measurements were made by LADEE's Lunar Dust EXperiment (LDEX), between 20 and 100 kilometers above the surface, during a six-month period. LDEX detected an average of one 0.3 micrometer moon dust particle each minute. Dust particle counts peaked during the Geminid, Quadrantid, Northern Taurid, and Omicron Centaurid meteor showers, when the Earth, and Moon, pass through comet debris. The cloud is asymmetric, more dense near the boundary between the Moon's dayside and nightside.

text: A permanent asymmetric

entity_name: Lunar soil

text: moon dust

text: cloud exists around the Moon, created by small particles from

entity_name: Comet

text: comets

text: . Estimates are 5 tons of comet particles strike the Moon's surface each 24 hours. The particles strike the Moon's surface ejecting moon dust above the Moon. The dust stays above the Moon approximately 10 minutes, taking 5 minutes to rise, and 5 minutes to fall. On average, 120 kilograms of dust are present above the Moon, rising to 100 kilometers above the surface. The dust measurements were made by

entity_name: Lunar Atmosphere and Dust Environment Explorer

text: LADEE

text: 's Lunar Dust EXperiment (LDEX), between 20 and 100 kilometers above the surface, during a six-month period. LDEX detected an average of one 0.3 micrometer moon dust particle each minute. Dust particle counts peaked during the

entity_name: Geminids

text: Geminid

entity_name: Quadrantids

text: Quadrantid

entity_name: Taurids

text: Northern Taurid

text: , and

entity_name: Omicron Centaurids

text: Omicron Centaurid

entity_name: Meteor shower

text: meteor shower

text: s, when the Earth, and Moon, pass through comet debris. The cloud is asymmetric, more dense near the boundary between the Moon's dayside and nightside.

text: Swasey is a small lunar crater that lies along the eastern limb of the Moon. It lies near the southeastern edge of the Mare Smythii, to the west of the walled plain Hirayama. About one crater diameter to the northeast is Hume, and to the southwest is the merged crater pair of Kao and Helmert.

text: Swasey is a small

text: lunar

text: crater

text: that lies along the eastern limb of the

text: Moon

text: . It lies near the southeastern edge of the

entity_name: Mare Smythii

text: Mare Smythii

text: , to the west of the walled plain

entity_name: Hirayama (crater)

text: Hirayama

text: . About one crater diameter to the northeast is

entity_name: Hume (crater)

text: Hume

text: , and to the southwest is the merged crater pair of

entity_name: Kao (crater)

text: Kao

text: and

entity_name: Helmert (crater)

text: Helmert

text: The Soviet Union sent the first spacecraft to the vicinity of the Moon, the robotic vehicle Luna 1, on January 4, 1959.  It passed within  of the Moon's surface, but did not achieve lunar orbit.  Luna 3, launched on October 4, 1959, was the first robotic spacecraft to complete a circumlunar free return trajectory, still not a lunar orbit, but a figure-8 trajectory which swung around the far side of the Moon and returned to the Earth. This craft provided the first pictures of the far side of the Lunar surface.

text: The

entity_name: Soviet Union

text: Soviet Union

text: sent the first spacecraft to the vicinity of the Moon, the robotic vehicle

entity_name: Luna 1

text: Luna 1

text: , on January 4, 1959.  It passed within  of the Moon's surface, but did not achieve lunar orbit.

entity_name: Luna 3

text: Luna 3

text: , launched on October 4, 1959, was the first robotic spacecraft to complete a

entity_name: Circumlunar trajectory

text: circumlunar

entity_name: Free return trajectory

text: free return trajectory

text: , still not a lunar orbit, but a figure-8 trajectory which swung around the

entity_name: Far side of the Moon

text: far side of the Moon

text: and returned to the Earth. This craft provided the first pictures of the far side of the Lunar surface.

text: Safely on the Moon, they explore the lunar surface, reporting back by radio how their view of the Earth looks contrasted against the black lunar sky; one crew member photographs another pretending to hold up the Earth like a modern Atlas. The story takes a serious turn when they calculate the mass needed to lighten their spaceship in the Moon's one-sixth gravity in order to get home safely with their remaining fuel. No matter how much non-critical equipment they remove and leave on the lunar surface, the hard numbers radioed from Earth continue to point to one conclusion: Someone will have to stay behind on the Moon if the other three crew are to return safely to Earth. With time running out for their return launch window, the crew engineers their way home. They first jettison the ship's heavy radio equipment, losing contact with Earth, and finally their sole remaining space suit. An oxygen tank is used as a tethered, suspended weight to pull the space suit outside through the open airlock, which is then remotely closed and resealed. Their critical take-off weight finally achieved, and with all her crew safely aboard, Luna blasts off from the Moon for home.

text: Safely on the Moon, they explore the lunar surface, reporting back by radio how their view of the Earth looks contrasted against the black lunar sky; one crew member photographs another pretending to hold up the Earth like a modern

entity_name: Atlas (mythology)

text: Atlas

text: . The story takes a serious turn when they calculate the mass needed to lighten their spaceship in the Moon's one-sixth gravity in order to get home safely with their remaining fuel. No matter how much non-critical equipment they remove and leave on the lunar surface, the hard numbers radioed from Earth continue to point to one conclusion: Someone will have to stay behind on the Moon if the other three crew are to return safely to Earth. With time running out for their return launch window, the crew engineers their way home. They first jettison the ship's heavy radio equipment, losing contact with Earth, and finally their sole remaining space suit. An oxygen tank is used as a tethered, suspended weight to pull the space suit outside through the open

entity_name: Airlock

text: airlock

text: , which is then remotely closed and resealed. Their critical take-off weight finally achieved, and with all her crew safely aboard, Luna blasts off from the Moon for home.

text: The most obvious effect of tidal forces is to cause two bulges in the Earth's oceans, one on the side facing the Moon and the other on the side opposite. This results in elevated sea levels called ocean tides. As the Earth spins on its axis, one of the ocean bulges (high tide) is held in place "under" the Moon, while another such tide is opposite. As a result, there are two high tides, and two low tides in about 24 hours. Since the Moon is orbiting the Earth in the same direction of the Earth's rotation, the high tides occur about every 12 hours and 25 minutes; the 25 minutes is due to the Moon's time to orbit the Earth. The Sun has the same tidal effect on the Earth, but its forces of attraction are only 40% that of the Moon's; the Sun's and Moon's interplay is responsible for spring and neap tides. If the Earth was a water world (one with no continents) it would produce a tide of only one meter, and that tide would be very predictable, but the ocean tides are greatly modified by other effects: the frictional coupling of water to Earth's rotation through the ocean floors, the inertia of water's movement, ocean basins that grow shallower near land, the sloshing of water between different ocean basins. As a result, the timing of the tides at most points on the Earth is a product of observations that are explained, incidentally, by theory.

text: The most obvious effect of tidal forces is to cause two bulges in the Earth's oceans, one on the side facing the Moon and the other on the side opposite. This results in elevated sea levels called

entity_name: Tide

text: ocean tides

text: . As the Earth spins on its axis, one of the ocean bulges (high tide) is held in place "under" the Moon, while another such tide is opposite. As a result, there are two high tides, and two low tides in about 24 hours. Since the Moon is orbiting the Earth in the same direction of the Earth's rotation, the high tides occur about every 12 hours and 25 minutes; the 25 minutes is due to the Moon's time to orbit the Earth. The Sun has the same tidal effect on the Earth, but its forces of attraction are only 40% that of the Moon's; the Sun's and Moon's interplay is responsible for

entity_section: Range variation: springs and neaps

text: spring and neap tides

text: . If the Earth was a water world (one with no continents) it would produce a tide of only one meter, and that tide would be very predictable, but the ocean tides are greatly modified by other effects: the frictional coupling of water to Earth's rotation through the ocean floors, the

entity_name: Inertia

text: inertia

text: of water's movement, ocean basins that grow shallower near land, the sloshing of water between different ocean basins. As a result, the timing of the tides at most points on the Earth is a product of observations that are explained, incidentally, by theory.

text: Armed with the knowledge of shock-metamorphic features, Carlyle S. Beals and colleagues at the Dominion Astrophysical Observatory in Victoria, British Columbia, Canada and Wolf von Engelhardt of the University of Tübingen in Germany began a methodical search for impact craters. By 1970, they had tentatively identified more than 50. Although their work was controversial, the American Apollo Moon landings, which were in progress at the time, provided supportive evidence by recognizing the rate of impact cratering on the Moon. Because the processes of erosion on the Moon are minimal, craters persist almost indefinitely.  Since the Earth could be expected to have roughly the same cratering rate as the Moon, it became clear that the Earth had suffered far more impacts than could be seen by counting evident craters.

text: Armed with the knowledge of shock-metamorphic features,

entity_name: Carlyle Smith Beals

text: Carlyle S. Beals

text: and colleagues at the

entity_name: Dominion Astrophysical Observatory

text: Dominion Astrophysical Observatory

text: in

entity_name: Victoria, British Columbia

text: Victoria, British Columbia

entity_name: Canada

text: Canada

text: and

entity_name: Wolf von Engelhardt

text: Wolf von Engelhardt

text: of the

entity_name: University of Tübingen

text: University of Tübingen

text: in

entity_name: Germany

text: Germany

text: began a methodical search for impact craters. By 1970, they had tentatively identified more than 50. Although their work was controversial, the American

text: Apollo

text: Moon landings, which were in progress at the time, provided supportive evidence by recognizing the rate of impact cratering on the

text: Moon

text: . Because the processes of erosion on the Moon are minimal, craters persist almost indefinitely.  Since the Earth could be expected to have roughly the same cratering rate as the Moon, it became clear that the Earth had suffered far more impacts than could be seen by counting evident craters.

text: They photograph the lunar surface as they begin to land on the Moon, but more fuel is wasted when they try to avoid a large, deep canyon on their final landing approach. The spaceship lands out of direct line-of-sight of the Earth, so they are unable to report back via radio. The estimates of their remaining fuel supply indicates they lack enough fuel to return home safely. Admiral Bowles takes the view their safe return is irrelevant. All that matters now is that they claim the Moon in the name of the United States of America and make radio contact with Earth to report this fact. He suggests using their remaining fuel to make a brief flight into direct sight of Earth to report their claim, sacrificing themselves in the process for the greater good. The other crew members, however, prefer to try to return home, if at all possible.

text: They photograph the

entity_name: Geology of the Moon

entity_section: Lunar landscape

text: lunar surface

text: as they begin to land on the Moon, but more fuel is wasted when they try to avoid a large, deep canyon on their final landing approach. The spaceship lands out of direct

entity_name: Sightline

text: line-of-sight

text: of the Earth, so they are unable to report back via

entity_name: Radio

text: radio

text: . The estimates of their remaining fuel supply indicates they lack enough fuel to return home safely. Admiral Bowles takes the view their safe return is irrelevant. All that matters now is that they claim the Moon in the name of the

entity_name: United States

text: United States of America

text: and make radio contact with Earth to report this fact. He suggests using their remaining fuel to make a brief flight into direct sight of Earth to report their claim, sacrificing themselves in the process for the greater good. The other crew members, however, prefer to try to return home, if at all possible.

text: Being the largest body in the asteroid belt, Ceres could become the main base and transport hub for future asteroid mining infrastructure, allowing mineral resources to be transported to Mars, the Moon, and Earth. Because of its small escape velocity combined with large amounts of water ice, it also could serve as a source of water, fuel, and oxygen for ships going through and beyond the asteroid belt. Transportation from Mars or the Moon to Ceres would be even more energy-efficient than transportation from Earth to the Moon.

text: Being the largest body in the asteroid belt, Ceres could become the main base and transport hub for future asteroid mining infrastructure, allowing mineral resources to be transported to

entity_name: Mars

text: Mars

text: , the

text: Moon

text: , and Earth. Because of its small escape velocity combined with large amounts of water ice, it also could serve as a source of water, fuel, and oxygen for ships going through and beyond the asteroid belt. Transportation from Mars or the Moon to Ceres would be even more energy-efficient than transportation from Earth to the Moon.

text: While the orbit of a satellite around the Sun was empirically discovered by Kepler and theoretically proven by Newton to be an ellipse, at the time when the United States was interested in going to the Moon, there was no such solution known for the shape of a satellite orbiting regularly around two objects, such as a spacecraft going between the Earth and the Moon.  This is a special case of the infamous Three Body Problem, for which a  general analytical solution is not known because of its complexity of solving the effect of three bodies which all pull on each other while moving, a total of six interactions.  However the case of an Earth-Moon satellite can be simplified to four interactions, because although the three objects gravitationally all pull on each other, the effect of the spacecraft's gravity upon the motion of the vastly more massive Earth and Moon is practically non-existent.  Arenstorf found a stable orbit for a spacecraft orbiting between the Earth and Moon, shaped like an '8' with the Earth or Moon located inside each loop of the '8'.  This orbit is the basis of a path going to the Moon from the Earth, such as the United States Apollo program.  For a permanent presence on the Moon, it would be the path of what Arenstorf calls a 'Space Bus', a ferry which could regularly orbit supplies and people between the Earth and Moon without directly expending fuel.   By staying on the Arenstorf orbit, lunar astronauts automatically return to Earth.  Before leaving NASA at the first Moon Landing, Arenstorf mapped out an emergency rescue orbit, which was used in the Apollo 13 incident, in which a catastrophic malfunction forced aborting the Moon landing, but the astronauts ultimately returned safely to Earth without a major course adjustment.

text: While the orbit of a satellite around the Sun was empirically discovered by Kepler and theoretically proven by Newton to be an

entity_name: Ellipse

text: ellipse

text: , at the time when the United States was interested in going to the Moon, there was no such solution known for the shape of a satellite orbiting regularly around two objects, such as a spacecraft going between the Earth and the Moon.  This is a special case of the infamous

entity_name: Three-body problem

text: Three Body Problem

text: , for which a  general analytical solution is not known because of its complexity of solving the effect of three bodies which all pull on each other while moving, a total of six interactions.  However the case of an Earth-Moon satellite can be simplified to four interactions, because although the three objects gravitationally all pull on each other, the effect of the spacecraft's gravity upon the motion of the vastly more massive Earth and Moon is practically non-existent.  Arenstorf found a stable orbit for a spacecraft orbiting between the Earth and Moon, shaped like an '8' with the Earth or Moon located inside each loop of the '8'.  This orbit is the basis of a path going to the Moon from the Earth, such as the United States

text: Apollo program

text: .  For a permanent presence on the Moon, it would be the path of what Arenstorf calls a 'Space Bus', a ferry which could regularly orbit supplies and people between the Earth and Moon without directly expending fuel.   By staying on the Arenstorf orbit, lunar astronauts automatically return to Earth.  Before leaving NASA at the first Moon Landing, Arenstorf mapped out an emergency rescue orbit, which was used in the

entity_name: Apollo 13

text: Apollo 13

text: incident, in which a catastrophic malfunction forced aborting the Moon landing, but the astronauts ultimately returned safely to Earth without a major course adjustment.

text: Lunar scientists were particularly interested in rocks that had higher concentrations of samarium, uranium, thorium, potassium and phosphorus. They gave these rocks the acronym KREEP (potassium (atomic symbol K), rare earth elements (REE), and phosphorus (P)). The gamma-ray spectrometer was designed to detect these types of rocks. They had been found at the Apollo 12 and Apollo 14 landing sites but not at the Apollo 11 site, which was about 1,000 km to the east. At the time of the Apollo 15 scientists were interested in whether KREEP rocks were found all over the Moon or just in the region around 12 and 14. It is believed that KREEPs represent the last chemical remnants of that magma ocean after the lunar crust formed. KREEPs floated to the surface because their component elements are "incompatible", that is, they did not incorporate into compact crystal structures. Results from Lunar Prospector's gamma ray spectrometer shows that KREEP-containing rocks are concentrated in the Mare Imbrium rim, the near side maria and highlands near Imbrium and the Mare Ingenii South Pole-Aitken basin and are distributed at a lower level in the highlands. The distribution seen by Lunar Prospector supports the idea that the impact which formed Mare Imbrium excavated KREEP-rich rocks and ejected them over the Moon and the South Pole-Aitken basin impact also exposed KREEP-rich material.

text: Lunar scientists were particularly interested in rocks that had higher concentrations of

entity_name: Samarium

text: samarium

entity_name: Uranium

text: uranium

entity_name: Thorium

text: thorium

text: potassium

text: and

text: phosphorus

text: . They gave these rocks the

text: acronym

text: KREEP

text: (potassium (atomic symbol K), rare earth elements (REE), and phosphorus (P)). The gamma-ray spectrometer was designed to detect these types of rocks. They had been found at the

text: Apollo 12

text: and

text: Apollo 14

text: landing sites but not at the

text: Apollo 11

text: site, which was about 1,000 km to the east. At the time of the Apollo 15 scientists were interested in whether KREEP rocks were found all over the Moon or just in the region around 12 and 14. It is believed that KREEPs represent the last chemical remnants of that magma ocean after the lunar crust formed. KREEPs floated to the surface because their component elements are "incompatible", that is, they did not incorporate into compact crystal structures. Results from

text: Lunar Prospector

text: 's gamma ray

text: spectrometer

text: shows that KREEP-containing rocks are concentrated in the

text: Mare Imbrium

text: rim, the near side

text: maria

text: and highlands near Imbrium and the

text: Mare Ingenii

text: South Pole-Aitken basin

text: and are distributed at a lower level in the highlands. The distribution seen by Lunar Prospector supports the idea that the impact which formed Mare Imbrium excavated KREEP-rich rocks and ejected them over the Moon and the South Pole-Aitken basin impact also exposed KREEP-rich material.

text: Note that the cow is able to jump over the Moon with ease because the Man in the Moon has temporarily brought it down to Earth.

text: Note that the cow is able to jump over the

text: Moon

text: with ease because the Man in the Moon has temporarily brought it down to

text: Earth

text: Because the gravitational field created by the Moon weakens with distance from the Moon, it exerts a slightly stronger than average force on the side of the Earth facing the Moon, and a slightly weaker force on the opposite side. The Moon thus tends to "stretch" the Earth slightly along the line connecting the two bodies. The solid Earth deforms a bit, but ocean water, being fluid, is free to move much more in response to the tidal force, particularly horizontally.  As the Earth rotates, the magnitude and direction of the tidal force at any particular point on the Earth's surface change constantly; although the ocean never reaches equilibrium—there is never time for the fluid to "catch up" to the state it would eventually reach if the tidal force were constant—the changing tidal force nonetheless causes rhythmic changes in sea surface height.

text: The topography of the Moon has been measured with laser altimetry and stereo image analysis. Its most visible topographic feature is the giant far-side South Pole–Aitken basin, some  in diameter, the largest crater on the Moon and the second-largest confirmed impact crater in the Solar System. At  deep, its floor is the lowest point on the surface of the Moon. The highest elevations of the Moon's surface are located directly to the northeast, and it has been suggested might have been thickened by the oblique formation impact of the South Pole–Aitken basin. Other large impact basins, such as Imbrium, Serenitatis, Crisium, Smythii, and Orientale, also possess regionally low elevations and elevated rims. The far side of the lunar surface is on average about  higher than that of the near side.

text: The

text: topography of the Moon

text: has been measured with

text: laser altimetry

text: and

text: stereo image analysis

text: . Its most visible

text: topographic feature

text: is the giant far-side

text: South Pole–Aitken basin

text: , some  in diameter, the largest crater on the Moon and the second-largest confirmed impact

entity_name: List of largest craters in the Solar System

text: crater in the Solar System

text: . At  deep, its floor is the lowest point on the surface of the Moon. The highest elevations of the Moon's surface are located directly to the northeast, and it has been suggested might have been thickened by the oblique formation impact of the South Pole–Aitken basin. Other large impact basins, such as

text: Imbrium

text: Serenitatis

text: Crisium

text: Smythii

text: , and

text: Orientale

text: , also possess regionally low elevations and elevated rims. The far side of the lunar surface is on average about  higher than that of the near side.

text: Interpretation of the origin of the smooth plains is difficult but significant, because it bears directly on the internal constitution and thermal history of Mercury. Like the lunar maria, the smooth plains occur on the floors of large craters and basins, and the broad swath of plains around Caloris finds an analogy with Oceanus Procellarum around Imbrium on the Moon. However, the Caloris plains differ from the maria in having no observed positive-relief volcanic features such as those sparsely scattered on the lunar maria. The absence of sharp albedo differences between the smooth plains and the older terrain (Hapke and others, 1975), compared with the distinct difference in albedo between the lunar maria and highlands, may be more indicative of composition than of origin of the rocks. On the basis of distribution and volume, Strom and others argued that in most areas the smooth plains consist of extensive sheets of basic lava similar to the lunar maria. Schultz (1977), studying modified impact craters, also argued in favor of volcanism. On the other hand, Wilhelms pointed out that the lunar light plains could also serve as an analog of the mercurian smooth plains: Apollo 16 samples indicate that lunar light plains consist of cataclastic breccia and impact melt, interpreted as being emplaced by large impact events (James, 1977). Wilhelms, therefore, proposed that the smooth plains on Mercury may be related to the Caloris impact directly, as breccias and impact melts, rather than as lavas. However, the light plains on the Moon are nowhere so well developed or extensive as the plains around Caloris, and if Wilhelms’ explanation is correct, considerable differences must exist between large impact events on the Moon and Mercury. Most likely, large parts of the smooth plains are of volcanic origin, although in some areas they may be of impact-melt origin.

text: Interpretation of the origin of the smooth plains is difficult but significant, because it bears directly on the internal constitution and thermal history of Mercury. Like the

text: lunar maria

text: , the smooth plains occur on the floors of large craters and basins, and the broad swath of plains around Caloris finds an analogy with

text: Oceanus Procellarum

text: around Imbrium on the Moon. However, the Caloris plains differ from the maria in having no observed positive-relief volcanic features such as those sparsely scattered on the lunar maria. The absence of sharp albedo differences between the smooth plains and the older terrain (Hapke and others, 1975), compared with the distinct difference in albedo between the lunar maria and highlands, may be more indicative of composition than of origin of the rocks. On the basis of distribution and volume, Strom and others argued that in most areas the smooth plains consist of extensive sheets of basic lava similar to the lunar maria. Schultz (1977), studying modified impact craters, also argued in favor of volcanism. On the other hand, Wilhelms pointed out that the lunar light plains could also serve as an analog of the mercurian smooth plains:

text: Apollo 16

text: samples indicate that lunar light plains consist of

text: cataclastic breccia

text: and

text: impact melt

text: , interpreted as being emplaced by large impact events (James, 1977). Wilhelms, therefore, proposed that the smooth plains on Mercury may be related to the Caloris impact directly, as breccias and impact melts, rather than as lavas. However, the light plains on the Moon are nowhere so well developed or extensive as the plains around Caloris, and if Wilhelms’ explanation is correct, considerable differences must exist between large impact events on the Moon and Mercury. Most likely, large parts of the smooth plains are of volcanic origin, although in some areas they may be of impact-melt origin.

text: A more ambitious project called the "Aristarchus Campaign" was conducted during the Lunar Eclipse of 15 April 2014. During this event, participants were invited to record a series of 5 digital photographs from moonrise through culmination - the point of greatest altitude.The method took advantage of the fact that the Moon is actually closest to an observer when it is at its highest point in the sky, compared to when it is on the horizon. Although it appears that the Moon is biggest when it is near the horizon, the opposite is true. This phenomena is known as the moon illusion. The reason for the change in distance results from the fact that the distance from the center of the Moon to the center of Earth is nearly constant throughout the night, but an observer on the surface of Earth is actually 1 Earth radius from the center of Earth.  This offset brings them closest to the Moon when it is overhead.

text: A more ambitious project called the "Aristarchus Campaign" was conducted during the Lunar Eclipse of 15 April 2014. During this event, participants were invited to record a series of 5 digital photographs from moonrise through

text: culmination

text: - the point of greatest altitude.The method took advantage of the fact that the Moon is actually closest to an observer when it is at its highest point in the sky, compared to when it is on the horizon. Although it appears that the Moon is biggest when it is near the horizon, the opposite is true. This phenomena is known as the

text: moon illusion

text: . The reason for the change in distance results from the fact that the distance from the center of the Moon to the center of Earth is nearly constant throughout the night, but an observer on the surface of Earth is actually 1 Earth radius from the center of Earth.  This offset brings them closest to the Moon when it is overhead.

text: The astronauts are left for dead in space, but they fall through a black hole and land in Heaven. Leaving Heaven guided by the Holy Spirit in the form of a dove, they refuel and make it back to the Moon where they encounter some US astronauts. They then use a US space-based surveillance system to find the centre of the water theft conspiracy on Earth. The crew return to Earth and rescue a hostage scientist (Per Jensen's girlfriend) at the installation. They defeat an alien monster with a keg of beer in a manner similar to that in Jaws and escape the installation just in time as it is destroyed by a nuclear bomb, sent from the Moon.

text: The astronauts are left for dead in space, but they fall through a

text: black hole

text: and land in

text: Heaven

text: . Leaving Heaven guided by the

text: Holy Spirit

text: in the form of a dove, they refuel and make it back to the Moon where they encounter some US astronauts. They then use a US space-based surveillance system to find the centre of the water theft conspiracy on Earth. The crew return to Earth and rescue a hostage scientist (Per Jensen's girlfriend) at the installation. They defeat an alien monster with a keg of beer in a manner similar to that in

text: Jaws

text: and escape the installation just in time as it is destroyed by a nuclear bomb, sent from the Moon.

text: The moon of Narnia is larger than Earth's moon.

text: The moon of Narnia is larger than Earth's

text: moon

text: Also many moons, even those that do not orbit the Sun directly, often exhibit features in common with true planets. There are 19 moons in the Solar System that have achieved hydrostatic equilibrium and would be considered planets if only the physical parameters are considered.  Both Jupiter's moon Ganymede and Saturn's moon Titan are larger than Mercury, and Titan even has a substantial atmosphere, thicker than the Earth's. Moons such as Io and Triton demonstrate obvious and ongoing geological activity, and Ganymede has a magnetic field. Just as stars in orbit around other stars are still referred to as stars, some astronomers argue that objects in orbit around planets that share all their characteristics could also be called planets. Indeed, Mike Brown makes just such a claim in his dissection of the issue, saying:

text: Also many moons, even those that do not orbit the Sun directly, often exhibit features in common with true planets. There are 19 moons in the Solar System that have achieved hydrostatic equilibrium and would be considered planets if only the physical parameters are considered.  Both Jupiter's moon

text: Ganymede

text: and Saturn's moon

text: Titan

text: are larger than Mercury, and Titan even has a substantial atmosphere, thicker than the Earth's. Moons such as

text: Io

text: and

text: Triton

text: demonstrate obvious and ongoing geological activity, and Ganymede has a

text: magnetic field

text: . Just as

text: star

text: s in orbit around other stars are still referred to as stars, some astronomers argue that objects in orbit around planets that share all their characteristics could also be called planets. Indeed, Mike Brown makes just such a claim in his dissection of the issue, saying:

text: The band's follow-up album, Interiors, released on June 24, 1997, was much more polished. Tom Moon of Rolling Stone said that "what's most notable about Interiors...is the pure pop focus of these nuanced compositions." The lead single from Interiors, "The Day Brings", features Mike McCready from Pearl Jam on lead guitar. Interiors was met with poor sales, however the band saw its cult audience expand. The album was accompanied by a tour in the United States and Canada that same year, as well as a small tour in Australia and New Zealand in 1998.

text: The band's follow-up album,

text: Interiors

text: , released on June 24, 1997, was much more polished. Tom Moon of

text: Rolling Stone

text: said that "what's most notable about Interiors...is the pure

text: pop

text: focus of these nuanced compositions." The lead single from Interiors, "The Day Brings", features

text: Mike McCready

text: from

text: Pearl Jam

text: on lead

text: guitar

text: . Interiors was met with poor sales, however the band saw its cult audience expand. The album was accompanied by a tour in the

text: United States

text: and

text: Canada

text: that same year, as well as a small tour in

text: Australia

text: and

text: New Zealand

text: in 1998.

text: Perrine is a lunar crater that is located on the northern hemisphere on the far side of the Moon. It lies to the west of the large walled plain Landau, and to the northeast of the crater Charlier. To the north-northwest is the smaller Gullstrand.

text: Perrine is a

text: lunar

text: crater

text: that is located on the northern

text: hemisphere

text: on the

text: far side

text: of the

text: Moon

text: . It lies to the west of the large walled plain

text: Landau

text: , and to the northeast of the crater

text: Charlier

text: . To the north-northwest is the smaller

text: Gullstrand

text: An eclipse can only occur when the Moon is close to the plane of the orbit of the Earth, i.e. when its ecliptic latitude is small.  This happens when the Moon is near one of the two nodes of its orbit on the ecliptic at the time of the syzygy.  Of course, to produce an eclipse, the Sun must also be near a node at that time: the same node for a solar eclipse, or the opposite node for a lunar eclipse.

text: An eclipse can only occur when the Moon is close to the plane of the orbit of the Earth, i.e. when its

text: ecliptic latitude

text: is small.  This happens when the Moon is near one of the two

text: node

text: s of its orbit on the ecliptic at the time of the

text: syzygy

text: .  Of course, to produce an eclipse, the Sun must also be near a node at that time: the same node for a solar eclipse, or the opposite node for a lunar eclipse.

text: A colony in lunar orbit would avoid the extreme temperature swings of the Moon's surface. Since the orbital period in low-lunar orbit is only about two hours, heat would only radiate away from the colony for a short period of time. At the Lagrangian points one and two, the thermal environment would be even more stable as the Sun would be almost continuously visible. This increased solar duration would allow for an almost constant supply of power. Additionally, the colony could be made to spin as has been examined with designs similar to the O'Neill cylinder so as to provide Earth-like gravity. Various lunar orbits are possible such as a Lissajous orbit or a halo orbit. Due to the Moon's lumpy gravity, there exist only a small number of possible orbital inclinations for low lunar orbits. A satellite in such a frozen orbit could be at an inclination of 27°, 50°, 76°, or 86°.

text: A colony in lunar orbit would avoid the extreme temperature swings of the Moon's surface. Since the orbital period in low-lunar orbit is only about two hours, heat would only radiate away from the colony for a short period of time. At the

text: Lagrangian point

text: s one and two, the thermal environment would be even more stable as the Sun would be almost continuously visible. This increased solar duration would allow for an almost constant supply of power. Additionally, the colony could be made to spin as has been examined with designs similar to the

text: O'Neill cylinder

text: so as to provide Earth-like gravity. Various lunar orbits are possible such as a

text: Lissajous orbit

text: or a

text: halo orbit

text: . Due to the Moon's lumpy gravity, there exist only a small number of possible orbital inclinations for low lunar orbits. A satellite in such a

text: frozen orbit

text: could be at an inclination of 27°, 50°, 76°, or 86°.

text: Therefore, at most new moons the Earth passes too far north or south of the lunar shadow, and at most full moons the Moon misses the shadow of the Earth.  Also, at most solar eclipses the apparent angular diameter of the Moon is insufficient to fully obscure the solar disc, unless the Moon is near its perigee, i.e. closer to the Earth and apparently larger than average. In any case, the alignment must be close to perfect to cause an eclipse.

text: Therefore, at most new moons the Earth passes too far north or south of the lunar shadow, and at most full moons the Moon misses the shadow of the Earth.  Also, at most solar eclipses the apparent angular diameter of the Moon is insufficient to fully obscure the solar disc, unless the Moon is near its

text: perigee

text: , i.e. closer to the Earth and apparently larger than average. In any case, the alignment must be close to perfect to cause an eclipse.

text: Amundsen is a large lunar impact crater located near the south pole of the Moon, named after the Norwegian explorer Roald Amundsen. It lies along the southern lunar limb, and so is viewed from the side by an observer on the Earth. To the northwest is the crater Scott, a formation of similar dimensions that is named for another Antarctic explorer. Nobile is attached to the western rim.

text: Amundsen is a large lunar

text: impact crater

text: located near the south pole of the

text: Moon

text: , named after the Norwegian explorer

text: Roald Amundsen

text: . It lies along the southern lunar limb, and so is viewed from the side by an observer on the

text: Earth

text: . To the northwest is the crater

text: Scott

text: , a formation of similar dimensions that is named for another

text: Antarctic

text: explorer.

text: Nobile

text: is attached to the western rim.

text: Because the Solar System proved to be devoid of an Earth analog, the search has widened to extrasolar planets. Astrobiologists assert that Earth analogs would most likely be found in a stellar habitable zone, in which liquid water could exist, providing the conditions for supporting life. Some astrobiologists, such as Dirk Schulze-Makuch, estimated that a sufficiently massive natural satellite may form a habitable moon similar to Earth.

text: Because the

text: Solar System

text: proved to be devoid of an Earth analog, the search has widened to

text: extrasolar planet

text: s. Astrobiologists assert that Earth analogs would most likely be found in a stellar

text: habitable zone

text: , in which liquid water could exist, providing the conditions for supporting life. Some astrobiologists, such as

text: Dirk Schulze-Makuch

text: , estimated that a sufficiently massive

text: natural satellite

text: may form a

text: habitable moon

text: similar to Earth.

text: Earthlight, also known as earthshine, is the partial illumination of the dark portion of the moon's surface by light reflected from the Earth and from the Earth's airglow. It is also known as Earthshine (see Planetshine), the Moon's ashen glow, or the old Moon in the new Moon's arms.

text: Earthlight, also known as earthshine, is the partial illumination of the dark portion of the

text: moon

text: 's surface by light reflected from the Earth and from the Earth's

text: airglow

text: . It is also known as Earthshine (see

text: Planetshine

text: ), the Moon's ashen glow, or the old Moon in the new Moon's arms.

text: Anderson speculates that the true intention of the ICBM warning devices is to monitor the aliens, and that the devices are the source of the interference, only to discover something has destroyed them when they attempt to switch them off. Walker shows signs of a developing infection and he becomes increasingly paranoid. The mission cameras capture the rock samples moving around in the interior of Liberty, revealing that the aliens are camouflaged as moon rocks. Increasingly delusional, Walker attempts to destroy the cameras within Liberty, but he accidentally damages the system controls, causing Liberty to depressurize. Realizing the Soviet LK is their only source of oxygen, the pair travel towards the LK lander in their lunar rover. Walker causes the vehicle to crash as he runs away, believing he should not leave the moon because of the risk of spreading the infection to Earth.

text: Anderson speculates that the true intention of the ICBM warning devices is to monitor the aliens, and that the devices are the source of the interference, only to discover something has destroyed them when they attempt to switch them off. Walker shows signs of a developing infection and he becomes increasingly paranoid. The mission cameras capture the rock samples moving around in the interior of Liberty, revealing that the aliens are camouflaged as moon rocks. Increasingly delusional, Walker attempts to destroy the cameras within Liberty, but he accidentally damages the system controls, causing Liberty to depressurize. Realizing the Soviet LK is their only source of oxygen, the pair travel towards the LK lander in their

text: lunar rover

text: . Walker causes the vehicle to crash as he runs away, believing he should not leave the moon because of the risk of spreading the infection to Earth.

text: The moon's orbit isn't in the same plane as the Earth's orbit around the sun, but crosses it in two places. The moon crosses the ecliptic plane twice a month, once when it goes up above the plane, and again 15 or so days later when it goes back down below the ecliptic. These two locations are the ascending and descending lunar nodes. Solar and lunar eclipses will occur only when the moon is positioned near one of these nodes, because at other times the moon is either too high or too low for an eclipse to be noticed from earth. Some astronomical clocks keep track of the position of the lunar nodes with a long pointer that crosses the dial. This so-called dragon hand makes one complete rotation around the ecliptic dial every 19 years. When the dragon hand and the new moon coincide, the moon is on the same plane as the earth and sun, and so there is every chance that an eclipse will be visible from somewhere on earth.

text: The moon's orbit isn't in the same plane as the Earth's orbit around the sun, but crosses it in two places. The moon crosses the ecliptic plane twice a month, once when it goes up above the plane, and again 15 or so days later when it goes back down below the ecliptic. These two locations are the ascending and descending

text: lunar nodes

text: . Solar and lunar eclipses will occur only when the moon is positioned near one of these nodes, because at other times the moon is either too high or too low for an eclipse to be noticed from earth. Some astronomical clocks keep track of the position of the lunar nodes with a long pointer that crosses the dial. This so-called dragon hand makes one complete rotation around the ecliptic dial every 19 years. When the dragon hand and the new moon coincide, the moon is on the same plane as the earth and sun, and so there is every chance that an eclipse will be visible from somewhere on earth.

text: Jonson opens his masque with a conversation among two heralds, a printer, a chronicler, and a factor (a kind of columnist or correspondent). All are in some sense in the news business, though their approaches differ; the traditional heralds are startled by the capitalist assumptions of the printer, who asks them the cost-price of their news. The characters discuss a number of contemporary issues, culminating in the news from the Moon — which allows for satire on a range of subjects. The Moon is described as "an earth inhabited...With navigable seas and rivers...forests, parks, coney-ground, meadow-pasture, what not?" With all the similarities between Earth and Moon, though, there are differences; the Moon's denizens have no spoken language, rather communicating by signs — which renders all the lawyers mute. They also have no tailors; as a result, the lunar "self-lovers" have all died.

text: The gravitational attraction between Earth and the Moon causes tides on Earth. The same effect on the Moon has led to its tidal locking: its rotation period is the same as the time it takes to orbit Earth. As a result, it always presents the same face to the planet. As the Moon orbits Earth, different parts of its face are illuminated by the Sun, leading to the lunar phases; the dark part of the face is separated from the light part by the solar terminator.

text: The gravitational attraction between Earth and the Moon causes

text: tide

text: s on Earth. The same effect on the Moon has led to its

text: tidal locking

text: : its rotation period is the same as the time it takes to orbit Earth. As a result, it always presents the same face to the planet. As the Moon orbits Earth, different parts of its face are illuminated by the Sun, leading to the

text: lunar phase

text: s; the dark part of the face is separated from the light part by the

text: solar terminator

text: This inclination is on average about 5° 9′, much larger than the apparent mean diameter of the Sun (32′ 2″), the Moon as seen from the surface of the Earth right beneath the Moon (31′ 37″), and the shadow of the Earth at the mean lunar distance (1° 23′).

text: This

text: inclination

text: is on average about 5° 9′, much larger than the apparent mean diameter of the Sun (32′ 2″), the Moon as seen from the surface of the Earth right beneath the Moon (31′ 37″), and the shadow of the Earth at the mean lunar distance (1° 23′).

text: Panthea and Ione interrupt the Earth and the Moon by describing the passing of the music as a nymph rising from water. Panthea then claims, "A mighty Power, which is as darkness,/ Is rising out of Earth, and from the sky/ Is showered like night, and from within the air/ Bursts, like eclipse which has been gathered up/ Into the pores of sunlight". Demogorgon appears and speaks to the Earth, the Moon, and "Ye kings of suns and stars, Dæmons and Gods,/ Ætherial Dominations, who possess/ Elysian, windless, fortunate abodes/ Beyond Heaven's constellated wilderness".The Demogorgon speaks to all of the voices the final lines of the play:

text: Nishina is the remnant of a lunar crater that is located in the southern hemisphere on the far side of the Moon. It lies to the south-southwest of the crater Maksutov, to the southeast of Finsen and Leibniz.

text: Nishina is the remnant of a

text: lunar

text: crater

text: that is located in the southern

text: hemisphere

text: on the

text: far side

text: of the

text: Moon

text: . It lies to the south-southwest of the crater

text: Maksutov

text: , to the southeast of

text: Finsen

text: and

text: Leibniz

text: There was also a region on the Lunar farside that was briefly misidentified as a mare and named Mare Desiderii (Sea of Desire). It is no longer recognized. Other former maria include:

text: There was also a region on the Lunar farside that was briefly misidentified as a mare and named

text: Mare Desiderii

text: (Sea of Desire). It is no longer recognized. Other former maria include:

text: A partial solar eclipse will occur on March 29, 2025. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on March 29, 2025. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: Indirect evidence for the giant impact scenario comes from rocks collected during the Apollo Moon landings, which show oxygen isotope ratios nearly identical to those of Earth. The highly anorthositic composition of the lunar crust, as well as the existence of KREEP-rich samples, suggest that a large portion of the Moon once was molten; and a giant impact scenario could easily have supplied the energy needed to form such a magma ocean. Several lines of evidence show that if the Moon has an iron-rich core, it must be a small one. In particular, the mean density, moment of inertia, rotational signature, and magnetic induction response of the Moon all suggest that the radius of its core is less than about 25% the radius of the Moon, in contrast to about 50% for most of the other terrestrial bodies. Appropriate impact conditions satisfying the angular momentum constraints of the Earth–Moon system yield a Moon formed mostly from the mantles of the Earth and the impactor, while the core of the impactor accretes to the Earth. It is noteworthy that the Earth has the highest density of all the planets in the Solar system ; the absorption of the core of the impactor body renders this observation explicable, given the proposed properties of the early Earth and Theia.

text: Indirect evidence for the giant impact scenario comes from rocks collected during the

text: Apollo Moon landing

text: s, which show

text: oxygen

text: isotope

text: ratios nearly identical to those of Earth. The highly

text: anorthositic

text: composition of the lunar crust, as well as the existence of

text: KREEP

text: -rich samples, suggest that a large portion of the Moon once was molten; and a giant impact scenario could easily have supplied the energy needed to form such a

text: magma ocean

text: . Several lines of evidence show that if the Moon has an

text: iron

text: -rich core, it must be a small one. In particular, the mean density, moment of inertia, rotational signature, and magnetic induction response of the Moon all suggest that the radius of its core is less than about 25% the radius of the Moon, in contrast to about 50% for most of the other

text: terrestrial

text: bodies. Appropriate impact conditions satisfying the angular momentum constraints of the Earth–Moon system yield a Moon formed mostly from the mantles of the Earth and the impactor, while the core of the impactor accretes to the Earth. It is noteworthy that the Earth has the highest density of all the planets in the Solar system ; the absorption of the core of the impactor body renders this observation explicable, given the proposed properties of the early Earth and Theia.

text: The notional tidal bulges are carried ahead of the Earth–Moon axis by the continents as a result of Earth's rotation. The eccentric mass of each bulge exerts a small amount of gravitational attraction on the Moon, with the bulge on the side of Earth closest to the Moon pulling in a direction slightly forward along the Moon's orbit (because Earth's rotation has carried the bulge forward). The bulge on the side furthest from the Moon has the opposite effect, but because the gravitational attraction varies inversely with the square of distance, the effect is stronger for the near-side bulge. As a result, some of Earth's angular (or rotational) momentum is gradually being transferred to the rotation of the Earth–Moon pair around their mutual centre of mass, called the barycentre. This slightly faster rotation causes the Earth–Moon distance to increase at approximately 38 millimetres per year. Conservation of angular momentum means that Earth's axial rotation is gradually slowing, and because of this its day lengthens by approximately 23 microseconds every year (excluding glacial rebound). Both figures are valid only for the current configuration of the continents. Tidal rhythmites from 620 million years ago show that, over hundreds of millions of years, the Moon receded at an average rate of  per year and the day lengthened at an average rate of 12 microseconds per year, both about half of their current values. See tidal acceleration for a more detailed description and references.

text: The notional tidal bulges are carried ahead of the Earth–Moon axis by the continents as a result of Earth's rotation. The eccentric mass of each bulge exerts a small amount of gravitational attraction on the Moon, with the bulge on the side of Earth closest to the Moon pulling in a direction slightly forward along the Moon's orbit (because Earth's rotation has carried the bulge forward). The bulge on the side furthest from the Moon has the opposite effect, but because the gravitational attraction varies inversely with the square of distance, the effect is stronger for the near-side bulge. As a result, some of Earth's angular (or rotational) momentum is gradually being transferred to the rotation of the Earth–Moon pair around their mutual centre of mass, called the barycentre. This slightly faster rotation causes the Earth–Moon distance to increase at approximately 38 millimetres per year.

text: Conservation of angular momentum

text: means that Earth's axial rotation is gradually slowing, and because of this its day lengthens by approximately 23 microseconds every year (excluding

text: glacial rebound

text: ). Both figures are valid only for the current configuration of the continents.

text: Tidal rhythmites

text: from 620 million years ago show that, over hundreds of millions of years, the Moon receded at an average rate of  per year and the day lengthened at an average rate of 12 microseconds per year, both about half of their current values. See

text: tidal acceleration

text: for a more detailed description and references.

text: Like all lunar maria, Oceanus Procellarum was formed by ancient basaltic flood volcanic eruptions that covered the region in a thick, nearly flat layer of solidified magma. Unlike the other lunar maria, however, Oceanus Procellarum may or may not be contained within a single well-defined impact basin. Around its edges lie many minor bays and seas, including Mare Nubium and Mare Humorum to the south. To the northeast, Oceanus Procellarum is separated from Mare Imbrium by the Carpathian Mountains. On its north-west edge lies the 32 km wide Aristarchus ray crater, which is considered as the brightest feature on the Near side of the Moon. Also, the more-prominent ray-crater Copernicus lies within the eastern edge of the mare, distinctly with its bright ray materials sprawling over the darker material. On the northern edge of Oceanus Procellarum lies Sinus Roris.

text: Like all lunar maria, Oceanus Procellarum was formed by ancient

text: basalt

text: ic flood

text: volcanic

text: eruptions that covered the region in a thick, nearly flat layer of solidified

text: magma

text: . Unlike the other lunar maria, however, Oceanus Procellarum may or may not be contained within a single well-defined impact basin. Around its edges lie many minor bays and seas, including

text: Mare Nubium

text: and

text: Mare Humorum

text: to the south. To the northeast, Oceanus Procellarum is separated from

text: Mare Imbrium

text: by the

text: Carpathian Mountains

text: . On its north-west edge lies the 32 km wide

text: Aristarchus ray crater

text: , which is considered as the brightest feature on the Near side of the Moon. Also, the more-prominent ray-crater

text: Copernicus

text: lies within the eastern edge of the mare, distinctly with its bright ray materials sprawling over the darker material. On the northern edge of Oceanus Procellarum lies

text: Sinus Roris

text: The Arkansas Apollo 17 lunar sample display commemorative style plaque, measuring 10 by 14 inches, consists of one "moon rock" particle specimen that was cut from lunar basalt 70017 and an Arkansas state flag. The basalt 70017 was collected by Apollo 17 astronaut Harrison Schmitt on the moon in 1972. Once lunar basalt 70017 was brought back to earth from the moon, the basalt moon rock was cut up into small fragments of approximately 1 gram. The piece of "moon rock" given to Arkansas weighed about 1.142-gram (0.0025 lb). The specimen was encased in a plastic ball that was mounted on the wooden plaque along with the Arkansas state flag which had been taken to the moon and back by the crew of Apollo 17. The plaque was then distributed in 1973 by President Richard Nixon to the state of Arkansas as he did that year to the other 49 states (the same as for the Apollo 11 plaque gifts). This was done as a goodwill gesture to promote peace and harmony.

text: The Arkansas Apollo 17 lunar sample display commemorative style plaque, measuring 10 by 14 inches, consists of one "moon rock" particle specimen that was cut from

text: lunar basalt 70017

text: and an Arkansas state flag. The

text: basalt

text: 70017 was collected by Apollo 17 astronaut

text: Harrison Schmitt

text: on the moon in 1972. Once lunar basalt 70017 was brought back to earth from the moon, the basalt moon rock was cut up into small fragments of approximately 1 gram. The piece of "moon rock" given to Arkansas weighed about 1.142-gram (0.0025 lb). The specimen was encased in a plastic ball that was mounted on the wooden plaque along with the Arkansas state flag which had been taken to the moon and back by the crew of Apollo 17. The plaque was then distributed in 1973 by President Richard Nixon to the state of Arkansas as he did that year to the other 49 states (the same as for the Apollo 11 plaque gifts). This was done as a goodwill gesture to promote peace and harmony.

text: A related problem is that of centrifugal forces for the Earth-Moon-Sun system, where three rotations appear: the daily rotation of the Earth about its axis, the lunar-month rotation of the Earth-Moon system about their center of mass, and the annual revolution of the Earth-Moon system about the Sun. These three motions influence the tides.

text: A related problem is that of centrifugal forces for the Earth-Moon-Sun system, where three rotations appear: the daily rotation of the Earth about its axis, the lunar-month rotation of the Earth-Moon system about their center of mass, and the annual revolution of the Earth-Moon system about the Sun. These three motions influence the

text: tides

text: Geiger is a lunar crater on the far side of the Moon. It lies to the southwest of the much larger walled plain Keeler, and slightly farther to the northeast of the huge walled plain Gagarin. To the south is the crater Cyrano.

text: Geiger is a

text: lunar

text: crater

text: on the

text: far side

text: of the

text: Moon

text: . It lies to the southwest of the much larger walled plain

text: Keeler

text: , and slightly farther to the northeast of the huge walled plain

text: Gagarin

text: . To the south is the crater

text: Cyrano

text: The strongest candidates for natural satellite habitability are currently icy satellites such as those of Jupiter and Saturn—Europa and Enceladus respectively, although if life exists in either place, it would probably be confined to subsurface habitats. Historically, life on Earth was thought to be strictly a surface phenomenon, but recent studies have shown that up to half of Earth's biomass could live below the surface. Europa and Enceladus exist outside the circumstellar habitable zone which has historically defined the limits of life within the Solar System as the zone in which water can exist as liquid at the surface. In the Solar System's habitable zone there are only three natural satellites—the Moon, and Mars's moons Phobos and Deimos (although some estimates show Mars and its moons to be slightly outside the habitable zone) —none of which sustain an atmosphere or water in liquid form. Tidal forces are likely to play as significant a role providing heat as stellar radiation in the potential habitability of natural satellites.

text: The strongest candidates for natural satellite habitability are currently icy satellites such as those of

text: Jupiter

text: and

text: Saturn

text: Europa

text: and

text: Enceladus

text: respectively, although if life exists in either place, it would probably be confined to subsurface habitats. Historically, life on Earth was thought to be strictly a surface phenomenon, but recent studies have shown that up to half of Earth's biomass could live below the surface. Europa and Enceladus exist outside the

text: circumstellar habitable zone

text: which has historically defined the limits of life within the Solar System as the zone in which water can exist as liquid at the surface. In the Solar System's habitable zone there are only three natural satellites—the

text: Moon

text: , and Mars's moons

text: Phobos

text: and

text: Deimos

text: (although some estimates show Mars and its moons to be slightly outside the habitable zone) —none of which sustain an atmosphere or water in liquid form.

text: Tidal forces

text: are likely to play as significant a role providing heat as

text: stellar radiation

text: in the potential habitability of natural satellites.

text: Humboldt is a large lunar crater that is located near the eastern limb of the Moon. Due to foreshortening this formation has an extremely oblong appearance. The actual shape of the crater is an irregular circle, with a significant indentation along the southeastern rim where the prominent crater Barnard intrudes. To the north-northwest of Humboldt is the large crater Hecataeus. Phillips is attached to the western rim.  The rim of Humboldt is low, worn, and irregular in outline.  The central peak forms a range on the crater floor. The floor surface contains a network of rilles forming a pattern of radial spokes and concentric arcs. There are also some dark patches located near the walls to the northeast, northwest, and southeast. There is a chain of craters leading from the northwest crater rim to a distance almost as long as the crater is wide. This formation is designated Catena Humboldt.  Due to its location near the lunar limb, little detail was known about this crater until it was photographed by orbiting spacecraft (mainly Lunar Orbiter 4).

text: Humboldt is a large

text: lunar

text: crater

text: that is located near the eastern limb of the

text: Moon

text: . Due to foreshortening this formation has an extremely oblong appearance. The actual shape of the crater is an irregular circle, with a significant indentation along the southeastern rim where the prominent crater

text: Barnard

text: intrudes. To the north-northwest of Humboldt is the large crater

text: Hecataeus

text: Phillips

text: is attached to the western rim.  The rim of Humboldt is low, worn, and irregular in outline.  The central peak forms a range on the crater floor. The floor surface contains a network of rilles forming a pattern of radial spokes and concentric arcs. There are also some dark patches located near the walls to the northeast, northwest, and southeast. There is a chain of craters leading from the northwest crater rim to a distance almost as long as the crater is wide. This formation is designated Catena Humboldt.  Due to its location near the lunar limb, little detail was known about this crater until it was photographed by orbiting spacecraft (mainly

text: Lunar Orbiter 4

text: A straight line connecting the pericenter and apocenter is the line of apsides. This is the major axis of the ellipse, its greatest diameter.  For a two-body system the center of mass of the system lies on this line at one of the two foci of the ellipse. When one body is sufficiently larger than the other it may be taken to be at this focus.  However whether or not this is the case, both bodies are in similar elliptical orbits each having one focus at the system's center of mass, with their respective lines of apsides being of length inversely proportional to their masses.  Historically, in geocentric systems, apsides were measured from the center of the Earth. However, in the case of the Moon, the center of mass of the Earth–Moon system, or Earth–Moon barycenter, as the common focus of both the Moon's and Earth's orbits about each other, is about 74% of the way from Earth's center to its surface.

text: A straight line connecting the pericenter and apocenter is the line of apsides. This is the major axis of the

text: ellipse

text: , its greatest diameter.  For a two-body system the

text: center of mass

text: of the system lies on this line at one of the two

text: foci

text: of the ellipse. When one body is sufficiently larger than the other it may be taken to be at this focus.  However whether or not this is the case, both bodies are in

text: similar

text: elliptical orbits each having one focus at the system's center of mass, with their respective lines of apsides being of length inversely proportional to their masses.  Historically, in

text: geocentric systems

text: , apsides were measured from the center of the Earth. However, in the case of the Moon, the center of mass of the Earth–Moon system, or

text: Earth–Moon barycenter

text: , as the common focus of both the Moon's and Earth's orbits about each other, is about 74% of the way from Earth's center to its surface.

text: The Moon's rotation and orbital periods are tidally locked with each other, so no matter when the Moon is observed from Earth the same hemisphere of the Moon is always seen. The far side of the Moon was not seen until 1959, when photographs of most of the far side were transmitted from the Soviet spacecraft Luna 3.

text: The Moon's rotation and orbital periods are tidally locked with each other, so no matter when the Moon is observed from Earth the same hemisphere of the Moon is always seen. The

text: far side of the Moon

text: was not seen until 1959, when photographs of most of the far side were transmitted from the

text: Soviet

text: spacecraft

text: Luna 3

text: White is a lunar impact crater. It lies on the far side of the Moon from the Earth, to the southwest of the huge walled plain Apollo. About one crater diameter to the south-southwest is the small  crater Hendrix.

text: White is a

text: lunar

text: impact crater

text: . It lies on the

text: far side

text: of the

text: Moon

text: from the

text: Earth

text: , to the southwest of the huge walled plain

text: Apollo

text: . About one crater diameter to the south-southwest is the small  crater

text: Hendrix

text: Brown's objective had been to produce an accurate ephemeris of the Moon, based purely on gravitational theory. For the 'main problem' of the Earth-Moon-Sun system, he calculated terms in longitude and latitude down to an uncertainty of 0.001 arcseconds. He also included perturbations due to the other planets (principally Jupiter and Venus) and also accounted for the more difficult problem of the non-spherical nature of the Earth and Moon.

text: Brown's objective had been to produce an accurate

text: ephemeris

text: of the Moon, based purely on gravitational theory. For the 'main problem' of the Earth-Moon-Sun system, he calculated terms in longitude and latitude down to an uncertainty of 0.001

text: arcseconds

text: . He also included perturbations due to the other planets (principally

text: Jupiter

text: and

text: Venus

text: ) and also accounted for the more difficult problem of the non-spherical nature of the

text: Earth

text: and Moon.

text: The great depth of this mare beneath the nearby highlands probably explains why mare units are so rare on the lunar farside. Very few basins on the farside were deep enough to allow mare volcanism. Thus, while large impact basins are found on both the nearside and farside, large maria are mostly found on the nearside. Mare lavas apparently could reach the surface more often and more easily there. The basin material is of the Nectarian epoch, while the mare material is of the Upper Imbrian epoch. Following the SELENE mission, scientists proposed that volcanism in Mare Moscoviense was active for at least ~1.5 Ga following the formation of the Moscoviense basin, but the formation of the mare as the result of a meteorite cluster impact, rather than from volcanism, has also been proposed based on the energy required to melt the lava in Mare Moscoviense.

text: The great depth of this mare beneath the nearby highlands probably explains why mare units are so rare on the lunar farside. Very few basins on the farside were deep enough to allow mare volcanism. Thus, while large impact basins are found on both the nearside and farside, large maria are mostly found on the nearside. Mare lavas apparently could reach the surface more often and more easily there. The basin material is of the

text: Nectarian

text: epoch

text: , while the mare material is of the

text: Upper Imbrian

text: epoch. Following the

text: SELENE

text: mission, scientists proposed that volcanism in Mare Moscoviense was active for at least ~1.5 Ga following the formation of the Moscoviense basin, but the formation of the mare as the result of a meteorite cluster impact, rather than from volcanism, has also been proposed based on the energy required to melt the lava in Mare Moscoviense.

text: A subject of on-going research is the formation of the Moon, some 4.53 billion years ago. A working hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, impacted Earth. In this scenario, the mass of Theia was approximately 10% of that of Earth, it impacted Earth with a glancing blow, and some of its mass merged with Earth. Between approximately 4.1 and , numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon, and by inference, to that of Earth.

text: A subject of on-going research is the formation of the Moon, some 4.53 billion years ago. A

text: working hypothesis

text: is that it was formed by accretion from material loosed from Earth after a

text: Mars

text: -sized object, named

text: Theia

text: impacted

text: Earth. In this scenario, the mass of Theia was approximately 10% of that of Earth, it impacted Earth with a glancing blow, and some of its mass merged with Earth. Between approximately 4.1 and , numerous

text: asteroid

text: impacts during the

text: Late Heavy Bombardment

text: caused significant changes to the greater surface environment of the Moon, and by inference, to that of Earth.

text: Kranz is perhaps best known for his role as lead flight director during NASA's Apollo 13 manned Moon landing mission. Kranz's team was on duty when part of the Apollo 13 Service Module exploded and they dealt with the initial hours of the unfolding accident. His "White Team", dubbed the "Tiger Team" by the press, set the constraints for the consumption of spacecraft consumables (oxygen, electricity, and water) and controlled the three course-correction burns during the trans-Earth trajectory, as well as the power-up procedures that allowed the astronauts to land safely back on Earth in the command module. He and his team, as well as the astronauts, received the Presidential Medal of Freedom for their roles.

text: Kranz is perhaps best known for his role as lead flight director during NASA's

text: Apollo 13

text: manned Moon landing mission. Kranz's team was on duty when part of the Apollo 13

text: Service Module

text: exploded and they dealt with the initial hours of the unfolding accident. His "White Team", dubbed the "Tiger Team" by the press, set the constraints for the consumption of spacecraft consumables (oxygen, electricity, and water) and controlled the three course-correction burns during the trans-Earth trajectory, as well as the power-up procedures that allowed the astronauts to land safely back on Earth in the command module. He and his team, as well as the astronauts, received the

text: Presidential Medal of Freedom

text: for their roles.

text: There are 59 known near-Earth asteroids with moons (16 Amor, 36 Apollo, and 7 Aten) with a total of 61 moons.

text: Company President/CEO Alan Stern has announced in briefing papers that the company had commenced feasibility studies into commercial missions to the Moon from early 2010 and formed the company in the third quarter of that year.  Since then, the company has been building its business models and soliciting investment.   Currently, the company has budgeted between $7 and $8 billion to achieve their objective, followed by around $1.5 billion fee per each "two-human lunar surface mission". Golden Spike will follow a model like that of the Russian spaceflight industry in the 1980s and '90s. The company said it can cut costs by partnering with other aerospace companies and using existing rockets or rockets already in development, needing to only build a lunar lander and a specialized spacesuit for astronauts for the Moon. Stern says they expect to sign up as many as 15 to 20 countries or foreign space agencies as well as companies and individuals who want to explore the Moon for science or adventure.  They have identified a mission profile, including various launch options as well as trajectory and spacecraft for landing on the Moon. It involves two sets of two launches from Earth to Earth orbit: one set for the lander and the propulsion unit to send it to Moon orbit, and the other set for the crew vehicle and the propulsion unit to send it to Moon orbit. The two propusion units are disposed of. In Moon orbit the lander and the crew vehicle have a rendez-vous, and the crew move to the lander. They land and return to the crew vehicle, and return to Earth in the crew vehicle.

text: Chalchiuitlicue's name literally means "Jade her skirt", but is usually translated as "she of the jade skirt". She was also known as Matlalcueitl "Owner of the green skirt".  This goddess was the wife (in some myths, sister) of the rain god, Tlaloc. Like other water deities, she was often associated with serpents. She was the mother of Tecciztecatl, an Aztec moon god. He was called "he who comes from the land of the sea-slug shell" because of the similarity between the moon and the slug. Tecciztecatl was portrayed as an old man who carries a large white seashell on his back.Most legends of Chalchiuhtlicue say that she was married to the god of rain, Tlaloc. In some myths she was his sister. Chalchiuhtlicue helped Tlaloc rule the kingdom of Tlalocan. It is believed that Tlaloc was one of the first 'abuser' gods and because of this Chalchiuhtlicue retaliated by releasing 52 years of rain, causing a giant flood which caused the fourth world to be destroyed. She built a bridge linking heaven and earth and those who were in Chalchiuhtlicue's good graces were allowed to traverse it. The other residents of the earth were turned into fish so they wouldn't drown. Chalchiuhtlicue used the flood as an act of purification of human kind. Because of this flood we are believed to live in the Fifth World. In some myths, Chalchiuhtlicue was wife of Xiuhtecuhtli, senior deity of the Aztec pantheon. According to Aztec legend, Chalchiuhtlicue at one point devoured the sun and moon.

text: Chalchiuitlicue's name literally means "Jade her skirt", but is usually translated as "she of the jade skirt". She was also known as Matlalcueitl "Owner of the green skirt".  This goddess was the wife (in some myths, sister) of the rain god,

text: Tlaloc

text: . Like other water deities, she was often associated with serpents. She was the mother of

text: Tecciztecatl

text: , an Aztec moon god. He was called "he who comes from the land of the sea-slug shell" because of the similarity between the moon and the slug. Tecciztecatl was portrayed as an old man who carries a large white seashell on his back.Most legends of Chalchiuhtlicue say that she was married to the god of rain, Tlaloc. In some myths she was his sister. Chalchiuhtlicue helped Tlaloc rule the kingdom of Tlalocan. It is believed that Tlaloc was one of the first 'abuser' gods and because of this Chalchiuhtlicue retaliated by releasing 52 years of rain, causing a giant flood which caused the fourth world to be destroyed. She built a bridge linking heaven and earth and those who were in Chalchiuhtlicue's good graces were allowed to traverse it. The other residents of the earth were turned into fish so they wouldn't drown. Chalchiuhtlicue used the flood as an act of purification of human kind. Because of this flood we are believed to live in the Fifth World. In some myths, Chalchiuhtlicue was wife of Xiuhtecuhtli, senior deity of the Aztec pantheon. According to Aztec legend, Chalchiuhtlicue at one point devoured the sun and moon.

text: The rocks collected from the Moon are extremely old compared to rocks found on Earth, as measured by radiometric dating techniques. They range in age from about 3.2 billion years for the basaltic samples derived from the lunar maria, to about 4.6 billion years for samples derived from the highlands crust. As such, they represent samples from a very early period in the development of the Solar System, that are largely absent on Earth. One important rock found during the Apollo Program is dubbed the Genesis Rock, retrieved by astronauts David Scott and James Irwin during the Apollo 15 mission. This anorthosite rock is composed almost exclusively of the calcium-rich feldspar mineral anorthite, and is believed to be representative of the highland crust. A geochemical component called KREEP was discovered by Apollo 12, which has no known terrestrial counterpart. KREEP and the anorthositic samples have been used to infer that the outer portion of the Moon was once completely molten (see lunar magma ocean).

text: The rocks collected from the Moon are extremely old compared to rocks found on Earth, as measured by

text: radiometric dating

text: techniques. They range in age from about 3.2 billion years for the

text: basalt

text: ic samples derived from the

text: lunar maria

text: , to about 4.6 billion years for samples derived from the

text: highlands

text: crust. As such, they represent samples from a very early period in the development of the

text: Solar System

text: , that are largely absent on Earth. One important rock found during the Apollo Program is dubbed the

text: Genesis Rock

text: , retrieved by astronauts David Scott and James Irwin during the Apollo 15 mission. This

text: anorthosite

text: rock is composed almost exclusively of the calcium-rich feldspar mineral

text: anorthite

text: , and is believed to be representative of the highland crust. A geochemical component called

text: KREEP

text: was discovered by Apollo 12, which has no known terrestrial counterpart. KREEP and the anorthositic samples have been used to infer that the outer portion of the Moon was once completely molten (see

text: lunar magma ocean

text: Lunar distance is as a unit of measure in astronomy. It is the average distance from the center of Earth to the center of the Moon. More technically, it is the mean semi-major axis of the geocentric lunar orbit. It may also refer to the time-averaged distance between the centers of the Earth and the Moon, or less commonly, the instantaneous Earth-Moon distance. The lunar distance is approximately a quarter of a million miles.

text: Lunar distance is as a

text: unit of measure

text: in

text: astronomy

text: . It is the average distance from the center of

text: Earth

text: to the center of the

text: Moon

text: . More technically, it is the mean

text: semi-major axis

text: of the geocentric lunar orbit. It may also refer to the time-averaged distance between the centers of the Earth and the Moon, or less commonly, the instantaneous Earth-Moon distance. The lunar distance is approximately a quarter of a million miles.

text: It is a narrow path for the moon to pass within the penumbra and outside the umbra. It can happen on the Earth's northern or southern penumbral edges. In addition, the size of the penumbra is sometimes too small where the moon enters it to contain the moon. The width of the Earth's penumbra is determined by the sun's angular diameter at the time of the eclipse, and the moon's angular diameter is larger than the sun over part of its elliptical orbit, depending on whether the eclipse occurs at its nearest (perigee) or farthest point (apogee) in its orbit around the earth.  The majority of the time, the size of the moon and the size of the Earth's penumbra where the moon crosses it mean that most eclipses will not be total penumbral in nature.

text: It is a narrow path for the moon to pass within the penumbra and outside the umbra. It can happen on the Earth's northern or southern penumbral edges. In addition, the size of the penumbra is sometimes too small where the moon enters it to contain the moon. The width of the Earth's penumbra is determined by the sun's

text: angular diameter

text: at the time of the eclipse, and the moon's angular diameter is larger than the sun over part of its

text: elliptical orbit

text: , depending on whether the eclipse occurs at its nearest (

text: perigee

text: ) or farthest point (apogee) in its orbit around the earth.  The majority of the time, the size of the moon and the size of the Earth's penumbra where the moon crosses it mean that most eclipses will not be total penumbral in nature.

text: Hommel is a lunar crater located in the southeast section of the Moon, in a region that is deeply impacted with a multitude of impact craters. The most notable craters nearby are Pitiscus to the north; Rosenberger due east; and Nearch to the southeast. The prominent crater Vlacq is nearly attached to the northeast rim. Also nearby is Asclepi to the west. Hommel is about 120 kilometers in diameter and its walls reach heights of 2,800 meters. It is from the Pre-Nectarian period, 4.55 to 3.92 billion years ago.

text: Hommel is a

text: lunar

text: crater

text: located in the southeast section of the

text: Moon

text: , in a region that is deeply impacted with a multitude of impact craters. The most notable craters nearby are

text: Pitiscus

text: to the north;

text: Rosenberger

text: due east; and

text: Nearch

text: to the southeast. The prominent crater

text: Vlacq

text: is nearly attached to the northeast rim. Also nearby is

text: Asclepi

text: to the west. Hommel is about 120 kilometers in diameter and its walls reach heights of 2,800 meters. It is from the Pre-

text: Nectarian

text: period, 4.55 to 3.92 billion years ago.

text: The Moon has a stabilizing effect on Earth's obliquity. Frequency map analysis conducted in 1993 suggested that, in the absence of the Moon, the obliquity can change rapidly due to orbital resonances and chaotic behavior of the Solar System, reaching as high as 90° in as little as a few million years (also see Orbit of the Moon).However, more recent numerical simulations made in 2011 indicated that even in the absence of the Moon, Earth's obliquity might not be quite so unstable; varying only by about 20–25°.The Moon's stabilizing effect will continue for less than 2 billion years. If the Moon continues to recede from Earth due to tidal acceleration, resonances may occur which will cause large oscillations of the obliquity.

text: The

text: Moon

text: has a stabilizing effect on Earth's obliquity. Frequency map analysis conducted in 1993 suggested that, in the absence of the Moon, the obliquity can change rapidly due to

text: orbital resonance

text: s and

text: chaotic behavior

text: of the Solar System, reaching as high as 90° in as little as a few million years (also see

text: Orbit of the Moon

text: ).However, more recent numerical simulations made in 2011 indicated that even in the absence of the Moon, Earth's obliquity might not be quite so unstable; varying only by about 20–25°.The Moon's stabilizing effect will continue for less than 2 billion years. If the Moon continues to recede from Earth due to

text: tidal acceleration

text: , resonances may occur which will cause large oscillations of the obliquity.

text: Weber is a lunar impact crater on the far side of the Moon, and it cannot be viewed directly from the Earth's surface. This crater is attached to the northwest outer rim of the larger crater Sarton. About two crater diameters to the northwest is the eroded Kramers.

text: Weber is a

text: lunar

text: impact crater

text: on the

text: far side

text: of the

text: Moon

text: , and it cannot be viewed directly from the

text: Earth

text: 's surface. This crater is attached to the northwest outer rim of the larger crater

text: Sarton

text: . About two crater diameters to the northwest is the eroded

text: Kramers

text: In the future, a near feudal colony has risen up around the industrialisation of the Moon, and though technology keeps the deadly natural environment at bay, the four basic essentials of life—air, water, carbon and data—come at a price. Tiny "chibs" placed in the eye to meter usage of these Four Elementals serve as a constant reminder of this. Everyone also has a "familiar": a personalized, holographic avatar that hovers over one shoulder and serves as an interface with the Moon's network, other familiars and even one's physical surroundings. The Moon is controlled by five families, dubbed the Five Dragons: the Australian Mackenzies dominate mineral extraction, the Asamoahs of Ghana control a vast underground agricultural industry, the Russian Vorontsovs run the transportation systems, the Suns of China are masters of technology and the upstart Brazilian Cortas mine helium-3 to power Earth's fusion reactors. These families, and all citizens of the Moon, operate under contracts granted by the Lunar Development Corporation (LDC), the Moon's governing body. The Mackenzies and the Cortas—the oldest and the newest lunar families, respectively—are bitter rivals, and as the novel begins, the long-simmering animosity between them seems reignited.

text: In the future, a near feudal colony has risen up around the industrialisation of the Moon, and though technology keeps the deadly natural environment at bay, the four basic essentials of life—air, water, carbon and data—come at a price. Tiny "chibs" placed in the eye to meter usage of these Four Elementals serve as a constant reminder of this. Everyone also has a "familiar": a personalized, holographic

text: avatar

text: that hovers over one shoulder and serves as an interface with the Moon's network, other familiars and even one's physical surroundings. The Moon is controlled by five families, dubbed the Five Dragons: the Australian Mackenzies dominate mineral extraction, the Asamoahs of Ghana control a vast underground agricultural industry, the Russian Vorontsovs run the transportation systems, the Suns of China are masters of technology and the upstart Brazilian Cortas mine

text: to power Earth's

text: fusion reactor

text: s. These families, and all citizens of the Moon, operate under contracts granted by the Lunar Development Corporation (LDC), the Moon's governing body. The Mackenzies and the Cortas—the oldest and the newest lunar families, respectively—are bitter rivals, and as the novel begins, the long-simmering animosity between them seems reignited.

text: Without sufficient personal hygiene, sores can develop and minor wounds may become infected. Existing health problems may be exacerbated, due to insufficient attention being paid to them by the individual. Neglect of personal hygiene may mean that the person suffers social difficulties and isolation.

text: The Moon's surface is covered in many interesting geological features. In addition to mountains, valleys, and craters, the following surface features have received names in the Lunar nomenclature. Many of these features are named after a nearby crater or mountain.

text: The

text: Moon

text: 's surface is covered in many interesting geological features. In addition to

text: mountain

text: s,

text: valley

text: s, and

text: crater

text: s, the following surface features have received names in the

text: Lunar nomenclature

text: . Many of these features are named after a nearby crater or mountain.

text: These craters appear in a continuum of diameters across the surface of the Moon, ranging in size from tiny pits to the immense South Pole–Aitken Basin with a diameter of nearly 2,500 km and a depth of 13 km. In a very general sense, the lunar history of impact cratering follows a trend of decreasing crater size with time. In particular, the largest impact basins were formed during the early periods, and these were successively overlaid by smaller craters. The size frequency distribution (SFD) of crater diameters on a given surface (that is, the number of craters as a function of diameter) approximately follows a power law with increasing number of craters with decreasing crater size. The vertical position of this curve can be used to estimate the age of the surface.

text: These craters appear in a continuum of diameters across the surface of the Moon, ranging in size from tiny pits to the immense

text: South Pole–Aitken Basin

text: with a diameter of nearly 2,500 km and a depth of 13 km. In a very general sense, the lunar history of impact cratering follows a trend of decreasing crater size with time. In particular, the largest impact basins were formed during the early periods, and these were successively overlaid by smaller craters. The

text: size frequency distribution

text: (SFD) of crater diameters on a given surface (that is, the number of craters as a function of diameter) approximately follows a

text: power law

text: with increasing number of craters with decreasing crater size. The vertical position of this curve can be used to estimate the age of the surface.

text: The Moon is Earth's largest natural satellite and the nearest major celestial object. Observing the Moon can be accomplished by using a variety of instruments ranging from the naked eye to large telescopes. For most people, the Moon is the only celestial object upon which surface features can be discerned with the naked eye.

text: The

text: Moon

text: is

text: Earth

text: 's largest

text: natural satellite

text: and the nearest major celestial object. Observing the Moon can be accomplished by using a variety of instruments ranging from the naked eye to large

text: telescope

text: s. For most people, the Moon is the only celestial object upon which surface features can be discerned with the

text: naked eye

text: Dreyer is the remnant of a lunar crater on the far side of the Moon. It is located along the eastern edge of the Mare Marginis, about midway between the craters Ginzel to the north and Erro to the south-southeast.

text: Dreyer is the remnant of a

text: lunar

text: crater

text: on the

text: far side

text: of the

text: Moon

text: . It is located along the eastern edge of the

text: Mare Marginis

text: , about midway between the craters

text: Ginzel

text: to the north and

text: Erro

text: to the south-southeast.

text: The Lunar Explorers Society is an organisation dedicated to achieving permanent presence of humanity on the Moon. The Society is open to all people in the world with an interest in Lunar exploration. It hopes to bring the best of humanity to the Moon, and to bring the benefits of the Moon to all people on Earth.

text: The Lunar Explorers Society is an organisation dedicated to achieving permanent presence of humanity on the

text: Moon

text: . The Society is open to all people in the world with an interest in

text: Lunar exploration

text: . It hopes to bring the best of humanity to the

text: Moon

text: , and to bring the benefits of the

text: Moon

text: to all people on

text: Earth

text: The Moon and Earth orbit a common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common orbit around the Sun, the period of the synodic month, from new moon to new moon, is 29.53 days. Viewed from the celestial north pole, the motion of Earth, the Moon, and their axial rotations are all counterclockwise. Viewed from a vantage point above the north poles of both the Sun and Earth, Earth orbits in a counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.44 degrees from the perpendicular to the Earth–Sun plane (the ecliptic), and the Earth–Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses.

text: The Moon and Earth orbit a common

text: barycenter

text: every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common orbit around the Sun, the period of the

text: synodic month

text: , from new moon to new moon, is 29.53 days. Viewed from the

text: celestial north pole

text: , the motion of Earth, the Moon, and their axial rotations are all

text: counterclockwise

text: . Viewed from a vantage point above the north poles of both the Sun and Earth, Earth orbits in a counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's

text: axis is tilted

text: some 23.44 degrees from the perpendicular to the Earth–Sun plane (the

text: ecliptic

text: ), and the Earth–Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between

text: lunar eclipse

text: s and

text: solar eclipse

text: s.

text: While tidal forces from the primary are common on satellites, most satellite systems remain stable.  Perturbation between satellites can occur, particularly in the early formation, as the gravity of satellites affect each other, and can result in ejection from the system or collisions between satellites or with the primary.  Simulations show that such interactions cause the orbits of the inner moons of the Uranus system to be chaotic and possibly unstable.  Some of Io's active can be explained by perturbation from Europa's gravity as their orbits resonate.Perturbation has been suggested as a reason that Neptune does not follow the 10,000:1 ratio of mass between the parent planet and collective moons as seen in all other known giant planets. One theory of the Earth-Moon system suggest that a second companion which formed at the same time as the Moon, was perturbed by the Moon early in the system's history, causing it to impact with the Moon.

text: While tidal forces from the primary are common on satellites, most satellite systems remain stable.

text: Perturbation

text: between satellites can occur, particularly in the early formation, as the gravity of satellites affect each other, and can result in ejection from the system or collisions between satellites or with the primary.  Simulations show that such interactions cause the orbits of the inner moons of the Uranus system to be chaotic and possibly unstable.  Some of Io's active can be explained by perturbation from Europa's gravity as their orbits resonate.Perturbation has been suggested as a reason that Neptune does not follow the 10,000:1 ratio of mass between the parent planet and collective moons as seen in all other known giant planets. One theory of the Earth-Moon system suggest that a second companion which formed at the same time as the Moon, was perturbed by the Moon early in the system's history, causing it to impact with the Moon.

text: The saros, a period of 6585.3211 days (14 common years + 4 leap years + 11.321 days, or 13 common years + 5 leap years + 10.321 days), is useful for predicting the times at which nearly identical eclipses will occur. Three periodicities related to lunar orbit, the synodic month, the draconic month, and the anomalistic month coincide almost perfectly each saros cycle. For an eclipse to occur, either the Moon must be located between the Earth and Sun (for a solar eclipse) or the Earth must be located between the Sun and Moon (for a lunar eclipse). This can happen only when the Moon is new or full, respectively, and repeat occurrences of these lunar phases result from solar and lunar orbits producing the Moon's synodic period of 29.53059 days. During most full and new moons, however, the shadow of the Earth or Moon falls to the north or south of the other body. Eclipses occur when the three bodies form a nearly straight line.  Because the plane of the lunar orbit is inclined to that of the earth, this condition occurs only when a full or new Moon is near or in the ecliptic plane, that is when the moon is at one of the two nodes (the ascending or descending node). The period of time for two successive lunar passes through the ecliptic plane (returning to the same node) is termed the draconic month, a 27.21222 day period.  The three-dimensional geometry of an eclipse, when the new or full moon is near one of the nodes, occurs every 5 or 6 months when the Sun is in conjunction or opposition to the Moon and coincidentally also near a node of the Moon's orbit at that time, or twice per eclipse year. Two Saros eclipses have the same appearance and duration due to the distance between the Earth and Moon being nearly the same for each event because the Saros eclipse cycle is also an integer of the anomalistic month, the period of the eccentricity of lunar orbit, 27.5545 days.

text: The saros, a period of 6585.3211 days (14 common years + 4 leap years + 11.321 days, or 13 common years + 5 leap years + 10.321 days), is useful for predicting the times at which nearly identical eclipses will occur. Three periodicities related to lunar orbit, the

text: synodic month

text: , the

text: draconic month

text: , and the

text: anomalistic month

text: coincide almost perfectly each saros cycle. For an eclipse to occur, either the Moon must be located between the Earth and Sun (for a

text: solar eclipse

text: ) or the Earth must be located between the Sun and Moon (for a

text: lunar eclipse

text: ). This can happen only when the Moon is

text: new

text: or

text: full

text: , respectively, and repeat occurrences of these

text: lunar phase

text: s result from solar and lunar orbits producing the Moon's synodic period of 29.53059 days. During most full and new moons, however, the shadow of the Earth or Moon falls to the north or south of the other body. Eclipses occur when the three bodies form a nearly straight line.  Because the plane of the lunar orbit is inclined to that of the earth, this condition occurs only when a full or new Moon is near or in the

text: ecliptic plane

text: , that is when the moon is at one of the two

text: nodes

text: (the ascending or descending node). The period of time for two successive lunar passes through the ecliptic plane (returning to the same node) is termed the draconic month, a 27.21222 day period.  The three-dimensional geometry of an eclipse, when the new or full moon is near one of the nodes, occurs every 5 or 6 months when the Sun is in conjunction or opposition to the Moon and coincidentally also near a node of the Moon's orbit at that time, or twice per

text: eclipse year

text: . Two Saros eclipses have the same appearance and duration due to the distance between the Earth and Moon being nearly the same for each event because the Saros eclipse cycle is also an integer of the anomalistic month, the period of the eccentricity of lunar orbit, 27.5545 days.

text: An eclipse involving the Sun, Earth, and Moon can occur only when they are nearly in a straight line, allowing one to be hidden behind another, viewed from the third. Because the orbital plane of the Moon is tilted with respect to the orbital plane of the Earth (the ecliptic), eclipses can occur only when the Moon is close to the intersection of these two planes (the nodes). The Sun, Earth and nodes are aligned twice a year (during an eclipse season), and eclipses can occur during a period of about two months around these times. There can be from four to seven eclipses in a calendar year, which repeat according to various eclipse cycles, such as a saros.

text: An eclipse involving the Sun, Earth, and Moon can occur only when they are nearly in a straight line, allowing one to be hidden behind another, viewed from the third. Because the

text: orbital plane of the Moon

text: is tilted with respect to the orbital plane of the Earth (the

text: ecliptic

text: ), eclipses can occur only when the Moon is close to the intersection of these two planes (the

text: node

text: s). The Sun, Earth and nodes are aligned twice a year (during an

text: eclipse season

text: ), and eclipses can occur during a period of about two months around these times. There can be from four to seven eclipses in a calendar year, which repeat according to various

text: eclipse cycle

text: s, such as a

text: saros

text: The newly formed Moon orbited at about one-tenth the distance that it does today, and spiraled outward because of tidal friction transferring angular momentum from the rotations of both bodies to the Moon's orbital motion. Along the way, the Moon's rotation became tidally locked to Earth, so that one side of the Moon continually faces toward Earth. Also, the Moon would have collided with and incorporated any small pre-existing satellites of Earth, which would have shared the Earth's composition, including isotopic abundances. The geology of the Moon has since been more independent of the Earth. Although this hypothesis explains many aspects of the Earth–Moon system, there are still a few unresolved problems, such as the Moon's volatile elements not being as depleted as expected from such an energetic impact.

text: The newly formed Moon orbited at about one-tenth the distance that it does today, and spiraled outward because of

text: tidal friction

text: transferring angular momentum from the rotations of both bodies to the Moon's orbital motion. Along the way, the Moon's rotation became

text: tidally locked

text: to Earth, so that one side of the Moon continually faces toward Earth. Also, the Moon would have collided with and incorporated any small pre-existing satellites of Earth, which would have shared the Earth's composition, including isotopic abundances. The geology of the Moon has since been more independent of the Earth. Although this hypothesis explains many aspects of the Earth–Moon system, there are still a few unresolved problems, such as the Moon's volatile

text: element

text: s not being as depleted as expected from such an energetic impact.

text: While scientific experiments performed by Clementine and Lunar Prospector could indicate the presence of water in the polar craters, the current evidence is far from definitive. There are doubts among scientists as to whether or not the hydrogen is in the form of ice, as well as to the concentration of this "ore" with depth below the surface. Resolution of this issue will require future missions to the Moon. The presence of water suggests that the crater floor could potentially be "mined" for deposits of hydrogen in water form, a commodity that is expensive to deliver directly from the Earth.

text: While scientific experiments performed by

text: Clementine

text: and

text: Lunar Prospector

text: could indicate the presence of water in the polar craters, the current evidence is far from definitive. There are doubts among scientists as to whether or not the hydrogen is in the form of ice, as well as to the concentration of this "ore" with depth below the surface. Resolution of this issue will require future missions to the Moon. The presence of water suggests that the crater floor could potentially be "mined" for deposits of

text: hydrogen

text: in water form, a commodity that is expensive to deliver directly from the Earth.

text: Craters of the Moon is a steamfield with a total of about  of heated ground. It has an average altitude of 435 m. It has – of course – craters, but it also has fumaroles (“blowholes”) and a mudpool. Vegetation around the area of the Craters of the Moon is quite uncommon.

text: Mass wasting, also known as slope movement or mass movement, is the geomorphic process by which soil, sand, regolith, and rock move downslope typically as a mass, largely under the force of gravity, but frequently affected by water and water content as in submarine environments and mudflows. Types of mass wasting include creep, slides, flows, topples, and falls, each with its own characteristic features, and taking place over timescales from seconds to years. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth, Mars, Venus, and Jupiter's moon Io.

text: Mass wasting, also known as slope movement or mass movement, is the

text: geomorphic

text: process by which

text: soil

text: sand

text: regolith

text: , and

text: rock

text: move downslope typically as a mass, largely under the force of

text: gravity

text: , but frequently affected by water and water content as in submarine environments and

text: mudflow

text: s. Types of mass wasting include

text: creep

text: , slides, flows, topples, and falls, each with its own characteristic features, and taking place over timescales from seconds to years. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on

text: Earth

text: Mars

text: Venus

text: , and Jupiter's moon

text: Io

text: The Lunar landscape exterior was constructed by Jack Poplin and his team on Soundstage #2 at KTTV and the moon backdrops were from M.G.M. The jagged mountains and rock columns were placed so as to hide the gaps in these backdrops. The moon surface itself was a four inch deep layer of sand that had been dyed different colours to give the moonscape different gradations of tone when filmed in black and white. Paintings by astronomical artist Chesley Bonestell were used as background plates for sequences of the two Moonstones moving over the lunar surface.

text: The Lunar landscape exterior was constructed by Jack Poplin and his team on Soundstage #2 at

text: KTTV

text: and the moon backdrops were from

text: M.G.M.

text: The jagged mountains and rock columns were placed so as to hide the gaps in these backdrops. The moon surface itself was a four inch deep layer of sand that had been dyed different colours to give the moonscape different gradations of tone when filmed in black and white. Paintings by astronomical artist

text: Chesley Bonestell

text: were used as background plates for sequences of the two Moonstones moving over the lunar surface.

text: The slathem are fish-like humanoids who exist equally well both in and out of the water. The slathem have not been too terribly affected by the lunar rain. Certain of their towns and cities are underwater for part of the year, because of the immense seasonal tides characteristic of Highpoint.  The winter/summer seasons result in more polar ice cap melting/freezing than on earth, so the Highpoint seasons are labeled Highwater and Lowwater.  Increased tidal effects due to the moon only amplify this problem.

text: Libration is manifested as a slow rocking back and forth of the Moon as viewed from Earth, permitting an observer to see slightly different halves of the surface at different times.

text: The Principia deals primarily with massive bodies in motion, initially under a variety of conditions and hypothetical laws of force in both non-resisting and resisting media, thus offering criteria to decide, by observations, which laws of force are operating in phenomena that may be observed. It attempts to cover hypothetical or possible motions both of celestial bodies and of terrestrial projectiles. It explores difficult problems of motions perturbed by multiple attractive forces. Its third and final book deals with the interpretation of observations about the movements of planets and their satellites. It shows how astronomical observations prove the inverse square law of gravitation (to an accuracy that was high by the standards of Newton's time); offers estimates of relative masses for the known giant planets and for the Earth and the Sun; defines the very slow motion of the Sun relative to the solar-system barycenter; shows how the theory of gravity can account for irregularities in the motion of the Moon; identifies the oblateness of the figure of the Earth; accounts approximately for marine tides including phenomena of spring and neap tides by the perturbing (and varying) gravitational attractions of the Sun and Moon on the Earth's waters; explains the precession of the equinoxes as an effect of the gravitational attraction of the Moon on the Earth's equatorial bulge; and gives theoretical basis for numerous phenomena about comets and their elongated, near-parabolic orbits.

text: On December 24, 1968, the crew of Apollo 8, Frank Borman, James Lovell and William Anders, became the first human beings to enter lunar orbit and see the far side of the Moon in person. Humans first landed on the Moon on July 20, 1969. The first human to walk on the lunar surface was Neil Armstrong, commander of the U.S. mission Apollo 11. The first robot lunar rover to land on the Moon was the Soviet vessel Lunokhod 1 on November 17, 1970 as part of the Lunokhod program. To date, the last human to stand on the Moon was Eugene Cernan, who as part of the mission Apollo 17, walked on the Moon in December 1972. See also: A full list of lunar Apollo astronauts.

text: On December 24, 1968, the crew of

text: Apollo 8

text: Frank Borman

text: James Lovell

text: and

text: William Anders

text: , became the first human beings to enter lunar orbit and see the far side of the Moon in person. Humans first landed on the Moon on July 20, 1969. The first human to walk on the lunar surface was

text: Neil Armstrong

text: , commander of the U.S. mission

text: Apollo 11

text: . The first robot

text: lunar rover

text: to land on the Moon was the Soviet vessel

text: Lunokhod 1

text: on November 17, 1970 as part of the

text: Lunokhod program

text: . To date, the last human to stand on the Moon was

text: Eugene Cernan

text: , who as part of the mission

text: Apollo 17

text: , walked on the Moon in December 1972. See also:

text: A full list of lunar Apollo astronauts

text: Grimefighters is a British television series on ITV which follows the life of people with particularly dirty jobs: including working in a sewer, being a binman and hygiene inspectors.

text: Grimefighters is a

text: British

text: television series on

text: ITV

text: which follows the life of

text: people

text: with particularly dirty

text: jobs

text: : including working in a

text: sewer

text: , being a

text: binman

text: and hygiene inspectors.

text: Selenographic coordinatesare used to refer to locations on the surface of Earth's moon. Any position on the lunar surface can be referenced by specifying two numerical values, which are comparable to the latitude and longitude of Earth. The longitude gives the position east or west of the Moon's prime meridian, which is the line  passing from the lunar north pole through the point on the lunar surface directly facing Earth to the lunar south pole.  (See also Earth's prime meridian.)  This can be thought of as the midpoint of the visible Moon as seen from the Earth. The latitude gives the position north or south of the lunar equator. Both of these coordinates are given in degrees.

text: Selenographic coordinatesare used to refer to locations on the surface of

text: Earth

text: 's

text: moon

text: . Any position on the lunar surface can be referenced by specifying two numerical values, which are comparable to the

text: latitude

text: and

text: longitude

text: of Earth. The longitude gives the position east or west of the Moon's prime meridian, which is the line  passing from the

text: lunar north pole

text: through the point on the lunar surface directly facing Earth to the

text: lunar south pole

text: .  (See also

text: Earth's prime meridian

text: .)  This can be thought of as the midpoint of the visible Moon as seen from the Earth. The latitude gives the position north or south of the lunar

text: equator

text: . Both of these coordinates are given in

text: degrees

text: There are two reasons why the north pole and south pole of the Moon might be attractive locations for a human colony. First, there is evidence that water may be present in some continuously shaded areas near the poles. Second, the Moon's axis of rotation is sufficiently close to being perpendicular to the ecliptic plane that the radius of the Moon's polar circles is less than 50 km. Power collection stations could therefore be plausibly located so that at least one is exposed to sunlight at all times, thus making it possible to power polar colonies almost exclusively with solar energy. Solar power would be unavailable only during a lunar eclipse, but these events are relatively brief and absolutely predictable. Any such colony would therefore require a reserve energy supply that could temporarily sustain a colony during lunar eclipses or in the event of any incident or malfunction affecting solar power collection. Hydrogen fuel cells would be ideal for this purpose, since the hydrogen needed could be sourced locally using the Moon's polar water and surplus solar power. Moreover, due to the Moon's uneven surface some sites have nearly continuous sunlight. For example, Malapert mountain, located near the Shackleton crater at the Lunar south pole, offers several advantages as a site:

text: There are two reasons why the

text: north pole

text: and

text: south pole

text: of the Moon might be attractive locations for a human colony. First, there is evidence that water may be present in some continuously shaded areas near the poles. Second, the Moon's

text: axis of rotation

text: is sufficiently close to being perpendicular to the

text: ecliptic plane

text: that the radius of the Moon's

text: polar circle

text: s is less than 50 km. Power collection stations could therefore be plausibly located so that at least one is exposed to sunlight at all times, thus making it possible to power polar colonies almost exclusively with solar energy. Solar power would be unavailable only during a

text: lunar eclipse

text: , but these events are relatively brief and absolutely predictable. Any such colony would therefore require a reserve energy supply that could temporarily sustain a colony during lunar eclipses or in the event of any incident or malfunction affecting solar power collection. Hydrogen

text: fuel cells

text: would be ideal for this purpose, since the hydrogen needed could be sourced locally using the Moon's polar water and surplus solar power. Moreover, due to the Moon's uneven surface some sites have nearly continuous sunlight. For example,

text: Malapert mountain

text: , located near the

text: Shackleton crater

text: at the Lunar south pole, offers several advantages as a site:

text: Partial melting within the mantle of the Moon gave rise to the eruption of mare basalts on the lunar surface. Analyses of these basalts indicate that the mantle is composed predominantly of the minerals olivine, orthopyroxene and clinopyroxene, and that the lunar mantle is more iron rich than that of the Earth. Some lunar basalts contain high abundances of titanium (present in the mineral ilmenite), suggesting that the mantle is highly heterogeneous in composition. Moonquakes have been found to occur deep within the mantle of the Moon about 1,000 km below the surface. These occur with monthly periodicities and are related to tidal stresses caused by the eccentric orbit of the Moon about the Earth. A few shallow moonquakes with hypocenters located about 100 km below the surface have also been detected, but these occur more infrequently and appear to be unrelated to the lunar tides.

text: Partial melting within the mantle of the Moon gave rise to the eruption of mare basalts on the lunar surface. Analyses of these basalts indicate that the mantle is composed predominantly of the minerals

text: olivine

text: orthopyroxene

text: and

text: clinopyroxene

text: , and that the lunar mantle is more iron rich than that of the Earth. Some lunar basalts contain high abundances of titanium (present in the mineral

text: ilmenite

text: ), suggesting that the mantle is highly heterogeneous in composition.

text: Moonquake

text: s have been found to occur deep within the mantle of the Moon about 1,000 km below the surface. These occur with monthly periodicities and are related to tidal stresses caused by the eccentric orbit of the Moon about the Earth. A few shallow moonquakes with hypocenters located about 100 km below the surface have also been detected, but these occur more infrequently and appear to be unrelated to the lunar tides.

text: Dubyago is a lunar crater that lies in the eastern limb of the Moon, and it appears significantly foreshortened when viewed from the Earth. It lies along the southern shore of the Mare Undarum, to the southeast of the crater Firmicus.

text: Dubyago is a

text: lunar

text: crater

text: that lies in the eastern limb of the

text: Moon

text: , and it appears significantly foreshortened when viewed from the

text: Earth

text: . It lies along the southern shore of the

text: Mare Undarum

text: , to the southeast of the crater

text: Firmicus

text: Curtius is a lunar impact crater that is located in the southern part of the Moon. From the Earth the crater appears foreshortened, making it more difficult to observe detail. Nevertheless, this is a large crater that can be readily found in even small telescopes. Curtius is located within one crater diameter of the still-larger Moretus to the southwest. To the northeast is the smaller Pentland. Curtius is 95 kilometers in diameter and 6.8 kilometers deep. It is from the Nectarian period, 3.92 to 3.85 billion years ago.

text: Curtius is a

text: lunar

text: impact crater

text: that is located in the southern part of the

text: Moon

text: . From the

text: Earth

text: the crater appears foreshortened, making it more difficult to observe detail. Nevertheless, this is a large crater that can be readily found in even small telescopes. Curtius is located within one crater diameter of the still-larger

text: Moretus

text: to the southwest. To the northeast is the smaller

text: Pentland

text: . Curtius is 95 kilometers in diameter and 6.8 kilometers deep. It is from the

text: Nectarian

text: period, 3.92 to 3.85 billion years ago.

text: The idea that the Moon was not perfectly smooth can be traced as far back as approximately 450 BC, when Democritus believed that there were "lofty mountains and hollow valleys" on the Moon. However, it was not until the end of the 15th century when serious study of selenography began. Around 1603, William Gilbert compiled the first lunar drawing based on naked-eye observations. Others soon followed, and when the telescope made its appearance, drawings were begun that at first were not very accurate, but soon became better as optics improved. In the early 18th century, the librations of the Moon were measured, showing that more than 50 percent of the lunar surface was visible to observers. In 1750, Johann Meyer produced the first reliable set of lunar coordinates that would enable astronomers to locate features on the Moon.

text: The idea that the Moon was not perfectly smooth can be traced as far back as approximately 450 BC, when

text: Democritus

text: believed that there were "lofty mountains and hollow valleys" on the Moon. However, it was not until the end of the 15th century when serious study of selenography began. Around 1603,

text: William Gilbert

text: compiled the first lunar drawing based on naked-eye observations. Others soon followed, and when the

text: telescope

text: made its appearance, drawings were begun that at first were not very accurate, but soon became better as

text: optics

text: improved. In the early 18th century, the

text: libration

text: s of the Moon were measured, showing that more than 50 percent of the lunar surface was visible to observers. In 1750,

text: Johann Meyer

text: produced the first reliable set of lunar

text: coordinates

text: that would enable astronomers to locate features on the Moon.

text: The Moon's orbit around the Earth is inclined at an angle of just over 5 degrees to the plane of the Earth's orbit around the Sun (the ecliptic). Because of this, at the time of a new moon, the Moon will usually pass to the north or south of the Sun. A solar eclipse can occur only when new moon occurs close to one of the points (known as nodes) where the Moon's orbit crosses the ecliptic.

text: The

text: Moon's orbit

text: around the Earth is inclined at an angle of just over 5 degrees to the plane of the Earth's orbit around the Sun (the

text: ecliptic

text: ). Because of this, at the time of a new moon, the Moon will usually pass to the north or south of the Sun. A solar eclipse can occur only when new moon occurs close to one of the points (known as

text: node

text: s) where the Moon's orbit crosses the ecliptic.

text: Rosenberger is an old lunar impact crater in the southeastern part of the Moon. Due to foreshortening, this crater appears oval when viewed from the Earth. From orbit, however, the crater rim is nearly circular.

text: Rosenberger is an old

text: lunar

text: impact crater

text: in the southeastern part of the

text: Moon

text: . Due to foreshortening, this crater appears oval when viewed from the

text: Earth

text: . From

text: orbit

text: , however, the crater rim is nearly circular.

text: The Moon Theater was a Moorish-style building designed by Harry Lawrie of the Omaha architectural firm of Mendelssohn, Fisher and Lawrie.   The brick and steel structure boasted an exterior finish of terra cotta, white tile and marble.  Over the entrance canopy hung a sign thirty-feet in height with the image of a crescent moon.  The interior included decorative painted panels depicting scenes of historic interest and locations within the U.S. National Parks.  Playing off the theater's name, the theater's marquee prior to its opening announced, "Moon Rises Next Sat Eve, Sessue Hayakawa in Gray Horizons".

text: The Moon Theater was a

text: Moorish-style

text: building designed by Harry Lawrie of the Omaha architectural firm of

text: Mendelssohn, Fisher and Lawrie

text: .   The brick and steel structure boasted an exterior finish of

text: terra cotta

text: , white

text: tile

text: and

text: marble

text: .  Over the entrance canopy hung a sign thirty-feet in height with the image of a

text: crescent moon

text: .  The interior included decorative painted panels depicting scenes of historic interest and locations within the

entity_name: List of national parks of the United States

text: U.S. National Parks

text: .  Playing off the theater's name, the theater's marquee prior to its opening announced, "Moon Rises Next Sat Eve,

text: Sessue Hayakawa

text: in Gray Horizons".

text: Regnault is a lunar impact crater that is located close to the northwest limb of the Moon. It lies across the western rim of the walled plain Volta, with the slightly smaller crater Stokes attached to the southern outer rim. Due to its location, Regnault is not favorably placed for viewing from the Earth. It is seen at a very oblique angle, limiting the detail that can be viewed. The visibility of this crater is also affected by libration of the Moon.

text: Regnault is a

text: lunar

text: impact crater

text: that is located close to the northwest limb of the

text: Moon

text: . It lies across the western rim of the walled plain

text: Volta

text: , with the slightly smaller crater

text: Stokes

text: attached to the southern outer rim. Due to its location, Regnault is not favorably placed for viewing from the

text: Earth

text: . It is seen at a very oblique angle, limiting the detail that can be viewed. The visibility of this crater is also affected by

text: libration

text: of the Moon.

text: The planning of infrastructure for water supply and sanitation was separated between two organizations, GOPW and GOSSD. As a result, some towns or neighborhoods received access to piped water supply, but not to sewers, which led to a deterioration of the hygiene situation.

text: The eccentricity of their orbits causes regular flexing of the three moons' shapes, with Jupiter's gravity stretching them out as they approach it and allowing them to spring back to more spherical shapes as they swing away. This tidal flexing heats the moons' interiors by friction. This is seen most dramatically in the extraordinary volcanic activity of innermost Io (which is subject to the strongest tidal forces), and to a lesser degree in the geological youth of Europa's surface (indicating recent resurfacing of the moon's exterior).

text: The

text: eccentricity

text: of their orbits causes regular flexing of the three moons' shapes, with Jupiter's gravity stretching them out as they approach it and allowing them to spring back to more spherical shapes as they swing away. This tidal flexing

text: heats

text: the moons' interiors by

text: friction

text: . This is seen most dramatically in the extraordinary

text: volcanic activity

text: of innermost Io (which is subject to the strongest tidal forces), and to a lesser degree in the geological youth of

text: Europa's surface

text: (indicating recent resurfacing of the moon's exterior).

text: Tsu Chung-Chi is a relatively small lunar impact crater on the Moon's far side. It lies to the west-southwest of the crater Leonov, and to the northeast of the large walled plain Mendeleev. To the north of Tsu Chung-Chi is the Mare Moscoviense, one of the few maria on the Moon's far side.

text: Tsu Chung-Chi is a relatively small

text: lunar

text: impact crater

text: on the

text: Moon

text: 's

text: far side

text: . It lies to the west-southwest of the crater

text: Leonov

text: , and to the northeast of the large walled plain

text: Mendeleev

text: . To the north of Tsu Chung-Chi is the

text: Mare Moscoviense

text: , one of the few

text: maria

text: on the Moon's far side.

text: A partial lunar eclipse occurs when only a portion of the moon enters the umbra. When the moon travels completely into the Earth's umbra, one observes a total lunar eclipse. The moon's speed through the shadow is about one kilometer per second (2,300 mph), and totality may last up to nearly 107 minutes. Nevertheless, the total time between the moon's first and last contact with the shadow is much longer and could last up to four hours. The relative distance of the moon from the Earth at the time of an eclipse can affect the eclipse's duration. In particular, when the moon is near its apogee, the farthest point from the Earth in its orbit, its orbital speed is the slowest. The diameter of the umbra does not decrease appreciably within the changes in the orbital distance of the moon. Thus, a totally eclipsed moon occurring near apogee will lengthen the duration of totality.

text: A partial lunar eclipse occurs when only a portion of the moon enters the umbra. When the moon travels completely into the Earth's umbra, one observes a total lunar eclipse. The moon's speed through the shadow is about one kilometer per second (2,300 mph), and totality may last up to nearly 107 minutes. Nevertheless, the total time between the moon's first and last contact with the shadow is much longer and could last up to four hours. The relative distance of the moon from the Earth at the time of an eclipse can affect the eclipse's duration. In particular, when the moon is near its

text: apogee

text: , the farthest point from the Earth in its orbit, its orbital speed is the slowest. The diameter of the umbra does not decrease appreciably within the changes in the orbital distance of the moon. Thus, a totally eclipsed moon occurring near apogee will lengthen the duration of totality.

text: Single words would be translated into phrases. For example, "moon" would be played as "the Moon looks towards earth", and "war" as "war which causes attention to ambushes".

text: Lunar orbiters have to remain properly oriented with respect to the Earth, Moon and Sun. All onboard detectors must be kept facing the lunar surface in order to complete their scientific missions, communication antennas have to face the Earth in order to receive commands and transfer scientific data, and solar panels must be oriented toward the Sun in order to acquire power. During lunar orbit, the Earth, the Moon and the Sun also move, so attitude control is a complex three-vector control process. The Chang'e satellites need to adjust their attitude very carefully to maintain an optimal angle towards all three bodies.

text: Lunar orbiters have to remain properly oriented with respect to the Earth, Moon and Sun. All onboard detectors must be kept facing the lunar surface in order to complete their scientific missions, communication antennas have to face the Earth in order to receive commands and transfer scientific data, and

text: solar panel

text: s must be oriented toward the Sun in order to acquire power. During lunar orbit, the Earth, the Moon and the Sun also move, so

text: attitude control

text: is a complex three-vector control process. The Chang'e satellites need to adjust their attitude very carefully to maintain an optimal angle towards all three bodies.

text: Mission directors Roland Luettgens and Giovanni Gravili worked closely with the team to turn the filming opportunities into precise technical notes which translated Chris's camera directions into instructions for the crew. After a brief test shoot in November 2010, conducted by NASA's Expedition 25 astronaut Doug Wheelock, European Space Agency astronaut Paolo Nespoli filmed most of the footage for the project in early January 2011. This new footage showed the Earth as Gagarin would have seen it almost exactly fifty years before. The film does include views of the moon, though. When Gagarin flew into the nightside of the Earth on 12 April 1961, there was a crescent moon and, according to his autobiography, Road to the Stars, Gagarin tried looking for the moon out of curiosity, to see what it looked like from space. Unfortunately, it was not in his field of view. The filmmakers added the moon into the scene as a tribute.

text: Mission directors Roland Luettgens and Giovanni Gravili worked closely with the team to turn the filming opportunities into precise technical notes which translated Chris's camera directions into instructions for the crew. After a brief test shoot in November 2010, conducted by NASA's

text: Expedition 25

text: astronaut

text: Doug Wheelock

text: , European Space Agency astronaut

text: Paolo Nespoli

text: filmed most of the footage for the project in early January 2011. This new footage showed the Earth as Gagarin would have seen it almost exactly fifty years before. The film does include views of the moon, though. When Gagarin flew into the nightside of the Earth on 12 April 1961, there was a crescent moon and, according to his autobiography,

text: Road to the Stars

text: , Gagarin tried looking for the moon out of curiosity, to see what it looked like from space. Unfortunately, it was not in his field of view. The filmmakers added the moon into the scene as a tribute.

text: Tidal flow occurs due to the moving mass of water with speed and direction as caused by the gravitational forces of the sun and the moon, and centrifugal and inertial forces on the Earth's waters. Due to its proximity to the earth, the moon exerts roughly twice the tide raising force of the sun. The gravitational forces of the sun and moon and the centrifugal/inertial forces caused by the rotation of the earth around the center of mass of the earth-moon system create two "bulges" in the Earth's oceans: one closest to the moon, and the other on the opposite side of the globe.(CNW Group, 2008). This kind of energy is unique and different from traditional hydropower that has been around for centuries. There is no need to build a dam. Essentially a turbine is stuck in naturally flowing water. As the water flows, it turns a turbine. That is converted to electricity.

text: Baldet is a lunar crater that is located on the southern hemisphere on the far side of the Moon. It lies in the lava-flooded region between the craters Cori to the north, Stoney to the southwest, and the worn walled plain Minkowski to the southeast.

text: Baldet is a

text: lunar

text: crater

text: that is located on the southern

text: hemisphere

text: on the

text: far side

text: of the

text: Moon

text: . It lies in the

text: lava

text: -flooded region between the craters

text: Cori

text: to the north,

text: Stoney

text: to the southwest, and the worn walled plain

text: Minkowski

text: to the southeast.

text: It has an estimated average equilibrium temperature of , very close to that of Earth. If Kepler-61b is Earth-like it is a good candidate for life, because the system is about one billion years old, however because of its radius (2.24 ), it is likely gaseous, with no solid surface. However, this does not totally destroy the chances of habitability in the Kepler-61 system. Kepler-61b may well have a substantially large enough Earth-like moon (with the proper atmospheric properties and pressure), capable of supporting surface liquid water, and potentially life. However, such moons do not form naturally, it would have to be captured.

text: In the case of an infinitesimally small elastic sphere, the effect of a tidal force is to distort the shape of the body without any change in volume. The sphere becomes an ellipsoid with two bulges, pointing towards and away from the other body. Larger objects distort into an ovoid, and are slightly compressed, which is what happens to the Earth's oceans under the action of the Moon. The Earth and Moon rotate about their common center of mass or barycenter, and their gravitational attraction provides the centripetal force necessary to maintain this motion. To an observer on the Earth, very close to this barycenter, the situation is one of the Earth as body 1 acted upon by the gravity of the Moon as body 2. All parts of the Earth are subject to the Moon's gravitational forces, causing the water in the oceans to redistribute, forming bulges on the sides near the Moon and far from the Moon.

text: In the case of an infinitesimally small elastic sphere, the effect of a tidal force is to distort the shape of the body without any change in volume. The sphere becomes an

text: ellipsoid

text: with two bulges, pointing towards and away from the other body. Larger objects distort into an

text: ovoid

text: , and are slightly compressed, which is what happens to the Earth's oceans under the action of the Moon. The Earth and Moon rotate about their common center of mass or

text: barycenter

text: , and their gravitational attraction provides the

text: centripetal force

text: necessary to maintain this motion. To an observer on the Earth, very close to this barycenter, the situation is one of the Earth as body 1 acted upon by the gravity of the Moon as body 2. All parts of the Earth are subject to the Moon's gravitational forces, causing the water in the oceans to redistribute, forming bulges on the sides near the Moon and far from the Moon.

text: The Moon-to-Earth mass ratio of 0.01230 (≈ ) is also notably close to 1 when compared to all other satellite-to-planet ratios. Consequently, some scientists view the Earth-Moon system as a double planet as well, though this is a minority view. Eris's lone satellite, Dysnomia, has a radius somewhere around 1/4 that of Eris; assuming similar densities (Dysnomia's compositional make-up may or may not differ substantially from Eris's), the mass ratio would be near , a value intermediate to the Moon/Earth and Charon/Pluto ratios.

text: The Moon-to-Earth mass ratio of 0.01230 (≈ ) is also notably close to 1 when compared to all other satellite-to-planet ratios. Consequently, some scientists view the Earth-Moon system as a double planet as well, though this is a minority view.

text: Eris

text: 's lone satellite,

text: Dysnomia

text: , has a radius somewhere around 1/4 that of

text: Eris

text: ; assuming similar densities (Dysnomia's compositional make-up may or may not differ substantially from Eris's), the mass ratio would be near , a value intermediate to the Moon/Earth and Charon/Pluto ratios.

text: A simple lunar trajectory stays in one plane, resulting in lunar flyby or orbit within a small range of inclination to the Moon's equator. This also permits a "free return", in which the spacecraft would return to the appropriate position for reentry into the Earth's atmosphere if it were not injected into lunar orbit. Relatively small velocity changes are usually required to correct for trajectory errors. Such a trajectory was used for the Apollo 8, Apollo 10, Apollo 11, and Apollo 12 manned lunar missions.

text: A simple lunar trajectory stays in one plane, resulting in lunar flyby or orbit within a small range of inclination to the Moon's equator. This also permits a "free return", in which the spacecraft would return to the appropriate position for reentry into the Earth's atmosphere if it were not injected into lunar orbit. Relatively small velocity changes are usually required to correct for trajectory errors. Such a trajectory was used for the

text: Apollo 8

text: Apollo 10

text: Apollo 11

text: , and

text: Apollo 12

text: manned lunar missions.

text: The Moon is a strategic element used in the Battle of the Line of the Earth–Minbari War in the 1998 telefilm, In the Beginning.   Sheridan refers to the "Moon–Mars run" in "A Distant Star".

text: The Moon is a strategic element used in the

text: Battle of the Line

text: of the

text: Earth–Minbari War

text: in the 1998 telefilm,

text: In the Beginning

text: .   Sheridan refers to the "Moon–Mars run" in "

text: A Distant Star

text: Paul Boven (JIVE, CAMRAS), along with radio amateurs and amateur astronomers, use the telescope for projects, one being Earth–Moon–Earth communication, also known as moonbounce, which allows for people on different parts of Earth to communicate via the Moon. In this technique, radio wave signals are aimed at the Moon by one location, bounce off the Moon's surface, and are detected by an antenna at a different location on Earth.

text: Paul Boven

text: JIVE

text: , CAMRAS), along with radio amateurs and amateur astronomers, use the telescope for projects, one being

text: Earth–Moon–Earth communication

text: , also known as moonbounce, which allows for people on different parts of Earth to communicate via the Moon. In this technique, radio wave signals are aimed at the Moon by one location, bounce off the Moon's surface, and are detected by an antenna at a different location on Earth.

text: According to Lucio Russo, Seleucus' arguments for a heliocentric theory were probably related to the phenomenon of tides. The annual cycle of tides (which was studied by Seleucus) can indeed hardly be explained in a geocentric system. Seleucus correctly theorized that tides were caused by the Moon, explaining that the interaction was mediated by the pneuma. He noted that the tides varied in time and strength in different parts of the world. According to Lucio Russo, Seleucus ascribed tides both to the Moon and to a whirling motion of the Earth, which could be interpreted as the motion of the Earth around the Earth-Moon center of mass.

text: According to

text: Lucio Russo

text: , Seleucus' arguments for a heliocentric theory were probably related to the phenomenon of

text: tide

text: s. The annual cycle of tides (which was studied by Seleucus) can indeed hardly be explained in a geocentric system. Seleucus correctly theorized that

text: tide

text: s were caused by the

text: Moon

text: , explaining that the interaction was mediated by the

text: pneuma

text: . He noted that the tides varied in time and strength in different parts of the world. According to

text: Lucio Russo

text: , Seleucus ascribed

text: tide

text: s both to the

text: Moon

text: and to a whirling motion of the

text: Earth

text: , which could be interpreted as the motion of the

text: Earth

text: around the

text: Earth

text: Moon

text: center of mass

text: There are three leading models for swirl formation. There are two characteristics of lunar swirls that any model of their formation must take into account:

text: Fleming is a large lunar crater that is located on the Moon's far side, and cannot be seen from the Earth. It lies about a crater diameter to the east-northeast of Hertz, and to the northwest of Lobachevskiy.

text: Fleming is a large

text: lunar

text: crater

text: that is located on the

text: Moon

text: 's

text: far side

text: , and cannot be seen from the

text: Earth

text: . It lies about a crater diameter to the east-northeast of

text: Hertz

text: , and to the northwest of

text: Lobachevskiy

text: There are two profound differences in the chemistry of lunar regolith and soil from terrestrial materials. The first is that the Moon is very dry.  As a result, those minerals with water as part of their structure such as clay, mica, and amphiboles are totally absent from the Moon. The second difference is that lunar regolith and crust are chemically reduced, rather than being significantly oxidized like the Earth's crust. In the case of the regolith, this is due in part to the constant bombardment of the lunar surface with protons (i.e. hydrogen (H) nuclei) from the solar wind. One consequence is that iron on the Moon is found in the metallic 0 and +2 oxidation state, whereas on Earth iron is found primarily in the +2 and +3 oxidation state.

text: There are two profound differences in the chemistry of lunar regolith and soil from terrestrial materials. The first is that the Moon is very dry.  As a result, those minerals with water as part of their structure such as

text: clay

text: mica

text: , and

text: amphiboles

text: are totally absent from the Moon. The second difference is that lunar regolith and crust are chemically

text: reduced

text: , rather than being significantly

text: oxidized

text: like the Earth's crust. In the case of the regolith, this is due in part to the constant bombardment of the lunar surface with protons (i.e. hydrogen (H) nuclei) from the solar wind. One consequence is that iron on the Moon is found in the metallic 0 and +2 oxidation state, whereas on Earth iron is found primarily in the +2 and +3 oxidation state.

text: For many years after Apollo, the binary accretion model was settled on as the best hypothesis for explaining the Moon's origins, even though it was known to be flawed. Then, at a conference in Kona, Hawaii in 1984, a compromise model was composed that accounted for all of the observed discrepancies. Originally formulated by two independent research groups in 1976, the giant impact model supposed that a massive planetary object, the size of Mars, had collided with Earth early in its history. The impact would have melted Earth's crust, and the other planet's heavy core would have sunk inward and merged with Earth's. The superheated vapour produced by the impact would have risen into orbit around the planet, coalescing into the Moon. This explained the lack of water (the vapour cloud was too hot for water to condense), the similarity in composition (since the Moon had formed from part of the Earth), the lower density (since the Moon had formed from the Earth's crust and mantle, rather than its core), and the Moon's unusual orbit (since an oblique strike would have imparted a massive amount of angular momentum to the Earth–Moon system).

text: A hypothetical planet-sized Earth trojan the size of Mars, named Theia, is thought by proponents of the giant-impact hypothesis to be the origin of the Moon. The hypothesis states that the Moon formed after Earth and Theia collided head-on, showering material from the two planets into space. This material eventually accreted around Earth and into a single orbiting body, the Moon.

text: A hypothetical

text: planet-sized

text: Earth trojan the size of

text: Mars

text: , named

text: Theia

text: , is thought by proponents of the

text: giant-impact hypothesis

text: to be the origin of the

text: Moon

text: . The hypothesis states that the Moon formed after Earth and Theia collided head-on, showering material from the two planets into space. This material eventually

text: accreted

text: around Earth and into a single orbiting body, the Moon.

text: When the Moon, as seen from Earth, is a narrow crescent, the Earth as seen from the Moon is almost fully lit by the Sun. Often, the part of the Moon that is not directly lit by the Sun is sufficiently brightly lit by light reflected from the Earth to be easily visible from Earth. This phenomenon is called "earthshine", and is sometimes picturesquely described as "the old moon in the new moon's arms" or, as pictured here, "the new moon in the old moon's arms".

text: When the Moon, as seen from Earth, is a narrow crescent, the Earth as seen from the Moon is almost fully lit by the Sun. Often, the part of the Moon that is not directly lit by the Sun is sufficiently brightly lit by light reflected from the Earth to be easily visible from Earth. This phenomenon is called "

text: earthshine

text: ", and is sometimes picturesquely described as "the old moon in the new moon's arms" or, as pictured here, "the new moon in the old moon's arms".

text: Galvani is a lunar crater that lies close to the northwestern limb of the Moon, due south of the larger walled plain Volta. It partly overlies the southeast rim of the crater Langley, which occupies half the gap between Volta and Galvani. To the northeast is the large walled plain Repsold, and to the west-southwest, on the far side of the Moon, is the crater McLaughlin.

text: Galvani is a

text: lunar

text: crater

text: that lies close to the northwestern limb of the

text: Moon

text: , due south of the larger walled plain

text: Volta

text: . It partly overlies the southeast rim of the crater

text: Langley

text: , which occupies half the gap between Volta and Galvani. To the northeast is the large walled plain

text: Repsold

text: , and to the west-southwest, on the

text: far side

text: of the Moon, is the crater

text: McLaughlin

text: The effect of long-period tides on lunar orbit is a controversial topic, some literatures conclude the long-period tides accelerate the moon and slow down the earth. However Cheng  found that dissipation of the long-period tides brakes the moon and actually accelerates the earth's rotation. To explain this, they assumed the earth's rotation depends not directly on the derivation of the forcing potential for the long period tides, so the form and period of the long-period constituents is independent of the rotation rate. For these constituents, the moon (or sun) can be thought of as orbiting a non-rotating earth in a plane with the appropriate inclination to the equator. Then the tidal "bulge" lags behind the orbiting moon thus decelerating it in its orbit (bringing it closer to the earth), and by angular momentum conservation, the earth's rotation must accelerate. But this argument is qualitative, and a quantitative resolution of the conflicting conclusions is still needed.

text: The U.S. co-launched the Lunar Reconnaissance Orbiter (LRO) and the LCROSS impactor and follow-up observation orbiter on 18 June 2009; LCROSS completed its mission by making a planned and widely observed impact in the crater Cabeus on 9 October 2009, whereas LRO is currently in operation, obtaining precise lunar altimetry and high-resolution imagery. In November 2011, the LRO passed over the Aristarchus crater, which spans  and sinks more than  deep. The crater is one of the most visible ones from Earth. "The Aristarchus plateau is one of the most geologically diverse places on the Moon: a mysterious raised flat plateau, a giant rille carved by enormous outpourings of lava, fields of explosive volcanic ash, and all surrounded by massive flood basalts", said Mark Robinson, principal investigator of the Lunar Reconnaissance Orbiter Camera at Arizona State University. NASA released photos of the crater on 25 December 2011.

text: The U.S. co-launched the

text: Lunar Reconnaissance Orbiter

text: (LRO) and the

text: LCROSS

text: impactor and follow-up observation orbiter on 18 June 2009; LCROSS completed its mission by making a planned and widely observed impact in the crater

text: Cabeus

text: on 9 October 2009, whereas LRO is currently in operation, obtaining precise lunar

text: altimetry

text: and high-resolution imagery. In November 2011, the LRO passed over the

text: Aristarchus crater

text: , which spans  and sinks more than  deep. The crater is one of the most visible ones from Earth. "The Aristarchus plateau is one of the most geologically diverse places on the Moon: a mysterious raised flat plateau, a giant rille carved by enormous outpourings of lava, fields of explosive volcanic ash, and all surrounded by massive flood basalts", said Mark Robinson, principal investigator of the Lunar Reconnaissance Orbiter Camera at

text: Arizona State University

text: . NASA released photos of the crater on 25 December 2011.

text: Alekhin is a lunar crater that is located on the southern hemisphere on the far side of the Moon. It lies to the north of the crater Zeeman, and south-southeast of Fizeau. To the west lies Crommelin, and east-southeast is Doerfel.

text: Alekhin is a

text: lunar

text: crater

text: that is located on the southern

text: hemisphere

text: on the

text: far side

text: of the

text: Moon

text: . It lies to the north of the crater

text: Zeeman

text: , and south-southeast of

text: Fizeau

text: . To the west lies

text: Crommelin

text: , and east-southeast is

text: Doerfel

text: Hale is a relatively young lunar impact crater that is located on the southern limb of the Moon. Over half the crater lies on the far side of the Moon, and from the Earth this formation is viewed from the side. Thus the crater must be viewed from orbit in order to discern much detail. The nearest crater of note is Wexler to the north. To the east on the far side is the huge walled plain Schrödinger, and to the southwest is the crater Demonax.

text: Hale is a relatively young

text: lunar

text: impact crater

text: that is located on the southern limb of the

text: Moon

text: . Over half the crater lies on the

text: far side

text: of the

text: Moon

text: , and from the

text: Earth

text: this formation is viewed from the side. Thus the crater must be viewed from

text: orbit

text: in order to discern much detail. The nearest crater of note is

text: Wexler

text: to the north. To the east on the far side is the huge walled plain

text: Schrödinger

text: , and to the southwest is the crater

text: Demonax

text: In representations of the Solar System, it is common to draw the trajectory of Earth from the point of view of the Sun, and the trajectory of the Moon from the point of view of Earth. This could give the impression that the Moon orbits Earth in such a way that sometimes it goes backwards when viewed from the Sun's perspective. Because the orbital velocity of the Moon around Earth (1 km/s) is small compared to the orbital velocity of Earth about the Sun (30 km/s), this never happens. There are no rearward loops in the Moon's solar orbit.

text: In representations of the

text: Solar System

text: , it is common to draw the trajectory of Earth from the point of view of the Sun, and the trajectory of the Moon from the point of view of Earth. This could give the impression that the Moon orbits Earth in such a way that sometimes it goes backwards when viewed from the Sun's perspective. Because the orbital velocity of the Moon around Earth (1 km/s) is small compared to the orbital velocity of Earth about the Sun (30 km/s), this never happens. There are no rearward loops in the Moon's solar orbit.

text: Tidal power is taken from the Earth's oceanic tides. Tidal forces are periodic variations in gravitational attraction exerted by celestial bodies. These forces create corresponding motions or currents in the world's oceans. Due to the strong attraction to the oceans, a bulge in the water level is created, causing a temporary increase in sea level.  When the sea level is raised, water from the middle of the ocean is forced to move toward the shorelines, creating a tide.  This occurrence takes place in an unfailing manner, due to the consistent pattern of the moon’s orbit around the earth.  The magnitude and character of this motion reflects the changing positions of the Moon and Sun relative to the Earth, the effects of Earth's rotation, and local geography of the sea floor and coastlines.

text: Tidal power is taken from the Earth's oceanic

text: tide

text: s.

text: Tidal force

text: s are periodic variations in gravitational attraction exerted by celestial bodies. These forces create corresponding motions or currents in the world's oceans. Due to the strong attraction to the oceans, a bulge in the water level is created, causing a temporary increase in sea level.  When the sea level is raised, water from the middle of the ocean is forced to move toward the shorelines, creating a tide.  This occurrence takes place in an unfailing manner, due to the consistent pattern of the moon’s orbit around the earth.  The magnitude and character of this motion reflects the changing positions of the Moon and Sun relative to the Earth, the

text: effects of Earth's rotation

text: , and local

text: geography of the sea floor and coastlines

text: Naoko Takeuchi's famous Pretty Soldier Sailor Moon, which has seen life as a manga series, two anime series, a live-action television show, three anime movies, and a series of stage musicals, blends elements of the story of Princess Kaguya and the Greek myth of Endymion. The series' titular superheroine's civilian name, Tsukino Usagi, means "Rabbit of the Moon," and she is the reincarnation of Princess Serenity of the Moon Kingdom, which flourished over a millennium ago until destroyed by evil forces. The Princess had been enamored of the Earth Prince Endymion, who himself was reborn as Chiba Mamoru, secretly the dapper superhero Tuxedo Kamen, or Tuxedo Mask. The name Endymion came from a Greek tale of a young shepherd (in some retellings a king) who was beloved of the moon goddess Selene, daughter of Zeus.

text: Naoko Takeuchi's famous

text: Pretty Soldier Sailor Moon

text: , which has seen life as a manga series, two anime series, a live-action television show, three anime movies, and a series of stage musicals, blends elements of the story of Princess Kaguya and the Greek myth of

text: Endymion

text: . The series' titular superheroine's civilian name,

text: Tsukino Usagi

text: , means "Rabbit of the Moon," and she is the reincarnation of

text: Princess Serenity

text: of the Moon Kingdom, which flourished over a millennium ago until destroyed by evil forces. The Princess had been enamored of the Earth Prince Endymion, who himself was reborn as

text: Chiba Mamoru

text: , secretly the dapper superhero

text: Tuxedo Kamen

text: , or

text: Tuxedo Mask

text: . The name Endymion came from a Greek tale of a young shepherd (in some retellings a king) who was beloved of the moon goddess

text: Selene

text: , daughter of

text: Zeus

text: The quality of the well water can be significantly increased by lining the well, sealing the well head, fitting a self-priming hand pump, constructing an apron, ensuring the area is kept clean and free from stagnant water and animals, moving sources of contamination (pit latrines, garbage pits, on-site sewer systems) and carrying out hygiene education. The well should be cleaned with 1% chlorine solution after construction and periodically every 6 months.

text: The quality of the well water can be significantly increased by lining the well, sealing the well head, fitting a self-priming hand pump, constructing an apron, ensuring the area is kept clean and free from stagnant water and animals, moving sources of contamination (

text: pit latrine

text: s, garbage pits,

text: on-site sewer systems

text: ) and carrying out hygiene education. The well should be cleaned with 1% chlorine solution after construction and periodically every 6 months.

text: Newer research suggests that the reason the side of the moon facing Earth has fewer impact craters is heat from Earth at the time when the Moon was formed. The lunar crust consists primarily of plagioclases formed when aluminium and calcium condensed and combined with silicates in the mantle. The cooler far side experienced condensation of these elements sooner and so formed a thicker crust; meteoroid impacts on the near side would sometimes penetrate the thinner crust here and release basaltic lava that created the maria, but would rarely do so on the far side.

text: Newer research suggests that the reason the side of the moon facing Earth has fewer impact craters is heat from Earth at the time when the Moon was formed. The lunar crust consists primarily of

text: plagioclase

text: s formed when

text: aluminium

text: and

text: calcium

text: condensed and combined with

text: silicate

text: s in the mantle. The cooler far side experienced condensation of these elements sooner and so formed a thicker crust; meteoroid impacts on the near side would sometimes penetrate the thinner crust here and release basaltic lava that created the maria, but would rarely do so on the far side.

text: Bales was played by Andy Milder in the HBO miniseries From the Earth to the Moon. He was also interviewed in the History Channel documentary Failure Is Not an Option and the NOVA documentary To the Moon.

text: Bales was played by

text: Andy Milder

text: in the

text: HBO

text: miniseries

text: From the Earth to the Moon

text: . He was also interviewed in the

text: History Channel

text: documentary Failure Is Not an Option and the

text: NOVA

text: documentary To the Moon.

text: Constructions like those in Newton's diagram can be repeated for many different positions of the Moon in its orbit. For each position, the result is a perturbation vector like LS1 or LS2 in the second diagram. Shown here is an often-presented form of the diagram that summarises sizes and directions of the perturbation vectors for many different positions of the Moon in its orbit. Each small arrow is a perturbation vector like LS, applicable to the Moon in the particular position around the orbit from which the arrow begins. The perturbations on the Moon when it is nearly in line along the Earth-Sun axis, i.e. near new or full moon, point outwards, away from the Earth. When the Moon-Earth line is 90° from the Earth-Sun axis they point inwards, towards the Earth, with a size that is only half the maximum size of the axial (outwards) perturbations. (Newton gave a rather good quantitative estimate for the size of the solar perturbing force: at quadrature where it adds to the Earth's attraction he put it at 1/178.725 of the mean terrestrial attraction, and twice as much as that at the new and full moons where it opposes and diminishes the Earth's attraction.)

text: Constructions like those in Newton's diagram can be repeated for many different positions of the Moon in its orbit. For each position, the result is a perturbation vector like LS1 or LS2 in the second diagram. Shown here is an often-presented form of the diagram that summarises sizes and directions of the perturbation vectors for many different positions of the Moon in its orbit. Each small arrow is a perturbation vector like LS, applicable to the Moon in the particular position around the orbit from which the arrow begins. The perturbations on the Moon when it is nearly in line along the Earth-Sun axis, i.e. near new or full moon, point outwards, away from the Earth. When the Moon-Earth line is 90° from the Earth-Sun axis they point inwards, towards the Earth, with a size that is only half the maximum size of the axial (outwards) perturbations. (Newton gave a rather good quantitative estimate for the size of the solar perturbing force: at

text: quadrature

text: where it adds to the Earth's attraction he put it at 1/178.725 of the mean terrestrial attraction, and twice as much as that at the new and full moons where it opposes and diminishes the Earth's attraction.)

text: In 1957 Hans Peterson conducted one of the first direct measurements of the fall of space dust on the Earth, estimating it to be 14,300,000 tons per year. If this were true, then the Moon would be covered to a very great depth as there are limited forms of erosion to remove this material. In 1961 Arthur C. Clarke popularized this possibility in his novel A Fall of Moondust. This was cause for some concern among the groups attempting to land on the Moon, so a series of new studies followed to better characterize the issue. This included the launch of several spacecraft designed to directly measure the micrometeorite flux (Pegasus satellite program) or directly measure the dust on the surface of the Moon (Surveyor Program). These showed that the flux was much lower than earlier estimates, around 10,000 to 20,000 tons per year, and that the surface of the Moon is relatively rocky. Most lunar samples returned during the Apollo Program have micrometeorite impacts marks, typically called "zap pits", on their upper surfaces.

text: In 1957 Hans Peterson conducted one of the first direct measurements of the fall of space dust on the

text: Earth

text: , estimating it to be 14,300,000 tons per year. If this were true, then the Moon would be covered to a very great depth as there are limited forms of erosion to remove this material. In 1961

text: Arthur C. Clarke

text: popularized this possibility in his novel

text: A Fall of Moondust

text: . This was cause for some concern among the groups attempting to land on the Moon, so a series of new studies followed to better characterize the issue. This included the launch of several spacecraft designed to directly measure the micrometeorite flux (

text: Pegasus satellite program

text: ) or directly measure the dust on the surface of the Moon (

text: Surveyor Program

text: ). These showed that the flux was much lower than earlier estimates, around 10,000 to 20,000 tons per year, and that the surface of the Moon is relatively rocky. Most lunar samples returned during the

text: Apollo Program

text: have micrometeorite impacts marks, typically called "zap pits", on their upper surfaces.

text: Bunsen is a lunar crater that lies near the northwestern limb of the Moon. It is located to the west of the Oceanus Procellarum and the crater von Braun. To the southeast is the crater Lavoisier, and to the northeast lies Gerard. Northwest of Bunsen, on the far side of the Moon, is McLaughlin. Due to its position this crater appears foreshortened when viewed from the Earth, and its visibility is affected by libration.

text: Bunsen is a

text: lunar

text: crater

text: that lies near the northwestern limb of the

text: Moon

text: . It is located to the west of the

text: Oceanus Procellarum

text: and the crater

text: von Braun

text: . To the southeast is the crater

text: Lavoisier

text: , and to the northeast lies

text: Gerard

text: . Northwest of Bunsen, on the

text: far side

text: of the Moon, is

text: McLaughlin

text: . Due to its position this crater appears foreshortened when viewed from the

text: Earth

text: , and its visibility is affected by

text: libration

text: If the moon's mass is not too low compared to the planet, it may in turn stabilize the planet's axial tilt, i.e. its obliquity against the orbit around the star. On Earth, the Moon has played an important role in stabilizing the axial tilt of the Earth, thereby reducing the impact of gravitational perturbations from the other planets and ensuring only moderate climate variations throughout the planet. On Mars, however, a planet without significant tidal effects from its relatively low-mass moons Phobos and Deimos, axial tilt can undergo extreme changes from 13° to 40° on timescales of  to .

text: If the moon's mass is not too low compared to the planet, it may in turn stabilize the planet's

text: axial tilt

text: , i.e. its obliquity against the orbit around the star. On Earth, the

text: Moon

text: has played an important role in stabilizing the axial tilt of the Earth, thereby reducing the impact of gravitational perturbations from the other planets and ensuring only moderate climate variations throughout the planet. On

text: Mars

text: , however, a planet without significant tidal effects from its relatively low-mass moons

text: Phobos

text: and

text: Deimos

text: , axial tilt can undergo extreme changes from 13° to 40° on timescales of  to .

text: As noted above, the Moon's orbit is also elliptical. The Moon's distance from the Earth can vary by about 6% from its average value. Therefore, the Moon's apparent size varies with its distance from the Earth, and it is this effect that leads to the difference between total and annular eclipses. The distance of the Earth from the Sun also varies during the year, but this is a smaller effect. On average, the Moon appears to be slightly smaller than the Sun as seen from the Earth, so the majority (about 60%) of central eclipses are annular. It is only when the Moon is closer to the Earth than average (near its perigee) that a total eclipse occurs.

text: As noted above, the Moon's orbit is also

text: elliptical

text: . The Moon's distance from the Earth can vary by about 6% from its average value. Therefore, the Moon's apparent size varies with its distance from the Earth, and it is this effect that leads to the difference between total and annular eclipses. The distance of the Earth from the Sun also varies during the year, but this is a smaller effect. On average, the Moon appears to be slightly smaller than the Sun as seen from the Earth, so the majority (about 60%) of central eclipses are annular. It is only when the Moon is closer to the Earth than average (near its

text: perigee

text: ) that a total eclipse occurs.

text: This planet may have Earth-like moons with bodies of water and possibly life. But giving the planet's high eccentricity, life on the moons may not evolve as well as those on Earth. From the surface of the moon, ones may see parent planet in the sky about half of the times with different phases just like the Moon seen from Earth, as well as other moons. If this planet has rings nearly as prominent as Saturn's, then the rings can be seen surrounding the planet, making this scenery even more amazing.

text: This planet may have

text: Earth-like moons

text: with bodies of water and possibly life. But giving the planet's high eccentricity, life on the moons may not evolve as well as those on Earth. From the surface of the moon, ones may see parent planet in the sky about half of the times with different phases just like the

text: Moon

text: seen from Earth, as well as other moons. If this planet has rings nearly as prominent as Saturn's, then the rings can be seen surrounding the planet, making this scenery even more amazing.

text: The Blue Moon is covered in life-giving water and an atmosphere so dense that enormous creatures hypothetically can take flight. The Blue Moon orbits a Water Cloud Jovian planet (a Jupiter-like planet that is cool enough to have visible rain clouds in its atmosphere) orbiting a close binary star system. The Blue Moon itself is roughly an earth mass but has an air pressure around three times that of Earth's at sea level.

text: The Blue Moon is covered in life-giving water and an

text: atmosphere

text: so dense that enormous creatures hypothetically can take flight. The Blue Moon orbits a

text: Water Cloud Jovian planet

text: (a Jupiter-like planet that is cool enough to have visible rain clouds in its atmosphere) orbiting a close binary star system. The Blue Moon itself is roughly an earth mass but has an air pressure around three times that of Earth's at sea level.

text: More than half of all primary schools in the developing countries with available data do not have adequate water facilities and nearly two thirds lack adequate sanitation. Even where facilities exist, they are often in poor condition. WASH in schools, sometimes called SWASH or WinS, significantly reduces hygiene related disease, increases student attendance and contributes to dignity and gender equality. WASH in Schools contributes to healthy, safe and secure school environments that can protect children from health hazards, abuse and exclusion. It also enables children to become agents of change for improving water, sanitation and hygiene practices in their families and communities.

text: "sky, day, god"| Tues-day (< OE Tīwes-dæġ lit. "day of Tīw")| ON tīvar "gods", Týr "Tīw" (the war god)| Iuppiter (Iovis), Old Latin Diū-piter (Diovis) "Jupiter"; diēs "day", deus, dīvus "god"| Zdeús (Di(w)ós) "Zeus"| d(i)yāúḥ (diváḥ, dyōḥ) "heaven", dēváḥ "god"| Av daēva- "demon"| (OCS dĭnĭ (dĭne) "day" < ), Russian divo "miracle"| OPrus deina "day", deiws "god", Lith diena "day", dievas "god"| OIr dīe, W dydd "day"; OIr dia (dē), OW duiu- "God"| tiv "day" Asdovadz  Astwadz "God"  | (gdhinj "I make day"(? mache Tag) < )|||-|  "sun"| sun (< OE sunne)| sauil, sunnō "sun"| sōl "sun"| Homeric hēélios "sun" < *sāwélios| súvar (súraḥ) "sun, light, heavens", sūra-, sūrya "sun"| Av hvarǝ (hūrō) "sun, light, heavens"| OCS slĭnŭce "sun" < *sulnika-, Russian po-solon' "sunwise"| OPrus sauli "sun", sawaiti "week", Lith saulė "sun", savaitė "week"| OIr sūil "eye"; W haul "sun"| Armenian, arev Sun, tsolk reflection, shoghal shine, glare; shogh շող "gleen."| ylli "star" < *sūlo- or *sūli-|||-|  "moon, month"| moon (< OE mōna), month (< OE mōnaþ)| mēna "moon", mēnoþs "month"| mēnsis "month"| Att mḗn, Ion meis, Dor mḗs "month", mḗnē "moon"| mā́s "moon"; mā́sa "month"| Av mā̊ (mā̊ŋhō) "moon"; NPers māh "moon, month"| OCS měsęcĭ "moon, month" < | OPrus miniks "moon", mins "month", Lith mėnulis "moon", mėnesis "month"| OIr mī (mīs) "month" < ;; W mis "month"| amis (amsoy) "month" < | muai "month"| A mañ B meñe "month"; A mañ ñkät B meṃ "moon"||-|  "earth"||| humus "earth"| kʰtʰṓn (kʰtʰonós) "earth", kʰamaí "on the earth"| kṣā́ḥ (acc. kṣā́m, gen. jmáḥ) "earth"| Av zā̊ (acc. ząm, gen. zǝmō) "earth"| OCS zemĭ, zemlja "earth"| OPrus zemê "earth", Lith žemė " earth"| OIr dū "place"; Welsh dyn "man"| degh "place", hogh "earth, soil, land", tsekh "mud, wet soil"| dhe "earth"| A tkaṃ (tkanis), B keṃ "earth"| tēkan (tagnās) "earth"|-|  pl.  "water"| water (< OE wæter)| watō (watins) "water"| Umbrian utur "water", Latin unda "wave"| húdōr (húdatos) "water"| udakám (loc. udán(i), pl. udá), udra "water"| Av aoδa- "spring", vaiδi- "stream"| OCS voda "water", Russian vedro "bucket", | OPrus undan "water", Lith vanduo "water"| OIr u(i)sce "water" < *udeskyo-| get "river" < *wedō, tchur water; terchel to wet| ujë "water"| A wär, B war "water"| wātar (wetenas) "water"|-|  "wood, tree"| tree (< OE trēo)| triu "tree, wood"|| dóru "spear"| dā́ru (drṓs) "wood"| Av dāru- "tree, wood"| OCS drěvo "tree"| OPrus drawê "hole in a tree, hollow tree", Lith drevė "hole in a tree", dirva "soil"| OIr daur "oak", W derwen "oak"| tram "firm",  Western Armenian dzar "tree"| dru "tree"| AB or "wood"| taru "tree"|-|  "wind",  "to blow"| wind (< OE wind); OE wāwan "to blow"| winds "wind"; waian "to blow"| ventus "wind"| áenta (acc.) "wind", áēsi "(he) blows"| vā́taḥ (vānt-) "wind", vāti "(he) blows"| Av vātō "wind", vāiti "(he) blows"| OCS vějǫ (vějetŭ) "to blow"| OPrus witra "wind", Lith vėjas "wind", vėtra "heavy wind"| W gwynt "wind"|  Armenian hov wind|| A want, B yente "wind"| ḫūwanz "wind"|-|  "to snow"| snow (< OE snāw < , snīwan "to snow" < )| snáiws "snow"| nix (nivis) "snow", ninguō (ninguere) "to snow"| nípʰa (acc.) "snow", neípʰei "it snows"| sneha- "snow"| Av snaēža- "to snow"; Shughni žǝnij "snow" < *snaiga-| OCS sněgŭ "snow"| OPrus snaigs "snow", Lith snigti "to snow"| OIr snecht(a)e, W nyf "snow"; OIr snigid "it rains"| W. Armenian, tseun or tsouyn "snow"||||-|  "bonfire"| fire (< OE fȳr < *fuïr)| fōn (funins) "fire"; OHG fuïr (two syllables) < | Umbrian pir "fire" < *pūr, acc. purom-e "into the fire" < *pur-| pũr (purós) "fire"| pāru (pēru) "sun, fire"|| Czech pýř "glowing ash"| OPrus pannu "fire"|| hur (hroy) "fire" < *pū̆r-, hn-oc̣ "furnace" < *pū̆n-|| A por, B puwar, puwār, pwār "fire"| paḫḫur "fire"|-|  "warm"| ?warm (< OE wearm); OE ġierwan "to prepare, cook" < PGerm *garwjan| ?warmjan "to warm"| formus "warm"| tʰermós "warm"| gʰarmáḥ "heat"| Av garǝma- "hot, heat"; OPers Garma-pada-, name of the fourth month, corresponding to June/July, orig. (?) "entrance of the heat"| Russian žar "heat", goret' "to warm" < | OPrus garmê "heat, glowing", Lith žarijos "cinders", žėrėti "to glow"| OIr gorn "fire" < | ǰerm "warm"| Gheg zjarm "fire, heat"| A śärme "heat (of summer)"||-|  "light, brightness"| light (< OE lēoht)| liuhaþ (liuhadis) "light"| lūceō (lūcēre) "to shine", lūx "light"| leukós "bright, shining, white"| rócate "(he) shines", roká- "light", loka- "world, place"| Av raočant- "shining", raočah "light"; OPers raučah "light"| OCS luča "ray, flash" < *loukyā| OPrus lauk "bright", lauksna "star", laukas "field", Lith laukas "outside, field"| OIr luchair "shine"; W llachar "bright", llug "shimmer"| lois (lusoi) "light"|| AB lyuk/luk- "to shine"| luk(k)- "to shine"|-|}

text: "sky, day, god"| Tues-day (<

text: OE

text: Tīwes-dæġ lit. "day of Tīw")|

text: ON

text: tīvar "gods",

text: Týr

text: "Tīw" (the war god)| Iuppiter (Iovis),

text: Old Latin

text: Diū-piter (Diovis) "Jupiter"; diēs "day", deus, dīvus "god"| Zdeús (Di(w)ós) "Zeus"| d(i)yāúḥ (diváḥ, dyōḥ) "heaven", dēváḥ "god"|

text: Av

text: daēva- "demon"| (

text: OCS

text: dĭnĭ (dĭne) "day" < ), Russian divo "miracle"|

text: OPrus

text: deina "day", deiws "god",

text: Lith

text: diena "day", dievas "god"|

text: OIr

text: dīe,

text: W

text: dydd "day";

text: OIr

text: dia (dē),

text: OW

text: duiu- "God"| tiv "day" Asdovadz  Astwadz "God"  | (gdhinj "I make day"(? mache Tag) < )|||-|  "sun"| sun (<

text: OE

text: sunne)| sauil, sunnō "sun"| sōl "sun"|

text: Homeric

text: hēélios "sun" < *sāwélios| súvar (súraḥ) "sun, light, heavens", sūra-, sūrya "sun"|

text: Av

text: hvarǝ (hūrō) "sun, light, heavens"|

text: OCS

text: slĭnŭce "sun" < *sulnika-, Russian po-solon' "sunwise"|

text: OPrus

text: sauli "sun", sawaiti "week",

text: Lith

text: saulė "sun", savaitė "week"|

text: OIr

text: sūil "eye";

text: W

text: haul "sun"| Armenian, arev Sun, tsolk reflection, shoghal shine, glare; shogh շող "gleen."| ylli "star" < *sūlo- or *sūli-|||-|  "moon, month"| moon (<

text: OE

text: mōna), month (<

text: OE

text: mōnaþ)| mēna "moon", mēnoþs "month"| mēnsis "month"|

text: Att

text: mḗn,

text: Ion

text: meis,

text: Dor

text: mḗs "month", mḗnē "moon"| mā́s "moon"; mā́sa "month"|

text: Av

text: mā̊ (mā̊ŋhō) "moon";

text: NPers

text: māh "moon, month"|

text: OCS

text: měsęcĭ "moon, month" < |

text: OPrus

text: miniks "moon", mins "month",

text: Lith

text: mėnulis "moon", mėnesis "month"|

text: OIr

text: mī (mīs) "month" < ;;

text: W

text: mis "month"| amis (amsoy) "month" < | muai "month"| A mañ B meñe "month"; A mañ ñkät B meṃ "moon"||-|  "earth"||| humus "earth"| kʰtʰṓn (kʰtʰonós) "earth", kʰamaí "on the earth"| kṣā́ḥ (acc. kṣā́m, gen. jmáḥ) "earth"|

text: Av

text: zā̊ (acc. ząm, gen. zǝmō) "earth"|

text: OCS

text: zemĭ, zemlja "earth"|

text: OPrus

text: zemê "earth",

text: Lith

text: žemė " earth"|

text: OIr

text: dū "place";

text: Welsh

text: dyn "man"| degh "place", hogh "earth, soil, land", tsekh "mud, wet soil"| dhe "earth"| A tkaṃ (tkanis), B keṃ "earth"| tēkan (tagnās) "earth"|-|  pl.  "water"| water (<

text: OE

text: wæter)| watō (watins) "water"|

text: Umbrian

text: utur "water", Latin unda "wave"| húdōr (húdatos) "water"| udakám (loc. udán(i), pl. udá), udra "water"|

text: Av

text: aoδa- "spring", vaiδi- "stream"|

text: OCS

text: voda "water", Russian vedro "bucket", |

text: OPrus

text: undan "water",

text: Lith

text: vanduo "water"|

text: OIr

text: u(i)sce "water" < *udeskyo-| get "river" < *wedō, tchur water; terchel to wet| ujë "water"| A wär, B war "water"| wātar (wetenas) "water"|-|  "wood, tree"| tree (<

text: OE

text: trēo)| triu "tree, wood"|| dóru "spear"| dā́ru (drṓs) "wood"|

text: Av

text: dāru- "tree, wood"|

text: OCS

text: drěvo "tree"|

text: OPrus

text: drawê "hole in a tree, hollow tree",

text: Lith

text: drevė "hole in a tree", dirva "soil"|

text: OIr

text: daur "oak",

text: W

text: derwen "oak"| tram "firm",  Western Armenian dzar "tree"| dru "tree"| AB or "wood"| taru "tree"|-|  "wind",  "to blow"| wind (<

text: OE

text: wind);

text: OE

text: wāwan "to blow"| winds "wind"; waian "to blow"| ventus "wind"| áenta (acc.) "wind", áēsi "(he) blows"| vā́taḥ (vānt-) "wind", vāti "(he) blows"|

text: Av

text: vātō "wind", vāiti "(he) blows"|

text: OCS

text: vějǫ (vějetŭ) "to blow"|

text: OPrus

text: witra "wind",

text: Lith

text: vėjas "wind", vėtra "heavy wind"|

text: W

text: gwynt "wind"|  Armenian hov wind|| A want, B yente "wind"| ḫūwanz "wind"|-|  "to snow"| snow (<

text: OE

text: snāw < , snīwan "to snow" < )| snáiws "snow"| nix (nivis) "snow", ninguō (ninguere) "to snow"| nípʰa (acc.) "snow", neípʰei "it snows"| sneha- "snow"|

text: Av

text: snaēža- "to snow";

text: Shughni

text: žǝnij "snow" < *snaiga-|

text: OCS

text: sněgŭ "snow"|

text: OPrus

text: snaigs "snow",

text: Lith

text: snigti "to snow"|

text: OIr

text: snecht(a)e,

text: W

text: nyf "snow";

text: OIr

text: snigid "it rains"| W. Armenian, tseun or tsouyn "snow"||||-|  "bonfire"| fire (<

text: OE

text: fȳr < *fuïr)| fōn (funins) "fire";

text: OHG

text: fuïr (two syllables) < |

text: Umbrian

text: pir "fire" < *pūr, acc. purom-e "into the fire" < *pur-| pũr (purós) "fire"| pāru (pēru) "sun, fire"||

text: Czech

text: pýř "glowing ash"|

text: OPrus

text: pannu "fire"|| hur (hroy) "fire" < *pū̆r-, hn-oc̣ "furnace" < *pū̆n-|| A por, B puwar, puwār, pwār "fire"| paḫḫur "fire"|-|  "warm"| ?warm (<

text: OE

text: wearm);

text: OE

text: ġierwan "to prepare, cook" <

text: PGerm

text: *garwjan| ?warmjan "to warm"| formus "warm"| tʰermós "warm"| gʰarmáḥ "heat"|

text: Av

text: garǝma- "hot, heat";

text: OPers

text: Garma-pada-, name of the fourth month, corresponding to June/July, orig. (?) "entrance of the heat"| Russian žar "heat", goret' "to warm" < |

text: OPrus

text: garmê "heat, glowing",

text: Lith

text: žarijos "cinders", žėrėti "to glow"|

text: OIr

text: gorn "fire" < | ǰerm "warm"|

text: Gheg

text: zjarm "fire, heat"| A śärme "heat (of summer)"||-|  "light, brightness"| light (<

text: OE

text: lēoht)| liuhaþ (liuhadis) "light"| lūceō (lūcēre) "to shine", lūx "light"| leukós "bright, shining, white"| rócate "(he) shines", roká- "light", loka- "world, place"|

text: Av

text: raočant- "shining", raočah "light";

text: OPers

text: raučah "light"|

text: OCS

text: luča "ray, flash" < *loukyā|

text: OPrus

text: lauk "bright", lauksna "star", laukas "field",

text: Lith

text: laukas "outside, field"|

text: OIr

text: luchair "shine";

text: W

text: llachar "bright", llug "shimmer"| lois (lusoi) "light"|| AB lyuk/luk- "to shine"| luk(k)- "to shine"|-|}

text: The Moon is in synchronous rotation with Earth, always showing the same face, with its near side marked by dark volcanic maria that fill the spaces between the bright ancient crustal highlands and the prominent impact craters. It is the second-brightest regularly visible celestial object in Earth's sky, after the Sun, as measured by illuminance on Earth's surface. Its surface is actually dark, although compared to the night sky it appears very bright, with a reflectance just slightly higher than that of worn asphalt. Its prominence in the sky and its regular cycle of phases have made the Moon an important cultural influence since ancient times on language, calendars, art, mythology, and, it is often speculated, the menstrual cycles of the female of the human species.

text: The Moon is in

text: synchronous rotation

text: with Earth, always showing the same face, with its

text: near side

text: marked by dark volcanic

text: maria

text: that fill the spaces between the bright ancient crustal highlands and the prominent

text: impact crater

text: s. It is the second-brightest regularly visible

text: celestial object

text: in Earth's sky, after the Sun, as measured by

text: illuminance

text: on Earth's surface. Its surface is actually dark, although compared to the night sky it appears very bright, with a

text: reflectance

text: just slightly higher than that of worn

text: asphalt

text: . Its prominence in the sky and its regular cycle of

text: phases

text: have made the Moon an important cultural influence since ancient times on

text: language

text: calendar

text: s,

text: art

text: mythology

text: , and, it is often speculated, the menstrual cycles of the female of the human species.

text: In May 1902, Méliès made his most famous film, A Trip to the Moon. It was loosely based on Jules Verne's From the Earth to the Moon and H. G. Wells' The First Men in the Moon. In the film, Méliès stars as Professor Barbenfouillis, a character similar to the astronomer he played in The Astronomer's Dream in 1898. Professor Barbenfouillis is the President of the Astronomer's Club and proposes an expedition to the Moon. A space vehicle in the form of a large artillery shell is built in his laboratory, and he uses it to launch six men (including himself) on a voyage to the Moon. The vehicle is shot out of a large cannon into space and hits the Man in the Moon in the eye. The group explores the Moon's surface before going to sleep. As they dream, they are observed by the Moon goddess Phoebe, played by Bleuette Bernon, who causes it to snow. Later, while underground, they are attacked and captured by a group of Moon aliens, played by acrobats from the Folies Bergère. Taken before the alien king, they manage to escape and are chased back to their spaceship. Then, with the aid of a rope attached to the spaceship, the men, along with an alien, fall from the Moon back to Earth, landing in the ocean (where a superimposed fish tank creates the illusion of the deep ocean). Eventually the spaceship is towed ashore and the returning adventurers are celebrated by the townspeople. At 14 minutes, it was Méliès' longest film up to that date and cost 10,000 francs to produce.

text: In May 1902, Méliès made his most famous film,

text: A Trip to the Moon

text: . It was loosely based on

text: Jules Verne

text: 's

text: From the Earth to the Moon

text: and

text: H. G. Wells

text: The First Men in the Moon

text: . In the film, Méliès stars as Professor Barbenfouillis, a character similar to the astronomer he played in The Astronomer's Dream in 1898. Professor Barbenfouillis is the President of the Astronomer's Club and proposes an expedition to the

text: Moon

text: . A space vehicle in the form of a large artillery shell is built in his laboratory, and he uses it to launch six men (including himself) on a voyage to the Moon. The vehicle is shot out of a large cannon into space and hits the

text: Man in the Moon

text: in the eye. The group explores the Moon's surface before going to sleep. As they dream, they are observed by the Moon goddess

text: Phoebe

text: , played by

text: Bleuette Bernon

text: , who causes it to snow. Later, while underground, they are attacked and captured by a group of Moon aliens, played by acrobats from the

text: Folies Bergère

text: . Taken before the alien king, they manage to escape and are chased back to their spaceship. Then, with the aid of a rope attached to the spaceship, the men, along with an alien, fall from the Moon back to

text: Earth

text: , landing in the ocean (where a superimposed fish tank creates the illusion of the deep ocean). Eventually the spaceship is towed ashore and the returning adventurers are celebrated by the townspeople. At 14 minutes, it was Méliès' longest film up to that date and cost 10,000 francs to produce.

text: Lyot is a large lunar crater that is located along the southeastern limb of the Moon. It lies within the irregular and patchy lunar mare named Mare Australe, and to the south of the crater Hamilton. Due to its location, this formation is viewed at a low angle from the Earth, and its visibility is affected by libration.

text: Lyot is a large

text: lunar

text: crater

text: that is located along the southeastern limb of the

text: Moon

text: . It lies within the irregular and patchy

text: lunar mare

text: named

text: Mare Australe

text: , and to the south of the crater

text: Hamilton

text: . Due to its location, this formation is viewed at a low angle from the

text: Earth

text: , and its visibility is affected by

text: libration

text: Tidal forces from Earth have slowed down the Moon's rotation so that the same side is always facing the Earth, a phenomenon called tidal locking. The other face, most of which is never visible from the Earth, is therefore called the "far side of the Moon". Over time some parts of the far side can be seen due to libration. In total 59 percent of the Moon's surface is visible from Earth at one time or another. Useful observation of the parts of the far side of the Moon occasionally visible from Earth is difficult because of the low viewing angle from Earth (they cannot be observed "full on").

text: Tidal forces from

text: Earth

text: have slowed down the Moon's rotation so that the same side is always facing the Earth, a phenomenon called

text: tidal locking

text: . The other face, most of which is never visible from the Earth, is therefore called the "far side of the Moon". Over time some parts of the far side can be seen due to

text: libration

text: . In total 59 percent of the Moon's surface is visible from Earth at one time or another. Useful observation of the parts of the far side of the Moon occasionally visible from Earth is difficult because of the low viewing angle from Earth (they cannot be observed "full on").

text: As seen from the Earth, the time it takes for the Moon to return to a node, the draconic month, is less than the time it takes for the Moon to return to the same ecliptic longitude as the Sun: the synodic month. The main reason is that during the time that the Moon has completed an orbit around the Earth, the Earth (and Moon) have completed about  of their orbit around the Sun: the Moon has to make up for this in order to come again into conjunction or opposition with the Sun. Secondly, the orbital nodes of the Moon precess westward in ecliptic longitude, completing a full circle in about  18.60 years, so a draconic month is shorter than a sidereal month. In all, the difference in period between synodic and draconic month is nearly  days. Likewise, as seen from the Earth, the Sun passes both nodes as it moves along its ecliptic path. The period for the Sun to return to a node is called the eclipse or draconic year: about 346.6201 d, which is about  year shorter than a sidereal year because of the precession of the nodes.

text: As seen from the Earth, the time it takes for the Moon to return to a node, the

text: draconic month

text: , is less than the time it takes for the Moon to return to the same ecliptic longitude as the Sun: the

text: synodic month

text: . The main reason is that during the time that the Moon has completed an orbit around the Earth, the Earth (and Moon) have completed about  of their orbit around the Sun: the Moon has to make up for this in order to come again into conjunction or opposition with the Sun. Secondly, the orbital nodes of the Moon

text: precess

text: westward in ecliptic longitude, completing a full circle in about  18.60 years, so a draconic month is shorter than a

text: sidereal month

text: . In all, the difference in period between synodic and draconic month is nearly  days. Likewise, as seen from the Earth, the Sun passes both nodes as it moves along its ecliptic path. The period for the Sun to return to a node is called the

text: eclipse or draconic year

text: : about 346.6201 d, which is about  year shorter than a

text: sidereal year

text: because of the precession of the nodes.

text: Blanchard is a lunar crater that lies on the far side of the Moon, just behind the southwestern limb. It lies to the south-southwest of the crater Arrhenius, and northwest of Pilâtre. Further to the south is the rugged terrain to the north of the walled plain Hausen.

text: Blanchard is a

text: lunar

text: crater

text: that lies on the

text: far side

text: of the

text: Moon

text: , just behind the southwestern limb. It lies to the south-southwest of the crater

text: Arrhenius

text: , and northwest of

text: Pilâtre

text: . Further to the south is the rugged terrain to the north of the walled plain

text: Hausen

text: In June 1977, NASA issued a fact sheet responding to recent claims that the Apollo Moon landings had been hoaxed. The fact sheet is particularly blunt and regards the idea of faking the Moon landings to be preposterous and outlandish. NASA refers to the rocks and particles collected from the Moon as being evidence of the program's legitimacy, as they claim that these rocks could not have been formed under conditions on earth. NASA also notes that all of the operations and phases of the Apollo program were closely followed and under the scrutiny of the news media, from liftoff to splashdown. NASA responds to Bill Kaysing's book, We Never Went to the Moon, by identifying one of his claims of fraud regarding the lack of a crater left on the Moon's surface by the landing of the lunar module, and refuting it with facts about the soil and cohesive nature of the surface of the Moon.

text: Theories for the formation of the Moon must explain its late formation as well as the following facts. First, the Moon has a low density (3.3 times that of water, compared to 5.5 for the earth) and a small metallic core. Second, there is virtually no water or other volatiles on the moon. Third, the Earth and Moon have the same oxygen isotopic signature (relative abundance of the oxygen isotopes). Of the theories that have been proposed to account for these phenomena, only one is widely accepted: The giant impact hypothesis  proposes that the Moon originated after a body the size of Mars (sometimes named Theia) struck the proto-Earth a glancing blow.

text: Theories for the formation of the Moon must explain its late formation as well as the following facts. First, the Moon has a low density (3.3 times that of water, compared to 5.5 for the earth) and a small metallic core. Second, there is virtually no water or other volatiles on the moon. Third, the Earth and Moon have the same oxygen

text: isotopic signature

text: (relative abundance of the oxygen isotopes). Of the theories that have been proposed to account for these phenomena, only one is widely accepted: The giant impact hypothesis  proposes that the Moon originated after a body the size of

text: Mars

text: (sometimes named

text: Theia

text: ) struck the proto-Earth a glancing blow.

text: Gernsback is a lunar crater on the far side of the Moon. It is located in the northeastern part of the uneven Mare Australe, just behind the southeastern limb. During periods of favorable libration this feature can be brought into view of the Earth, but it is seen from the side and not much detail can be observed. It is located about a crater diameter north of the larger crater Lamb, and southwest of Parkhurst.

text: Gernsback is a

text: lunar

text: crater

text: on the

text: far side

text: of the

text: Moon

text: . It is located in the northeastern part of the uneven

text: Mare Australe

text: , just behind the southeastern limb. During periods of favorable

text: libration

text: this feature can be brought into view of the

text: Earth

text: , but it is seen from the side and not much detail can be observed. It is located about a crater diameter north of the larger crater

text: Lamb

text: , and southwest of

text: Parkhurst

text: This feature was named by Johann H. Mädler after Alexander von Humboldt, in recognition of his explorations of unknown lands. It is one of only two lunar maria that are named after people, the other being Mare Smythii (named after British astronomer William Henry Smyth), and is located along the eastern lunar limb.

text: This feature was named by

text: Johann H. Mädler

text: after Alexander von Humboldt, in recognition of his explorations of unknown lands. It is one of only two lunar maria that are named after people, the other being

text: Mare Smythii

text: (named after British astronomer

text: William Henry Smyth

text: ), and is located along the eastern lunar limb.

text: The far side of the Moon is the hemisphere of the Moon that always faces away from Earth. The far side's terrain is rugged, with a multitude of impact craters and relatively few flat lunar maria. It has one of the largest craters in the Solar System, the South Pole–Aitken basin. Although both sides of the moon experience two weeks of sunlight followed by two weeks of night, the far side is also referred to as the dark side of the Moon, originally in the sense of "unknown" rather than lack of light.

text: The far side of the Moon is the

text: hemisphere

text: of the

text: Moon

text: that always faces away from

text: Earth

text: . The far side's terrain is rugged, with a multitude of

text: impact crater

text: s and relatively few flat

text: lunar maria

text: . It has one of the

text: largest craters in the Solar System

text: , the

text: South Pole–Aitken basin

text: . Although both sides of the moon experience two weeks of sunlight followed by two weeks of night, the far side is also referred to as the dark side of the Moon, originally in the sense of "unknown" rather than lack of light.

text: The more detailed models include (among other things) the bulging at the equator for the Earth, and irregular mass concentrations (due to meteor impacts) for the Moon.  The Gravity Recovery And Climate Experiment (GRACE) mission launched in 2002 consists of two probes, nicknamed "Tom" and "Jerry", in polar orbit around the Earth measuring differences in the distance between the two probes in order to more precisely determine the gravitational field around the Earth, and to track changes that occur over time.  Similarly, the Gravity Recovery and Interior Laboratory (GRAIL) mission from 2011-2012 consisted of two probes ("Ebb" and "Flow") in polar orbit around the Moon to more precisely determine the gravitational field for future navigational purposes, and to infer information about the Moon's physical makeup.

text: The more detailed models include (among other things) the bulging at the equator for the Earth, and irregular mass concentrations (due to meteor impacts) for the Moon.  The Gravity Recovery And Climate Experiment (

text: GRACE

text: ) mission launched in 2002 consists of two probes, nicknamed "Tom" and "Jerry", in polar orbit around the Earth measuring differences in the distance between the two probes in order to more precisely determine the gravitational field around the Earth, and to track changes that occur over time.  Similarly, the Gravity Recovery and Interior Laboratory (

entity_name: Gravity Recovery and Interior Laboratory

text: GRAIL

text: ) mission from 2011-2012 consisted of two probes ("Ebb" and "Flow") in polar orbit around the Moon to more precisely determine the gravitational field for future navigational purposes, and to infer information about the Moon's physical makeup.

text: A partial solar eclipse will occur on February 27, 2036. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on February 27, 2036. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Henyey is a lunar impact crater that lies on the far side of the Moon from the Earth. It is attached at the southern end to the northern rim of the crater Dirichlet. Less than a crater diameter to the northeast is the large crater Mach, and to the northwest lies Mitra.

text: Henyey is a lunar

text: impact crater

text: that lies on the

text: far side

text: of the

text: Moon

text: from the Earth. It is attached at the southern end to the northern rim of the crater

text: Dirichlet

text: . Less than a crater diameter to the northeast is the large crater

text: Mach

text: , and to the northwest lies

text: Mitra

text: Cepheus is a lunar impact crater that is located in the northeastern part of the Moon, within one crater diameter of the larger crater Franklin to the southeast. To the north-north-east is the flooded crater Oersted. The proximity of this formation to the lunar limb means it appears oblong when viewed from the Earth due to foreshortening.

text: Cepheus is a

text: lunar

text: impact crater

text: that is located in the northeastern part of the

text: Moon

text: , within one crater diameter of the larger crater

text: Franklin

text: to the southeast. To the north-north-east is the flooded crater

text: Oersted

text: . The proximity of this formation to the lunar limb means it appears oblong when viewed from the

text: Earth

text: due to foreshortening.

text: In effect, this means that the "tropical year" on the moon is only 347 days long. This is called the draconic year or eclipse year. The "seasons" on the moon fit into this period. For about half of this draconic year, the sun is north of the lunar equator (but at most 1.543°), and for the other half it is south of the lunar equator. Obviously the effect of these seasons is very minor compared to the difference between lunar night and lunar day. At the poles, there are not days and nights of about 15 earth days, but rather the sun will be "up" for 173 days at a time. "Up" here means that the centre of the sun is above the horizon. The sunrise and sunset at the poles each take about 18 days. These polar sunrises and sunsets occur around the time of eclipses (solar or lunar). For example, at the Solar eclipse of March 9, 2016, the moon was near its descending node, and the sun was near the point in the sky where the equator of the moon crosses the ecliptic. When the sun reached that point, the centre of the sun set at the north pole and rose at the south pole.

text: In effect, this means that the "

text: tropical year

text: " on the moon is only 347 days long. This is called the

text: draconic year

text: or eclipse year. The "seasons" on the moon fit into this period. For about half of this draconic year, the sun is north of the lunar equator (but at most 1.543°), and for the other half it is south of the lunar equator. Obviously the effect of these seasons is very minor compared to the difference between lunar night and lunar day. At the poles, there are not days and nights of about 15 earth days, but rather the sun will be "up" for 173 days at a time. "Up" here means that the centre of the sun is above the horizon. The sunrise and sunset at the poles each take about 18 days. These polar sunrises and sunsets occur around the time of eclipses (solar or lunar). For example, at the

text: Solar eclipse of March 9, 2016

text: , the moon was near its descending node, and the sun was near the point in the sky where the equator of the moon crosses the ecliptic. When the sun reached that point, the centre of the sun set at the north pole and rose at the south pole.

text: Space elevator designs for Earth typically have a taper of the tether that provides a uniform stress profile rather than a uniform cross-section. Because the strength requirement of a lunar space elevator is much lower than that of an Earth space elevator, a uniform cross-section is possible for the lunar space elevator. The study done for NASA's Institute of Advanced Concepts states "Current composites have characteristic heights of a few hundred kilometers, which would require taper ratios of about 6 for Mars, 4 for the Moon, and about 6000 for the Earth. The mass of the Moon is small enough that a uniform cross-section lunar space elevator could be constructed, without any taper at all." A uniform cross-section could make it possible for a lunar space elevator to be built in a double-tether pulley configuration. This configuration would greatly simplify repairs of a space elevator compared to a tapered elevator configuration. However a pulley configuration would require a strut at the counterweight hundreds of kilometers long to separate the up-tether from the down-tether and keep them from tangling. A pulley configuration might also allow the system capacity to be gradually expanded by stitching new tether material on at the Lagrange point as the tether rotated.

text: The Lunar Reconnaissance Orbiter (LRO) is the first mission of the LPRP program. Management of LRO was assigned to Goddard Space Flight Center (GSFC) in 2004. LRO launched on an Atlas V 401 rocket from Cape Canaveral Air Force Station on June 18, 2009 at 5:32 p.m. EDT (2132 GMT). The planned lift off for 5:12 p.m. EDT (2112 GMT) was slightly delayed by 20 minutes due to thunderstorms. It will orbit the Moon for one year, gathering high resolution images of the lunar surface that will allow the creation of detailed maps. LRO's goals include finding safe landing sites for human visits to the Moon, identifying lunar resources, and studying the lunar radiation environment. The LRO will provide a 3-D map of the Moon's surface to allow astronauts to return to the Moon by 2020. On board the LRO are seven instruments, the Cosmic Ray Telescope for the Effects of Radiation (CRaTER), Diviner Lunar Radiometer Experiment (DLRE), Lyman-Alpha Mapping Project (LAMP), Lunar Exploration Neutron Detector (LEND), Lunar Orbiter Laser Altimeter (LOLA), Lunar Reconnaissance Orbiter Camera (LROC), and Miniature Radio Frequency radar (Mini-RF).

text: The

text: Lunar Reconnaissance Orbiter

text: (LRO) is the first mission of the LPRP program. Management of LRO was assigned to

text: Goddard Space Flight Center

text: (GSFC) in 2004. LRO launched on an

text: Atlas V

text: 401 rocket from

text: Cape Canaveral Air Force Station

text: on June 18, 2009 at 5:32 p.m. EDT (2132 GMT). The planned lift off for 5:12 p.m. EDT (2112 GMT) was slightly delayed by 20 minutes due to thunderstorms. It will orbit the Moon for one year, gathering high resolution images of the lunar surface that will allow the creation of detailed maps. LRO's goals include finding safe landing sites for human visits to the Moon, identifying lunar resources, and studying the lunar radiation environment. The LRO will provide a 3-D map of the Moon's surface to allow astronauts to return to the Moon by 2020. On board the LRO are seven

text: instruments

text: , the Cosmic Ray Telescope for the Effects of Radiation (CRaTER), Diviner Lunar Radiometer Experiment (DLRE), Lyman-Alpha Mapping Project (LAMP), Lunar Exploration Neutron Detector (LEND), Lunar Orbiter Laser Altimeter (LOLA), Lunar Reconnaissance Orbiter Camera (LROC), and Miniature Radio Frequency radar (Mini-RF).

text: Firmicus is a lunar crater that lies in the eastern part of the Moon's near side, so that from Earth it appears oval in shape due to foreshortening. It is, however, very nearly circular. The crater is located to the west of the Mare Undarum, and northeast of the similar-sized crater Apollonius. To the north of Firmicus are the craters van Albada and Auzout. Attached to its northwest rim is the  Lacus Perseverantiae, a miniature lunar mare.

text: Firmicus is a

text: lunar

text: crater

text: that lies in the eastern part of the

text: Moon

text: 's near side, so that from

text: Earth

text: it appears oval in shape due to foreshortening. It is, however, very nearly circular. The crater is located to the west of the

text: Mare Undarum

text: , and northeast of the similar-sized crater

text: Apollonius

text: . To the north of Firmicus are the craters

text: van Albada

text: and

text: Auzout

text: . Attached to its northwest rim is the

text: Lacus Perseverantiae

text: , a miniature

text: lunar mare

text: Scholars have theorized that Hjúki and Bil may represent lunar activity, including that they may represent the phases of the moon or may represent the craters of the moon. 19th century scholar Jacob Grimm rejects the suggestion that Hjúki and Bil represent the phases of the moon, and states that Hjúki and Bil rather represent the craters on the moon seen from the earth. Grimm says that the evidence for this "is plain from the figure itself. No change of the moon could suggest the image of two children with a pail slung over their shoulders. Moreover, to this day the Swedish people see in the spots of the moon two persons carrying a big bucket on a pole." Grimm adds that:

text: Scholars have theorized that Hjúki and Bil may represent lunar activity, including that they may represent the

text: phases of the moon

text: or may represent the

text: craters of the moon

text: . 19th century scholar

text: Jacob Grimm

text: rejects the suggestion that Hjúki and Bil represent the phases of the moon, and states that Hjúki and Bil rather represent the craters on the moon seen from the earth. Grimm says that the evidence for this "is plain from the figure itself. No change of the moon could suggest the image of two children with a pail slung over their shoulders. Moreover, to this day the Swedish people see in the spots of the moon two persons carrying a big bucket on a pole." Grimm adds that:

text: Moon rock or lunar rock is rock that is found on the Earth's moon, or lunar material collected during the course of human exploration of the Moon.

text: Moon rock or lunar rock is rock that is found on the

text: Earth's moon

text: , or lunar material collected during the course of human

text: exploration of the Moon

text: For a planet, angular momentum is distributed between the spin of the planet and its revolution in its orbit, and these are often exchanged by various mechanisms. The conservation of angular momentum in the Earth–Moon system results in the transfer of angular momentum from Earth to Moon, due to tidal torque the Moon exerts on the Earth. This in turn results in the slowing down of the rotation rate of Earth, at about 65.7 nanoseconds per day, and in gradual increase of the radius of Moon's orbit, at about 3.82 centimeters per year.

text: For a planet, angular momentum is distributed between the spin of the planet and its revolution in its orbit, and these are often exchanged by various mechanisms. The conservation of angular momentum in the

text: Earth–Moon system

text: results in the transfer of angular momentum from Earth to Moon, due to

text: tidal torque

text: the Moon exerts on the Earth. This in turn results in the slowing down of the rotation rate of Earth, at about 65.7 nanoseconds per day, and in gradual increase of the radius of Moon's orbit, at about 3.82 centimeters per year.

text: Lunar eclipses can occur only at full moon, where the Moon's orbit allows it to pass through Earth's shadow. Lunar eclipses do not occur every month because the Moon usually passes above or below Earth's shadow (which is mostly restricted to the ecliptic plane). Lunar eclipses can occur only when the full moon occurs near the two nodes of the orbit, either the ascending or descending node. This causes eclipses to only occur about every 6 months, and often 2 weeks before or after a solar eclipse at new moon at the opposite node.

text: Lunar eclipse

text: s can occur only at full moon, where the Moon's orbit allows it to pass through Earth's shadow. Lunar eclipses do not occur every month because the Moon usually passes above or below Earth's shadow (which is mostly restricted to the

text: ecliptic plane

text: ). Lunar eclipses can occur only when the full moon occurs near the two

text: nodes of the orbit

text: , either the ascending or descending node. This causes eclipses to only occur about every 6 months, and often 2 weeks before or after a

text: solar eclipse

text: at

text: new moon

text: at the opposite node.

text: The Soviet space program comprised the rocketry and space exploration programs conducted by the former Soviet Union (USSR) from the 1930s until its dissolution in 1991. Over its sixty-year history, this primarily classified military program was responsible for a number of pioneering accomplishments in space flight, including the first intercontinental ballistic missile (R-7), first satellite (Sputnik 1), first animal in Earth orbit (the dog Laika on Sputnik 2), first human in space and Earth orbit (cosmonaut Yuri Gagarin on Vostok 1), first woman in space and Earth orbit (cosmonaut Valentina Tereshkova on Vostok 6), first spacewalk (cosmonaut Alexey Leonov on Voskhod 2), first Moon impact (Luna 2), first image of the far side of the moon (Luna 3) and unmanned lunar soft landing (Luna 9), first space rover (Lunokhod 1), first sample of lunar soil automatically extracted and brought to Earth (Luna 16), and first space station (Salyut 1). Further notable records included the first interplanetary probes: Venera 1 and Mars 1 to fly by Venus and Mars, respectively, Venera 3 and Mars 2 to impact the respective planet surface, and Venera 7 and Mars 3 to make soft landings on these planets.

text: The Soviet space program comprised the

text: rocketry

text: and

text: space exploration

text: programs conducted by the former

text: Soviet Union

text: (USSR) from the 1930s until

text: its dissolution

text: in 1991. Over its sixty-year history, this primarily

text: classified

text: military program was responsible for a number of pioneering accomplishments in space flight, including the first

text: intercontinental ballistic missile

text: ), first satellite (

text: Sputnik 1

text: ), first animal in

text: Earth orbit

text: (the dog

text: Laika

text: on

text: Sputnik 2

text: ), first human in space and Earth orbit (

text: cosmonaut

text: Yuri Gagarin

text: on

text: Vostok 1

text: ), first woman in space and Earth orbit (

text: cosmonaut

text: Valentina Tereshkova

text: on

text: Vostok 6

text: ), first

text: spacewalk

text: cosmonaut

text: Alexey Leonov

text: on

text: Voskhod 2

text: ), first

text: Moon

text: impact (

text: Luna 2

text: ), first image of the far side of the moon (

text: Luna 3

text: ) and unmanned lunar soft landing (

text: Luna 9

text: ), first

text: space rover

text: Lunokhod 1

text: ), first sample of

text: lunar soil

text: automatically extracted and brought to Earth (

text: Luna 16

text: ), and first

text: space station

text: Salyut 1

text: ). Further notable records included the first

text: interplanetary probe

text: s:

text: Venera 1

text: and

text: Mars 1

text: to fly by

text: Venus

text: and

text: Mars

text: , respectively,

text: Venera 3

text: and

text: Mars 2

text: to impact the respective planet surface, and

text: Venera 7

text: and

text: Mars 3

text: to make soft landings on these planets.

text: Zeeman is a lunar impact crater located on the far side of the Moon near its south pole. It is not directly visible from the Earth. To the northwest of Zeeman lies the crater Numerov. Southeast of the rim is the crater Ashbrook.

text: Zeeman is a

text: lunar

text: impact crater

text: located on the far side of the

text: Moon

text: near its south pole. It is not directly visible from the

text: Earth

text: . To the northwest of Zeeman lies the crater

text: Numerov

text: . Southeast of the rim is the crater

text: Ashbrook

text: Carpenter is a lunar impact crater in the northern part of the Moon, relatively close to the limb (as viewed from earth). At this position the crater is foreshortened and appears oval in shape. It is, however, very nearly circular in outline. The outer rampart to the south is adjoined to the old crater Anaximander, and the satellite formation Anaximander B lies along the western rim. To the northeast is Anaximenes.

text: Carpenter is a

text: lunar

text: impact crater

text: in the northern part of the

text: Moon

text: , relatively close to the limb (as viewed from earth). At this position the crater is foreshortened and appears oval in shape. It is, however, very nearly circular in outline. The outer

text: rampart

text: to the south is adjoined to the old crater

text: Anaximander

text: , and the satellite formation Anaximander B lies along the western rim. To the northeast is

text: Anaximenes

text: The Lunar terminator is the division between the illuminated and dark parts of the Moon. It is the lunar equivalent of the division between night and day on the Earth's sphere, although the Moon's much lower rate of rotation means it takes longer for it to pass across the surface.

text: The Lunar terminator is the division between the illuminated and dark parts of the

text: Moon

text: . It is the lunar equivalent of the division between

text: night

text: and

text: day

text: on the Earth's sphere, although the Moon's much lower rate of rotation means it takes longer for it to pass across the surface.

text: The college has seen a lot of days where students have had to survive days without water supply in the hostels. The conditions inside the hostels is cringeworthy with lack of maintenance and shortage of water. Toilets and common places often have no cleaners, lights are broken and taps are not in working conditions.

text: In March 1953, the Gilberton Company published a comic-book adaptation of From the Earth to the Moon as issue No. 105 in its Classics Illustrated series.  An unidentified scriptwriter combined Verne's From the Earth to the Moon with the sequel, Around the Moon. Gilberton art director Alex A. Blum supplied both the cover painting and the 44 pages of interior art. The title went through twelve printings between 1953 and 1971.

text: In March 1953, the Gilberton Company published a comic-book adaptation of From the Earth to the Moon as issue No. 105 in its

text: Classics Illustrated

text: series.  An unidentified scriptwriter combined Verne's From the Earth to the Moon with the sequel, Around the Moon. Gilberton art director

text: Alex A. Blum

text: supplied both the cover painting and the 44 pages of interior art. The title went through twelve printings between 1953 and 1971.

text: Weyl is a lunar impact crater that is located on the far side of the Moon, behind the western limb as seen from the Earth. It lies to the east-southeast of the larger crater Fersman. To the southeast is Kamerlingh Onnes, and to the northeast is Shternberg.

text: Weyl is a

text: lunar

text: impact crater

text: that is located on the

text: far side

text: of the

text: Moon

text: , behind the western limb as seen from the

text: Earth

text: . It lies to the east-southeast of the larger crater

text: Fersman

text: . To the southeast is

text: Kamerlingh Onnes

text: , and to the northeast is

text: Shternberg

text: Paul Calle (pronounced KAL-ee; March 3, 1928 – December 30, 2010) was an American artist who was best known for the designs he created for postage stamps, including 40 that were released by the United States Postal Service, and others for stamps issued by the Federated States of Micronesia, the Marshall Islands, Sweden and the United Nations. The sole artist hired by NASA to cover the Apollo 11 astronauts up close, Calle designed the 10-cent stamp that commemorated the first manned moon landing; it depicted an astronaut stepping onto the moon from the lunar module, with the Earth visible over the moon's horizon.

text: Paul Calle (pronounced KAL-ee; March 3, 1928 – December 30, 2010) was an American artist who was best known for the designs he created for postage stamps, including 40 that were released by the

text: United States Postal Service

text: , and others for stamps issued by the

text: Federated States of Micronesia

text: , the

text: Marshall Islands

text: Sweden

text: and the

text: United Nations

text: . The sole artist hired by

text: NASA

text: to cover the

text: Apollo 11

text: astronauts up close, Calle designed the 10-cent stamp that commemorated the first manned moon landing; it depicted an astronaut stepping onto the moon from the lunar module, with the Earth visible over the moon's horizon.

text: The crater interior has a relatively high albedo, making it a prominent feature when the Moon is nearly full. (The high latitude of the crater means that the Sun always remains close to the horizon even at maximum elevation less than a day after Full Moon.) The interior walls are steep and possess a system of terraces. The central peak is offset from the crater midpoint, and joins a low range across the crater floor.  In fact, it appears that some of the central peak material has landed outside the crater rim.

text: The crater interior has a relatively high

text: albedo

text: , making it a prominent feature when the Moon is nearly full. (The high latitude of the crater means that the

text: Sun

text: always remains close to the horizon even at maximum elevation less than a day after Full Moon.) The interior walls are steep and possess a system of

text: terraces

text: . The central peak is offset from the crater midpoint, and joins a low range across the crater floor.  In fact, it appears that some of the central peak material has landed outside the crater rim.

text: Cajori is a lunar crater that is located in the southern hemisphere on the far side of the Moon. It lies to the southwest of the walled plain Von Kármán, and to the east-southeast of the crater Chrétien.

text: Cajori is a

text: lunar

text: crater

text: that is located in the southern

text: hemisphere

text: on the

text: far side

text: of the

text: Moon

text: . It lies to the southwest of the walled plain

text: Von Kármán

text: , and to the east-southeast of the crater

text: Chrétien

text: Störmer is a lunar impact crater that is located on the far side of the Moon from the Earth, named after Carl Størmer, a Norwegian mathematician and aurora researcher. It lies in the northern part of the lunar surface, to the southeast of the crater Olivier and to the north of van Rhijn.

text: Störmer is a

text: lunar

text: impact crater

text: that is located on the

text: far side

text: of the

text: Moon

text: from the

text: Earth

text: , named after

text: Carl Størmer

text: , a Norwegian mathematician and

text: aurora

text: researcher. It lies in the northern part of the lunar surface, to the southeast of the crater

text: Olivier

text: and to the north of

text: van Rhijn

text: The Moon's existence is widely attributed to a huge impact early in Earth's history. Impact events earlier in the history of Earth have been credited with creative as well as destructive events; it has been proposed that impacting comets delivered the Earth's water, and some have suggested that the origins of life may have been influenced by impacting objects by bringing organic chemicals or lifeforms to the Earth's surface, a theory known as exogenesis.

text: The

text: Moon

text: 's existence is widely attributed to a

text: huge impact early in Earth's history

text: . Impact events earlier in the

text: history of Earth

text: have been credited with creative as well as destructive events; it has been proposed that impacting comets delivered the Earth's water, and some have suggested that the

text: origins of life

text: may have been influenced by impacting objects by bringing organic chemicals or lifeforms to the Earth's surface, a theory known as

text: exogenesis

text: Since 1936, Escher’s work had become primarily focused on paradoxes, tessellation and other abstract visual concepts. This print, however, is a realistic depiction of a simple image that portrays two perspectives at once. It depicts an unpaved road with a large pool of water in the middle of it at twilight. Turning the print upside-down and focusing strictly on the reflection in the water, it becomes a depiction of a forest with a full moon overhead. The road is soft and muddy and in it there are two distinctly different sets of tire tracks, two sets of footprints going in opposite directions and two bicycle tracks. Escher has thus captured three elements: the water, sky and earth.

text: Since 1936, Escher’s work had become primarily focused on

text: paradoxes

text: tessellation

text: and other abstract visual concepts. This print, however, is a realistic depiction of a simple image that portrays two perspectives at once. It depicts an unpaved road with a large pool of water in the middle of it at twilight. Turning the print upside-down and focusing strictly on the reflection in the water, it becomes a depiction of a forest with a full moon overhead. The road is soft and muddy and in it there are two distinctly different sets of tire tracks, two sets of footprints going in opposite directions and two bicycle tracks. Escher has thus captured three elements: the water, sky and earth.

text: Because the lunar orbit is also inclined to Earth's ecliptic plane by 5.1°, the rotational axis of the Moon seems to rotate towards and away from Earth during one complete orbit. This is referred to as latitudinal libration, which allows one to see almost 7° of latitude beyond the pole on the far side. Finally, because the Moon is only about 60 Earth radii away from Earth's centre of mass, an observer at the equator who observes the Moon throughout the night moves laterally by one Earth diameter. This gives rise to a diurnal libration, which allows one to view an additional one degree's worth of lunar longitude. For the same reason, observers at both of Earth's geographical poles would be able to see one additional degree's worth of libration in latitude.

text: Because the lunar orbit is also inclined to Earth's ecliptic plane by 5.1°, the rotational axis of the Moon seems to rotate towards and away from Earth during one complete orbit. This is referred to as latitudinal libration, which allows one to see almost 7° of latitude beyond the pole on the far side. Finally, because the Moon is only about 60 Earth radii away from Earth's centre of mass, an observer at the equator who observes the Moon throughout the night moves laterally by one Earth diameter. This gives rise to a diurnal libration, which allows one to view an additional one degree's worth of lunar longitude. For the same reason, observers at both of Earth's

text: geographical pole

text: s would be able to see one additional degree's worth of libration in latitude.

text: Plutarch is a lunar impact crater that lies near the north-northeastern limb of the Moon, just to the south of the irregular crater Seneca. To the southeast is the flooded crater Cannon. The proximity of this crater to the limb causes it to appear foreshortened when viewed from the Earth, but it is actually a circular formation.

text: Plutarch is a

text: lunar

text: impact crater

text: that lies near the north-northeastern limb of the

text: Moon

text: , just to the south of the irregular crater

text: Seneca

text: . To the southeast is the flooded crater

text: Cannon

text: . The proximity of this crater to the limb causes it to appear foreshortened when viewed from the

text: Earth

text: , but it is actually a circular formation.

text: A central lunar eclipse is a total lunar eclipse during which the moon passes through the centre of the Earth's shadow. These are relatively rare.

text: A central lunar eclipse is a total lunar eclipse during which the moon passes through the centre of the Earth's shadow. These are

text: relatively rare

text: A lunar occultation occurs when the Moon, moving along its orbital path, passes in front of a star or other celestial object, as seen by an observer (normally on the Earth).  A grazing lunar occultation (also lunar grazing occultation, lunar graze, or just graze) occurs when one of the two edges of the moon parallel to its orbital path appears to just touch or graze the object as the moon goes by.  When this happens, a properly positioned observer will see the grazed object disappear and reappear, possibly several times, as mountains and valleys on the edge of the moon pass in front of it.

text: A lunar

text: occultation

text: occurs when the

text: Moon

text: , moving along its orbital path, passes in front of a

text: star

text: or other celestial object, as seen by an observer (normally on the Earth).  A grazing lunar occultation (also lunar grazing occultation, lunar graze, or just graze) occurs when one of the two edges of the moon parallel to its orbital path appears to just touch or graze the object as the moon goes by.  When this happens, a properly positioned observer will see the grazed object disappear and reappear, possibly several times, as mountains and valleys on the edge of the moon pass in front of it.

text: Every 18.6 years, the angle between the moon's orbit and the earth's equator reaches a maximum of 28°36′ (the sum of the Earth's inclination 23°27′ and the Moon's inclination 5°09′). This is called major lunar standstill. Around this time, the moon's latitude will vary from −28°36′ to +28°36′. 9.3 years later, the angle between the moon's orbit and the earth's equator reaches its minimum, 18°20′. This is called a minor lunar standstill.

text: Every 18.6 years, the angle between the moon's orbit and the earth's equator reaches a maximum of 28°36′ (the sum of the Earth's inclination 23°27′ and the Moon's inclination 5°09′). This is called major

text: lunar standstill

text: . Around this time, the moon's latitude will vary from −28°36′ to +28°36′. 9.3 years later, the angle between the moon's orbit and the earth's equator reaches its minimum, 18°20′. This is called a minor lunar standstill.

text: The Moon's regular phases make it a very convenient timepiece, and the periods of its waxing and waning form the basis of many of the oldest calendars. Tally sticks, notched bones dating as far back as 20–30,000 years ago, are believed by some to mark the phases of the Moon.The ~30-day month is an approximation of the lunar cycle.The English noun month and its cognates in other Germanic languages stem from Proto-Germanic *mǣnṓth-, which is connected to the above-mentioned Proto-Germanic *mǣnōn, indicating the usage of a lunar calendar among the Germanic peoples (Germanic calendar) prior to the adoption of a solar calendar. The PIE root of moon, *méhnōt, derives from the PIE verbal root *meh-, "to measure", "indicat[ing] a functional conception of the moon, i.e. marker of the month" (cf. the English words measure and menstrual), and echoing the Moon's importance to many ancient cultures in measuring time (see Latin ''mensis'' and Ancient Greek ''μείς'' (meis) or  (mēn), meaning "month").Most historical calendars are lunisolar. The 7th-century Islamic calendar is an exceptional example of a purely lunar calendar. Months are traditionally determined by the visual sighting of the hilal, or earliest crescent moon, over the horizon.

text: The Moon's regular phases make it a very convenient timepiece, and the periods of its waxing and waning form the basis of many of the oldest calendars.

text: Tally stick

text: s, notched bones dating as far back as 20–30,000 years ago, are believed by some to mark the phases of the Moon.The ~30-day month is an approximation of the

text: lunar cycle

text: .The English noun month and its cognates in other Germanic languages stem from Proto-Germanic *mǣnṓth-, which is connected to the above-mentioned Proto-Germanic *mǣnōn, indicating the usage of a

text: lunar calendar

text: among the

text: Germanic peoples

text: Germanic calendar

text: ) prior to the adoption of a

text: solar calendar

text: . The

text: PIE root

text: of moon, *méhnōt, derives from the PIE verbal root *meh-, "to measure", "indicat[ing] a functional conception of the moon, i.e. marker of the month" (

text: cf.

text: the English words measure and menstrual), and echoing the Moon's importance to many ancient cultures in measuring time (see

text: Latin

text: ''mensis'' and

text: Ancient Greek

text: ''μείς'' (meis) or  (mēn), meaning "month").Most historical calendars are

text: lunisolar

text: . The 7th-century

text: Islamic calendar

text: is an exceptional example of a purely

text: lunar calendar

text: . Months are traditionally determined by the visual sighting of the

text: hilal

text: , or earliest crescent moon, over the horizon.

text: Yin is characterized as slow, soft, yielding, diffuse, cold, wet, and passive; and is associated with water, earth, the moon, femininity, and nighttime.

text: Yin is characterized as slow, soft, yielding, diffuse, cold, wet, and passive; and is associated with water, earth, the moon,

text: femininity

text: , and nighttime.

text: The organization is the creator of World Moon Bounce Day. A global event where both commercial and amateur radio operators bounce signals off the surface of the Moon and back to Earth. World Moon Bounce Day was first celebrated on June 27, 2009 (GMT) with some events starting some hours earlier. Countries around the world participate as the Earth turns and during a 24-hour event the Moon is visible to all countries. In amateur circles, the activities are also known as EME (communications) (Earth-Moon-Earth). The first World Moon Bounce Day had Apollo astronaut Bill Anders as a guest. His interview was bounced off the Moon as part of the activities. The University of Tasmania in Australia with their 26m dish was able to bounce a data signal off the surface of the Moon which was received by a large dish in the Netherlands. The data signal was successfully resolved back to data setting a world record for the lowest power data signal returned from the Moon with a transmit power of 3mW - about 1,000th of the power of a strong flashlight filament globe.

text: The organization is the creator of World Moon Bounce Day. A global event where both commercial and

text: amateur radio

text: operators bounce signals off the surface of the Moon and back to Earth. World Moon Bounce Day was first celebrated on June 27, 2009 (GMT) with some events starting some hours earlier. Countries around the world participate as the Earth turns and during a 24-hour event the Moon is visible to all countries. In amateur circles, the activities are also known as

text: EME (communications)

text: (Earth-Moon-Earth). The first World Moon Bounce Day had Apollo astronaut

text: Bill Anders

text: as a guest. His interview was bounced off the Moon as part of the activities. The

text: University of Tasmania

text: in Australia with their 26m dish was able to bounce a data signal off the surface of the Moon which was received by a large dish in the Netherlands. The data signal was successfully resolved back to data setting a world record for the lowest power data signal returned from the Moon with a transmit power of 3mW - about 1,000th of the power of a strong flashlight filament globe.

text: For almost five millennia, the geocentric model of the Earth as the center of the universe had been accepted by all but a few astronomers. In Aristotle's cosmology, Earth's central location was perhaps less significant than its identification as a realm of imperfection, inconstancy, irregularity and change, as opposed to the "heavens", (Moon, Sun, planets, stars) which were regarded as perfect, permanent, unchangeable, and in religious thought, the realm of heavenly beings. The Earth was even composed of different material, the four elements "earth", "water", "fire", and "air", while sufficiently far above its surface (roughly the Moon's orbit), the heavens were composed of different substance called "aether". The heliocentric model that replaced it involved not only the radical displacement of the earth to an orbit around the sun, but its sharing a placement with the other planets implied a universe of heavenly components made from the same changeable substances as the Earth. Heavenly motions no longer needed to be governed by a theoretical perfection, confined to circular orbits.

text: For almost five

text: millennia

text: , the

text: geocentric model

text: of the Earth as the center of the universe had been accepted by all but a few astronomers. In Aristotle's cosmology, Earth's central location was perhaps less significant than its identification as a realm of imperfection, inconstancy, irregularity and change, as opposed to the "heavens", (Moon, Sun, planets, stars) which were regarded as perfect, permanent, unchangeable, and in religious thought, the realm of heavenly beings. The Earth was even composed of different material, the four elements "earth", "water", "fire", and "air", while sufficiently far above its surface (roughly the Moon's orbit), the heavens were composed of different substance called "aether". The

text: heliocentric model

text: that replaced it involved not only the radical displacement of the earth to an orbit around the sun, but its sharing a placement with the other planets implied a universe of heavenly components made from the same changeable substances as the Earth. Heavenly motions no longer needed to be governed by a theoretical perfection, confined to circular orbits.

text: Klaproth is an old lunar crater that lies in the rugged southern highlands of the Moon's near side. Due to its location, this crater appears significantly foreshortened when viewed from the Earth. The southern rim of the crater is overlain by the similar-sized crater Casatus, and to the north-northeast lies Blancanus.

text: Klaproth is an old

text: lunar

text: crater

text: that lies in the rugged southern highlands of the

text: Moon

text: 's near side. Due to its location, this crater appears significantly foreshortened when viewed from the

text: Earth

text: . The southern rim of the crater is overlain by the similar-sized crater

text: Casatus

text: , and to the north-northeast lies

text: Blancanus

text: In his speech that opens the episode, the Lunar Controller states that the Moon is home to about 4,000 humans. In Tony Barwick's original script, the character was then to discuss the self-sufficiency of lunar bases in greater detail, stating, for example, "We were all born on Earth, but I see a future where men will be born, spend their lives and die on the Moon." This dialogue was edited out of the finished episode. The appearance of the Moonmobiles that feature in "Lunarville 7" and its sequel, "Crater 101", influenced the design of the SHADO Moonmobiles that would appear in the later Century 21 TV series, UFO. The incidental music for this episode makes extensive use of an Ondes Martenot, played by composer Barry Gray himself, for sequences set in and around Lunarville 7. The music was recorded in the same studio session as that for "The Launching", on  with four instrumentalists in attendance.

text: In his speech that opens the episode, the Lunar Controller states that the

text: Moon

text: is home to about 4,000 humans. In

text: Tony Barwick

text: 's original script, the character was then to discuss the self-sufficiency of

text: lunar base

text: s in greater detail, stating, for example, "We were all born on Earth, but I see a future where men will be born, spend their lives and die on the Moon." This dialogue was edited out of the finished episode. The appearance of the Moonmobiles that feature in "Lunarville 7" and its sequel, "

text: Crater 101

text: ", influenced the design of the SHADO Moonmobiles that would appear in the later

text: Century 21

text: TV series,

text: UFO

text: . The

text: incidental music

text: for this episode makes extensive use of an

text: Ondes Martenot

text: , played by composer

text: Barry Gray

text: himself, for sequences set in and around Lunarville 7. The music was recorded in the same studio session as that for "

text: The Launching

text: ", on  with four instrumentalists in attendance.

text: Oken is a lunar crater near the southeastern limb of the Moon. It is normally visible from the Earth, but is foreshortened and within the region of the surface that is subject to libration. To the south and east of this feature is the broad, uneven Mare Australe, which extends to the far side of the Moon.

text: Oken is a

text: lunar

text: crater

text: near the southeastern limb of the

text: Moon

text: . It is normally visible from the

text: Earth

text: , but is foreshortened and within the region of the surface that is subject to

text: libration

text: . To the south and east of this feature is the broad, uneven

text: Mare Australe

text: , which extends to the

text: far side

text: of the Moon.

text: This is the average period of the Moon's revolution with respect to the line joining the Sun and Earth. The synodic month is the period of the Moon's phases, because the Moon's appearance depends on the position of the Moon with respect to the Sun as seen from the Earth.

text: This is the average period of the Moon's revolution with respect to the line joining the Sun and Earth. The synodic month is the period of the Moon's

text: phases

text: , because the Moon's appearance depends on the position of the Moon with respect to the Sun as seen from the Earth.

text: The remains of five S-IVB third stages of Saturn V rockets from the Apollo program are the heaviest single pieces sent to the Lunar surface. Humans have left over  of material on the Moon, and  of Moon rock was brought back to Earth by Apollo and Luna missions. The only artificial objects on the Moon that are still in use are the retroreflectors for the lunar laser ranging experiments left there by the Apollo 11, 14, and 15 astronauts and by the Lunokhod 1 and Lunokhod 2 missions.

text: The remains of five

text: S-IVB

text: third stages of

text: Saturn V

text: rockets from the Apollo program are the heaviest single pieces sent to the Lunar surface. Humans have left over  of material on the Moon, and  of

text: Moon rock

text: was brought back to Earth by Apollo and

text: Luna

text: missions. The only artificial objects on the Moon that are still in use are the retroreflectors for the

text: lunar laser ranging experiment

text: s left there by the

text: Apollo 11

text: , 14, and 15 astronauts and by the

text: Lunokhod 1

text: and

text: Lunokhod 2

text: missions.

text: In his continuing career, Saitō has become the most experienced blue-water yachtsman from Japan with transoceanic voyages totaling more than  — almost exactly the distance to the moon. He has started and finished eight solo circumnavigations of the Earth, the seventh one non-stop, achieving several international honors and world records.

text: Earthshine is most readily observable from shortly before until shortly after a new moon, during the waxing or waning crescent phase.  When the Moon is new as viewed from Earth, Earth is nearly fully lit up as viewed from the Moon. Sunlight is reflected from the Earth to the night side of the Moon.  The night side appears to glow faintly and the entire orb of the Moon is dimly visible.

text: Earthshine is most readily observable from shortly before until shortly after a

text: new moon

text: , during the waxing or waning crescent phase.  When the Moon is new as viewed from

text: Earth

text: , Earth is nearly fully lit up as viewed from the Moon.

text: Sunlight

text: is reflected from the Earth to the night side of the Moon.  The night side appears to glow faintly and the entire orb of the Moon is dimly visible.

text: A fourth influence occurs because the orbit of the moon around the earth and the orbit the of the earth around the sun are elliptical rather than circular. The effect of this is that the time between high tides changes a little from day to day. The moon takes about 24.8 hours to orbit around the earth, so it takes half this time, 12.4 hours, for the M2 tides to occur. The tides can be predicted far in advance, because the moon and earth have orbits that are predictable. The National Institute of Water and Atmospheric Research (NIWA) run a tidal computer model specific to New Zealand.

text: A fourth influence occurs because the orbit of the moon around the earth and the orbit the of the earth around the sun are

text: elliptical

text: rather than circular. The effect of this is that the time between high tides changes a little from day to day. The moon takes about 24.8 hours to orbit around the earth, so it takes half this time, 12.4 hours, for the M2 tides to occur. The tides can be predicted far in advance, because the moon and earth have orbits that are predictable. The

entity_name: National Institute of Water and Atmospheric Research

text: National Institute of Water and Atmospheric Research

text: (NIWA) run a tidal computer model specific to New Zealand.

text: Many factors can affect the appearance of the Moon during a lunar eclipse.  The Moon's path through the Earth's umbra is important, but so too are the current conditions of the Earth's atmosphere.  While the Earth's shadow blocks any direct light from striking the Moon during a lunar eclipse, some light is refracted through the Earth's atmosphere giving a Moon a red hue.

text: Many factors can affect the appearance of the Moon during a lunar eclipse.  The Moon's path through the Earth's

text: umbra

text: is important, but so too are the current conditions of the

text: Earth's atmosphere

text: .  While the Earth's shadow blocks any direct light from striking the Moon during a lunar eclipse, some light is refracted through the Earth's atmosphere giving a Moon a red hue.

text: While the giant impact hypothesis might explain many lines of evidence, there are still some unresolved questions, most of which involve the Moon's composition.In 2001, a team at the Carnegie Institute of Washington reported the most precise measurement of the isotopic signatures of lunar rocks. To their surprise, the team found that the rocks from the Apollo program carried an isotopic signature that was identical with rocks from Earth, and were different from almost all other bodies in the Solar System. Because most of the material that went into orbit to form the Moon was thought to come from Theia, this observation was unexpected. In 2007, researchers from the California Institute of Technology announced that there was less than a 1% chance that Theia and Earth had identical isotopic signatures. Published in 2012, an analysis of titanium isotopes in Apollo lunar samples showed that the Moon has the same composition as Earth, which conflicts with what is expected if the Moon formed far from Earth's orbit or from Theia. Variations on the giant impact hypothesis may explain this data.

text: While the giant impact hypothesis might explain many lines of evidence, there are still some unresolved questions, most of which involve the Moon's composition.In 2001, a team at the Carnegie Institute of Washington reported the most precise measurement of the isotopic signatures of lunar rocks. To their surprise, the team found that the rocks from the

text: Apollo program

text: carried an isotopic signature that was identical with rocks from Earth, and were different from almost all other bodies in the Solar System. Because most of the material that went into orbit to form the Moon was thought to come from

text: Theia

text: , this observation was unexpected. In 2007, researchers from the California Institute of Technology announced that there was less than a 1% chance that Theia and Earth had identical isotopic signatures. Published in 2012, an analysis of titanium isotopes in Apollo lunar samples showed that the Moon has the same composition as Earth, which

text: conflicts

text: with what is expected if the Moon formed far from Earth's orbit or from Theia. Variations on the giant impact hypothesis may explain this data.

text: Peirescius is a lunar impact crater that is located in the southeastern part of the Moon. It is close enough to the limb that it appears significantly foreshortened when viewed from the Earth, even though it is nearly circular in shape. To the west-northwest of Peirescius is the crater Vega, and less than one crater diameter to the south is Brisbane. Farther to the east is the Mare Australe.

text: Peirescius is a

text: lunar

text: impact crater

text: that is located in the southeastern part of the

text: Moon

text: . It is close enough to the limb that it appears significantly foreshortened when viewed from the

text: Earth

text: , even though it is nearly circular in shape. To the west-northwest of Peirescius is the crater

text: Vega

text: , and less than one crater diameter to the south is

text: Brisbane

text: . Farther to the east is the

text: Mare Australe

text: The lunar maria  (singular: mare ) are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and hence appear dark to the naked eye. The maria cover about 16 percent of the lunar surface, mostly on the side visible from Earth. The few maria on the far side are much smaller, residing mostly in very large craters. The traditional nomenclature for the Moon also includes one oceanus (ocean), as well as features with the names lacus (lake), palus (marsh), and sinus (bay). The last three are smaller than maria, but have the same nature and characteristics.

text: The lunar maria  (singular: mare ) are large, dark,

text: basalt

text: ic plains on

text: Earth

text: 's

text: Moon

text: , formed by ancient

text: volcanic

text: eruptions. They were dubbed maria,

text: Latin

text: for "seas", by early astronomers who mistook them for actual

text: sea

text: s. They are less reflective than the "highlands" as a result of their iron-rich compositions, and hence appear dark to the naked eye. The maria cover about 16 percent of the lunar surface, mostly on the side visible from Earth. The few maria on the far side are much smaller, residing mostly in very large craters. The traditional nomenclature for the Moon also includes one oceanus (ocean), as well as features with the names lacus (lake), palus (marsh), and sinus (bay). The last three are smaller than maria, but have the same nature and characteristics.

text: During ashfall events large demands are commonly placed on water resources for cleanup and shortages can result. Shortages compromise key services such as firefighting and can lead to a lack of water for hygiene, sanitation and drinking. Municipal authorities need to monitor and manage this water demand carefully, and may need to advise the public to utilise cleanup methods that do not use water (e.g., cleaning with brooms rather than hoses).

text: The first part of the film — popular science — tells of recent (mid-1960s) achievements in the exploration of the Moon. Scientists discuss the hypothesis of the origin of the lunar maria, about the temperature of the lunar surface and the supposed properties of the lunar soil.

text: The first part of the film — popular science — tells of recent (mid-1960s) achievements in the exploration of the Moon. Scientists discuss the hypothesis of the origin of the

text: lunar maria

text: , about the temperature of the lunar surface and the supposed properties of the

text: lunar soil

text: When the Earth, moon, and sun are in line (sun–Earth–moon, or sun–moon–Earth) the two main influences combine to produce spring tides; when the two forces are opposing each other as when the angle moon–Earth–sun is close to ninety degrees, neap tides result. As the moon moves around its orbit it changes from north of the equator to south of the equator. The alternation in high tide heights becomes smaller, until they are the same (at the lunar equinox, the moon is above the equator), then redevelop but with the other polarity, waxing to a maximum difference and then waning again.

text: During a meteor shower said to be the most spectacular in 10,000 years, an asteroid hidden by the meteor field strikes the Moon. Fragments of the asteroid and of the Moon itself penetrate Earth's atmosphere and make impact.  The initial damage is minimal, though significant physical damage to the lunar surface can be seen from Earth.  Experts believe that the Moon has stabilized into a slightly closer orbit. Then strange anomalies begin to manifest themselves on Earth, including cell phone disruptions, unusual static discharges and odd tidal behavior. The world's leading scientists, including Alex Kittner, Maddie Rhodes, and Roland Emerson, begin piecing together evidence that suggests the moon's properties have been permanently altered because the asteroid that hit the Moon was actually a fragment of a brown dwarf; the fragment is highly magnetized and more massive than the Earth despite being only 19 kilometers across, and it is still inside the moon.  When the Moon's new, more elliptical orbit brings it closer to Earth, electromagnetic surges begin affecting the surface, causing people, vehicles, and other objects to levitate at random, worldwide.  Alex, Maddie, Roland and the rest of their team soon discover that the Moon's new orbit will cause it to collide with the Earth in 39 days, completely destroying the planet.  After a failed attempt by the United States to destroy the Moon with nuclear weapons, the three scientists plan an international mission to the Moon, where astronauts must construct a device to magnetize the Moon's core, causing it to disgorge the embedded brown dwarf fragment, eliminating the magnetic effects and restoring the Moon to a stable orbit.  Because of their unique expertise, Alex and Roland must join an American astronaut and a Russian cosmonaut on the mission, which is expected to be a one-way trip.

text: During a

text: meteor shower

text: said to be the most spectacular in 10,000 years, an

text: asteroid

text: hidden by the meteor field strikes the

text: Moon

text: . Fragments of the asteroid and of the Moon itself penetrate Earth's

text: atmosphere

text: and make impact.  The initial damage is minimal, though significant physical damage to the

text: lunar surface

text: can be seen from Earth.  Experts believe that the Moon has stabilized into a slightly closer orbit. Then strange anomalies begin to manifest themselves on Earth, including

text: cell phone

text: disruptions, unusual

text: static discharges

text: and odd

text: tidal behavior

text: . The world's leading scientists, including Alex Kittner, Maddie Rhodes, and Roland Emerson, begin piecing together evidence that suggests the moon's properties have been permanently altered because the asteroid that hit the Moon was actually a fragment of a

text: brown dwarf

text: ; the fragment is highly magnetized and more massive than the Earth despite being only 19 kilometers across, and it is still inside the moon.  When the Moon's new, more elliptical orbit brings it closer to Earth,

text: electromagnetic

text: surges begin affecting the surface, causing people, vehicles, and other objects to levitate at random, worldwide.  Alex, Maddie, Roland and the rest of their team soon discover that the Moon's new orbit will cause it to collide with the Earth in 39 days, completely destroying the planet.  After a failed attempt by the

text: United States

text: to destroy the Moon with nuclear weapons, the three scientists plan an international mission to the Moon, where

text: astronauts

text: must construct a device to magnetize the Moon's core, causing it to disgorge the embedded brown dwarf fragment, eliminating the magnetic effects and restoring the Moon to a stable orbit.  Because of their unique expertise, Alex and Roland must join an American astronaut and a Russian cosmonaut on the mission, which is expected to be a one-way trip.

text: On the near side of the Moon, the strength-to-density required of the tether of a lunar space elevator exists in currently available materials. A lunar space elevator would be about  long. Since the Moon does not rotate fast enough, there is no effective lunar-stationary orbit, but the Lagrangian points could be used. The near side would extend through the Earth-Moon L1 point from an anchor point near the center of the visible part of Earth's Moon.

text: On the near side of the Moon, the strength-to-density required of the tether of a

text: lunar space elevator

text: exists in currently available materials. A lunar space elevator would be about  long. Since the Moon does not rotate fast enough, there is no effective lunar-stationary orbit, but the

text: Lagrangian point

text: s could be used. The near side would extend through the Earth-Moon

text: point from an anchor point near the center of the visible part of Earth's Moon.

text: There was also a region on the Lunar farside that was briefly misidentified as a mare and named Mare Desiderii (Sea of Dreams). It is no longer recognized. Other former maria include:

text: Mare Desiderii

text: (Sea of Dreams). It is no longer recognized. Other former maria include:

text: In 2011, planetary scientists Erik Ahsphaug and Martin Jutzi published a study proposing that the uneven distribution of maria occurred because the moon collided with another, smaller moon of the earth, a few million years after its formation. In this low-impact collision, the smaller moon was crushed into the surface of the moon, thickening the moon's crust on one side. Subsequent impacts broke through the crust and released lava only where the crust was thin, leading to the observed uneven distribution of maria.

text: Boussingault is a large lunar crater that lies near the rugged southeast limb of the Moon. Because of its location, Boussingault appears highly oblong in shape due to foreshortening. To the southwest is the crater Boguslawsky, and almost attached to the northeast rim is Helmholtz. East-southeast of Boussingault lies the crater Neumayer.

text: Boussingault is a large

text: lunar

text: crater

text: that lies near the rugged southeast limb of the

text: Moon

text: . Because of its location, Boussingault appears highly oblong in shape due to foreshortening. To the southwest is the crater

text: Boguslawsky

text: , and almost attached to the northeast rim is

text: Helmholtz

text: . East-southeast of Boussingault lies the crater

text: Neumayer

text: Residing in Earth's first moon (during the events of Kill the Moon), these creatures are bacteria that have taken the form of spiders and can produce webbing similar to actual ones. Sunlight will burn these creatures, so they seek darkness or remain below the moon's surface. They can be killed by ordinary cleaning supplies.

text: Residing in Earth's first moon (during the events of

text: Kill the Moon

text: ), these creatures are bacteria that have taken the form of spiders and can produce webbing similar to actual ones. Sunlight will burn these creatures, so they seek darkness or remain below the moon's surface. They can be killed by ordinary cleaning supplies.

text: Many places on Mars show channels of different sizes.  Many of these channels probably carried water, at least for a time.  The climate of Mars may have been such in the past that water ran on its surface.  It has been known for some time that Mars undergoes many large changes in its tilt or obliquity because its two small moons lack the gravity to stabilize it, as our moon stabilizes Earth; at times the tilt has even been greater than 80 degrees

text: Controlling the location of impact for spent lunar orbiters can have scientific value. For example, in 1999 the NASA Lunar Prospector orbiter was deliberately targeted to impact a permanently shadowed area of Shoemaker Crater near the lunar south pole. It was hoped that energy from the impact would vaporize suspected shadowed ice deposits in the crater and liberate a water vapor plume that would be detectable from Earth. No such plume was observed. However, a small vial of ashes from the body of pioneer lunar scientist Eugene Shoemaker was delivered by the Lunar Prospector to the crater named in his honor – currently the only human remains on the Moon.

text: Controlling the location of impact for spent lunar orbiters can have scientific value. For example, in 1999 the NASA

text: Lunar Prospector

text: orbiter was deliberately targeted to impact a permanently shadowed area of Shoemaker Crater near the lunar south pole. It was hoped that energy from the impact would vaporize suspected shadowed ice deposits in the crater and liberate a water vapor plume that would be detectable from Earth. No such plume was observed. However, a small vial of ashes from the body of pioneer lunar scientist

text: Eugene Shoemaker

text: was delivered by the Lunar Prospector to the crater named in his honor – currently the only human remains on the Moon.

text: Moon gardeners maintain that not only is science on their side, but also that the results are plain to see. According to the theory, plants that are sown in the few days before a full moon become stronger and more productive. The moon gardeners claim that the gravitational force of the full moon affects the level of groundwater in the soil, just as it does the level of the oceans. With more water being drawn up into the soil during a full moon, any newly sown seeds are boosted by the increased hydration. It should be noted that the phases of the moon do not correspond to the distance of the moon's orbit around the Earth, and hence are not indicators of the strength of the moon's gravitational pull. Instead, apogee and perigee of the moon's orbit are what determines the moon's distance to the Earth.

text: Moon gardeners maintain that not only is science on their side, but also that the results are plain to see. According to the theory, plants that are sown in the few days before a full moon become stronger and more productive. The moon gardeners claim that the

text: gravitational force

text: of the full moon affects the

text: level of groundwater

text: in the soil, just as it does the level of the oceans. With more water being drawn up into the soil during a full moon, any newly sown seeds are boosted by the increased hydration. It should be noted that the phases of the moon do not correspond to the distance of the moon's orbit around the Earth, and hence are not indicators of the strength of the moon's gravitational pull. Instead, apogee and perigee of the moon's orbit are what determines the moon's distance to the Earth.

text: The traditional authorities of this people are organized in a system based on civil and religious roles, in which advice from elders is treated as the greatest authority. They believe in the Holy Grandmother, the Holy Father Sun, the Holy Mother Earth, and the Holy Mother Moon. In addition, they worship the deities of water, wind, rain, the mountain, and fire.

text: Elger is a lunar crater that lies along the southern edge of Palus Epidemiarum, the Marsh of Epidemics, in the southwest part of the Moon's near side. To the northeast is the flooded crater Capuanus, and farther to the northwest is Ramsden.

text: Elger is a

text: lunar

text: crater

text: that lies along the southern edge of

text: Palus Epidemiarum

text: , the Marsh of Epidemics, in the southwest part of the

text: Moon

text: 's near side. To the northeast is the flooded crater

text: Capuanus

text: , and farther to the northwest is

text: Ramsden

text: Another hypothesis attributes the formation of the Moon to the impact of a large asteroid with the Earth much later than previously thought, creating the satellite primarily from debris from Earth. In this hypothesis, the formation of the Moon occurs 60–140 million years after the formation of the Solar System. Previously, the age of the Moon had been thought to be 4.527 ± 0.010 billion years. The impact in this scenario would have created a magma ocean on Earth and the proto-Moon with both bodies sharing a common plasma metal vapour atmosphere. The shared metal vapour bridge would have allowed material from the Earth and proto-Moon to exchange and equilibrate into a more common composition.

text: Kircher is a lunar crater that is located in the south-southwestern part of the Moon, near the southern limb. In this position the crater appears foreshortened when viewed from the Earth. It is less than one crater diameter due south of the crater Bettinus, and is nearly attached to Wilson along the south-southeast rim of Kircher.

text: Kircher is a

text: lunar

text: crater

text: that is located in the south-southwestern part of the

text: Moon

text: , near the southern limb. In this position the crater appears foreshortened when viewed from the

text: Earth

text: . It is less than one crater diameter due south of the crater

text: Bettinus

text: , and is nearly attached to

text: Wilson

text: along the south-southeast rim of Kircher.

text: Pasteur is a large lunar crater belonging to the category termed a walled plain. It lies on the far side of the Moon as seen from the Earth, just beyond the eastern limb. The vicinity of this crater is occasionally brought into view from Earth due to librations, although not much detail can be seen.

text: Pasteur is a large

text: lunar

text: crater

text: belonging to the category termed a walled plain. It lies on the

text: far side

text: of the

text: Moon

text: as seen from the

text: Earth

text: , just beyond the eastern limb. The vicinity of this crater is occasionally brought into view from Earth due to

text: libration

text: s, although not much detail can be seen.

text: The Weak Equivalence Principle says that all objects fall the same way in a gravity field, no matter what they are made of. The Earth and the Moon have very different compositions—for example, the Earth has a large iron core, but the Moon does not. Furthermore, both are in orbit around the Sun, meaning they are both falling towards the Sun at all times, even as they revolve around each other. If the Earth and the Moon were affected differently by the gravity of the Sun, this would directly affect the orbit of the Moon around the Earth. But as closely as scientists can measure, the orbit of the Moon is just as predicted from assuming that gravity acts the same on each — to within 1 part in , the Earth and the Moon fall towards the Sun in exactly the same way, despite their different compositions. APOLLO will lead to even tighter limits.

text: The Weak Equivalence Principle says that all objects fall the same way in a gravity field, no matter what they are made of. The Earth and the Moon have very different compositions—for example, the Earth has a

text: large iron core

text: , but the Moon does not. Furthermore, both are in orbit around the Sun, meaning they are both falling towards the Sun at all times, even as they revolve around each other. If the Earth and the Moon were affected differently by the gravity of the Sun, this would directly affect the orbit of the Moon around the Earth. But as closely as scientists can measure, the orbit of the Moon is just as predicted from assuming that gravity acts the same on each — to within 1 part in , the Earth and the Moon fall towards the Sun in exactly the same way, despite their different compositions. APOLLO will lead to even tighter limits.

text: The Moon, which orbits Earth rather than the Sun, is in opposition to the Sun at full moon. When it is in exact opposition, a lunar eclipse occurs.

text: The

text: Moon

text: , which orbits Earth rather than the Sun, is in opposition to the Sun at

text: full moon

text: . When it is in exact opposition, a

text: lunar eclipse

text: occurs.

text: Moonlight photography (taking pictures of the surface of the Earth as illuminated by moonlight) is very different from lunar photography (taking pictures of the surface of the Moon as illuminated by sunlight). The Moon has an effective albedo of approximately 0.12, comparable to fresh asphalt. Since it is essentially a dark rock in full sunlight, photographing its surface needs an exposure comparable to what a photographer would use for ordinary mid-brightness surfaces (buildings, trees, faces, etc.) with an overcast sky.

text: Moonlight photography (taking pictures of the surface of the Earth as illuminated by moonlight) is very different from lunar photography (taking pictures of the surface of the Moon as illuminated by sunlight). The Moon has an effective

text: albedo

text: of approximately 0.12, comparable to fresh asphalt. Since it is essentially a dark rock in full sunlight, photographing its surface needs an exposure comparable to what a photographer would use for ordinary mid-brightness surfaces (buildings, trees, faces, etc.) with an overcast sky.

text: Helberg is a lunar crater that is located just behind the western limb of the Moon, on the far side from the Earth. Due to libration this part of the surface is sometimes brought into view, and the crater is visible under suitable lighting conditions. However even under these circumstances the crater is viewed from the edge and not much detail can be seen.

text: Helberg is a

text: lunar

text: crater

text: that is located just behind the western limb of the

text: Moon

text: , on the

text: far side

text: from the

text: Earth

text: . Due to

text: libration

text: this part of the surface is sometimes brought into view, and the crater is visible under suitable lighting conditions. However even under these circumstances the crater is viewed from the edge and not much detail can be seen.

text: Hohmann is a lunar crater that lies within the central basin of the Mare Orientale formation, on the farside of the Moon. It is located to the south of the crater Maunder, and to the west of Kopff crater. Due to its proximity to the western lunar limb, this area of the surface is occasionally visible during favorable librations. However the basin is viewed from the side, restricting the amount of detail that can be observed from Earth.

text: Hohmann is a

text: lunar

text: crater

text: that lies within the central basin of the

text: Mare Orientale

text: formation, on the

text: farside

text: of the

text: Moon

text: . It is located to the south of the crater

text: Maunder

text: , and to the west of

text: Kopff

text: crater. Due to its proximity to the western lunar limb, this area of the surface is occasionally visible during favorable

text: libration

text: s. However the basin is viewed from the side, restricting the amount of detail that can be observed from

text: Earth

text: Due to tidal acceleration, the orbit of the Moon around the Earth becomes about 2.2 cm more distant each year. It is estimated that, in slightly less than 1.4 billion years, the distance from the Earth to the Moon will have increased by 30,400 km. During that period, the apparent angular diameter of the Moon will decrease in size, meaning that it will no longer be able to completely cover the Sun's disk as seen from the Earth. This will be true even when the Moon is at perigee, and the Earth at aphelion. Moreover, the Sun is increasing in diameter by about 5% per billion years. Therefore, the last total solar eclipse on Earth will occur about six hundred million years from now.

text: Due to

text: tidal acceleration

text: , the orbit of the Moon around the Earth becomes about 2.2 cm more distant each year. It is estimated that, in slightly less than 1.4 billion years, the distance from the Earth to the Moon will have increased by 30,400 km. During that period, the apparent angular diameter of the Moon will decrease in size, meaning that it will no longer be able to completely cover the Sun's disk as seen from the Earth. This will be true even when the Moon is at

text: perigee

text: , and the Earth at

text: aphelion

text: . Moreover, the Sun is increasing in diameter by about 5% per billion years. Therefore, the last total solar eclipse on Earth will occur about six hundred million years from now.

text: A Trip to the Moon () is a 1902 French silent film directed by Georges Méliès. Inspired by a wide variety of sources, including Jules Verne's novels From the Earth to the Moon and Around the Moon, the film follows a group of astronomers who travel to the Moon in a cannon-propelled capsule, explore the Moon's surface, escape from an underground group of Selenites (lunar inhabitants), and return to Earth with a captive Selenite. It features an ensemble cast of French theatrical performers, led by Méliès himself in the main role of Professor Barbenfouillis, and is filmed in the overtly theatrical style for which Méliès became famous.

text: A Trip to the Moon () is a 1902 French

text: silent film

text: directed by

text: Georges Méliès

text: . Inspired by a wide variety of sources, including

text: Jules Verne

text: 's novels

text: From the Earth to the Moon

text: and

text: Around the Moon

text: , the film follows a group of astronomers who travel to the

text: Moon

text: in a cannon-propelled capsule, explore the Moon's surface, escape from an underground group of Selenites (lunar inhabitants), and return to Earth with a captive Selenite. It features an

text: ensemble cast

text: of French theatrical performers, led by Méliès himself in the main role of Professor Barbenfouillis, and is filmed in the overtly theatrical style for which Méliès became famous.

text: The rotational angular momentum of Earth decreases and consequently the length of the day increases. The net tide raised on Earth by the Moon is dragged ahead of the Moon by Earth's much faster rotation. Tidal friction is required to drag and maintain the bulge ahead of the Moon, and it dissipates the excess energy of the exchange of rotational and orbital energy between Earth and the Moon as heat. If the friction and heat dissipation were not present, the Moon's gravitational force on the tidal bulge would rapidly (within two days) bring the tide back into synchronization with the Moon, and the Moon would no longer recede. Most of the dissipation occurs in a turbulent bottom boundary layer in shallow seas such as the European Shelf around the British Isles, the Patagonian Shelf off Argentina, and the Bering Sea.

text: The rotational angular momentum of Earth decreases and consequently the length of the day increases. The net tide raised on Earth by the Moon is dragged ahead of the Moon by Earth's much faster rotation. Tidal friction is required to drag and maintain the bulge ahead of the Moon, and it dissipates the excess energy of the exchange of rotational and orbital energy between Earth and the Moon as heat. If the friction and heat dissipation were not present, the Moon's gravitational force on the tidal bulge would rapidly (within two days) bring the tide back into synchronization with the Moon, and the Moon would no longer recede. Most of the dissipation occurs in a turbulent bottom boundary layer in shallow seas such as the

text: European Shelf

text: around the

text: British Isles

text: , the

text: Patagonian Shelf

text: off

text: Argentina

text: , and the

text: Bering Sea

text: It is natural to visualize this phenomenon as an abundance of stationary photons within the same ray of light creating the spot on the moon. To allow the image to move from one end of the moon to the other, each photon must move laterally with the movement of the projection. In reality this is not the case, the ray of light is a collection of moving photons and at each instant a different group of photons, detected by the observers eye, are creating the image seen on the surface of the moon. The apparent lateral movement is caused by new photons traveling on a different path from the light source to the moon, caused by the rotation of the source, striking an adjacent position at all instances during the rotation. This is depicted in Figure 3, the movement from point A to point B can be visualized by a collection of photons each travelling along a different trajectory from Earth to the moon. The paradox is resolved to be a result of the geometry of the system causing the illusion of superluminal motion, rather than superluminal motion actually occurring.

text: It is natural to visualize this phenomenon as an abundance of stationary photons within the same ray of light creating the spot on the moon. To allow the image to move from one end of the moon to the other, each photon must move laterally with the movement of the projection. In reality this is not the case, the ray of light is a collection of moving

text: photons

text: and at each instant a different group of photons, detected by the observers eye, are creating the image seen on the surface of the moon. The apparent lateral movement is caused by new photons traveling on a different path from the light source to the moon, caused by the rotation of the source, striking an adjacent position at all instances during the rotation. This is depicted in Figure 3, the movement from point A to point B can be visualized by a collection of photons each travelling along a different trajectory from Earth to the moon. The paradox is resolved to be a result of the geometry of the system causing the illusion of superluminal motion, rather than superluminal motion actually occurring.

text: Harden is a small lunar impact crater that lies in the eastern part of the interior floor of the walled plain Mendeleev. It is located on the far side of the Moon, and cannot been seen from the Earth.

text: Harden is a small

text: lunar

text: impact crater

text: that lies in the eastern part of the interior floor of the walled plain

text: Mendeleev

text: . It is located on the

text: far side

text: of the

text: Moon

text: , and cannot been seen from the

text: Earth

text: The celestial sphere can thus be thought of as a kind of astronomical shorthand, and is applied very frequently by astronomers. For instance, the Astronomical Almanac for 2010 lists the apparent geocentric position of the Moon, 1 Jan 2010 at 0h Terrestrial Time, in equatorial coordinates, as right ascension 6 57 48.86, declination +23° 30' 05".5. Implied in this position is that it is as projected onto the celestial sphere; any observer at any location looking in that direction would see the "geocentric Moon" in the same place against the stars. For many rough uses (for instance, calculating an approximate phase of the Moon), this position, as seen from the Earth's center, is adequate. For applications requiring precision (for instance, calculating the shadow path of an eclipse), the Almanac gives formulae and methods for calculating the topocentric coordinates, that is, as seen from a particular place on the Earth's surface, based on the geocentric position. This greatly abbreviates the amount of detail necessary in such almanacs, as each observer can handle their own specific circumstances.

text: The celestial sphere can thus be thought of as a kind of astronomical

text: shorthand

text: , and is applied very frequently by astronomers. For instance, the

text: Astronomical Almanac

text: for 2010 lists the apparent geocentric position of the

text: Moon

text: , 1 Jan 2010 at 0h

text: Terrestrial Time

text: , in

text: equatorial coordinates

text: , as

text: right ascension

text: 6 57 48.86,

text: declination

text: +23° 30' 05".5. Implied in this position is that it is as projected onto the celestial sphere; any observer at any location looking in that direction would see the "geocentric Moon" in the same place against the stars. For many rough uses (for instance, calculating an approximate phase of the Moon), this position, as seen from the Earth's center, is adequate. For applications requiring precision (for instance, calculating the shadow path of an

text: eclipse

text: ), the Almanac gives formulae and methods for calculating the topocentric coordinates, that is, as seen from a particular place on the Earth's surface, based on the geocentric position. This greatly abbreviates the amount of detail necessary in such almanacs, as each observer can handle their own specific circumstances.

text: In a different gravitational field, for example, on the surface of the Moon, an object can have a significantly different weight than on Earth. The gravity on the surface of the Moon is only about one-sixth as strong as on the surface of the Earth. A one-kilogram mass is still a one-kilogram mass (as mass is an extrinsic property of the object) but the downward force due to gravity, and therefore its weight, is only one-sixth of what the object would have on Earth. So a man of mass 180 pounds weighs only about 30 pounds-force when visiting the Moon.

text: In a different gravitational field, for example, on the surface of the

text: Moon

text: , an object can have a significantly different weight than on Earth. The gravity on the surface of the Moon is only about one-sixth as strong as on the surface of the Earth. A one-kilogram mass is still a one-kilogram mass (as mass is an extrinsic property of the object) but the downward force due to gravity, and therefore its weight, is only one-sixth of what the object would have on Earth. So a man of mass 180

text: pounds

text: weighs only about 30

text: pounds-force

text: when visiting the Moon.

text: Thiessen is a lunar impact crater that lies in the far northern latitudes, on the far side of the Moon. To the west of Thiessen is the younger crater Ricco, and to the south-southwest is Roberts. Farther to the east lies Heymans.

text: Thiessen is a

text: lunar

text: impact crater

text: that lies in the far northern latitudes, on the

text: far side

text: of the

text: Moon

text: . To the west of Thiessen is the younger crater

text: Ricco

text: , and to the south-southwest is

text: Roberts

text: . Farther to the east lies

text: Heymans

text: An eclipse does not happen at every new or full moon, because the plane of the orbit of the Moon around the Earth is tilted with respect to the plane of the orbit of the Earth around the Sun (the ecliptic): so as seen from the Earth, when the Moon is nearest to the Sun (new moon) or at largest distance (full moon), the three bodies usually are not exactly on the same line.

text: An eclipse does not happen at every new or full moon, because the plane of the

text: orbit of the Moon

text: around the Earth is tilted with respect to the plane of the orbit of the Earth around the Sun (the

text: ecliptic

text: ): so as seen from the Earth, when the Moon is nearest to the Sun (new moon) or at largest distance (full moon), the three bodies usually are not exactly on the same line.

text: Cleostratus is a lunar crater near the northwest limb of the Moon. It lies to the northeast of the crater Xenophanes, and west-southwest of the prominent Pythagoras. From the Earth this crater appears highly elongated due to foreshortening.

text: Cleostratus is a

text: lunar

text: crater

text: near the northwest limb of the

text: Moon

text: . It lies to the northeast of the crater

text: Xenophanes

text: , and west-southwest of the prominent

text: Pythagoras

text: . From the

text: Earth

text: this crater appears highly elongated due to foreshortening.

text: On the makeup of the Moon rocks, Kaysing asked: "Why was there never a mention of gold, silver, diamonds or other precious metals on the moon? Wasn't this a viable consideration? Why was this fact never discussed [sic] in the press or by the astronauts?" Geologists realize that gold and silver deposits on Earth are the result of the action of hydrothermal fluids concentrating the precious metals into veins of ore. Since in 1969 water was believed to be absent on the Moon, no geologist would bother discussing the possibility of finding these on the Moon in any great amount.

text: In the game, humanity has colonized the Moon and Mars. However, a 20 trillion ton asteroid has collided with Earth, making it uninhabitable. All that is left of humanity is a small, self-sufficient colony on the surface of the Moon, and a race of mutant humans on Mars. As the commander of Moonbase, it is your job to ensure the survival of mankind by exploring the Solar System for other habitable planets and moons, and ultimately re-establish life on Earth. However, the Martian mutants consider themselves the superior race and want Earth for themselves, meaning a war is inevitable.

text: In the game,

text: humanity

text: has

text: colonized

text: the

text: Moon

text: and

text: Mars

text: . However, a 20 trillion ton

text: asteroid

text: has collided with

text: Earth

text: , making it uninhabitable. All that is left of humanity is a small, self-sufficient colony on the surface of the

text: Moon

text: , and a race of mutant humans on

text: Mars

text: . As the commander of Moonbase, it is your job to ensure the survival of mankind by exploring the

text: Solar System

text: for other habitable planets and moons, and ultimately re-establish life on Earth. However, the

text: Martian

text: mutants consider themselves the superior race and want Earth for themselves, meaning a war is inevitable.

text: Virtanen is a lunar crater that is located to the northeast of the larger crater Sharonov, and to the east of Anderson. Virtanen lies on the far side of the Moon, and cannot be viewed directly from the Earth.

text: Virtanen is a

text: lunar

text: crater

text: that is located to the northeast of the larger crater

text: Sharonov

text: , and to the east of

text: Anderson

text: . Virtanen lies on the

text: far side

text: of the

text: Moon

text: , and cannot be viewed directly from the

text: Earth

text: A spacecraft performs TLI to begin a lunar transfer from a low circular parking orbit around Earth.  The large TLI burn, usually performed by a chemical rocket engine, increases the spacecraft's velocity, changing its orbit from a circular low Earth orbit to a highly eccentric orbit.  As the spacecraft begins coasting on the lunar transfer arc, its trajectory approximates an elliptical orbit about the Earth with an apogee near to the radius of the Moon's orbit.  The TLI burn is sized and timed to precisely target the Moon as it revolves around the Earth.   The burn is timed so that the spacecraft nears apogee as the Moon approaches.  Finally, the spacecraft enters the Moon's sphere of influence, making a hyperbolic lunar swingby.

text: A spacecraft performs TLI to begin a lunar transfer from a low circular

text: parking orbit

text: around

text: Earth

text: .  The large TLI

text: burn

text: , usually performed by a chemical

text: rocket

text: engine, increases the spacecraft's velocity, changing its orbit from a circular

text: low Earth orbit

text: to a highly

text: eccentric orbit

text: .  As the spacecraft begins coasting on the lunar transfer arc, its trajectory approximates an elliptical orbit about the Earth with an

text: apogee

text: near to the radius of the Moon's orbit.  The TLI burn is sized and timed to precisely target the Moon as it revolves around the Earth.   The burn is timed so that the spacecraft nears apogee as the Moon approaches.  Finally, the spacecraft enters the Moon's

text: sphere of influence

text: , making a hyperbolic lunar swingby.

text: Earlier it was assumed that Rhea had a rocky core in the center. However measurements taken during a close flyby by the Cassini orbiter in 2005 (see below) cast this into doubt. In a paper published in 2007 it was claimed that the axial dimensionless moment of inertia coefficient was 0.4. Such a value indicated that Rhea had an almost homogeneous interior (with some compression of ice in the center) while the existence of a rocky core would imply a moment of inertia of about 0.34. In the same year another paper claimed the moment of inertia was about 0.37 implying that Rhea was partially differentiated. A year later yet another paper claimed that the moon may not be in hydrostatic equilibrium meaning that the moment of inertia can not be determined from the gravity data alone. In 2008 an author of the first paper tried to reconcile these three disparate results. He concluded that there is a systematic error in the Cassini radio Doppler data used in the analysis, but after restricting the analysis to a subset of data obtained closest to the moon, he arrived at his old result that Rhea was in hydrostatic equilibrium and had the moment inertia of about 0.4, again implying a homogeneous interior.

text: Earlier it was assumed that Rhea had a rocky core in the center. However measurements taken during a close flyby by the

text: Cassini

text: orbiter in 2005 (see below) cast this into doubt. In a paper published in 2007 it was claimed that the axial dimensionless

text: moment of inertia

text: coefficient was 0.4. Such a value indicated that Rhea had an almost homogeneous interior (with some compression of ice in the center) while the existence of a rocky core would imply a moment of inertia of about 0.34. In the same year another paper claimed the moment of inertia was about 0.37 implying that Rhea was partially differentiated. A year later yet another paper claimed that the moon may not be in hydrostatic equilibrium meaning that the moment of inertia can not be determined from the gravity data alone. In 2008 an author of the first paper tried to reconcile these three disparate results. He concluded that there is a systematic error in the Cassini radio Doppler data used in the analysis, but after restricting the analysis to a subset of data obtained closest to the moon, he arrived at his old result that Rhea was in hydrostatic equilibrium and had the moment inertia of about 0.4, again implying a homogeneous interior.

text: Tacchini is a lunar crater on the northwestern edge of the Mare Smythii, near the eastern limb of the Moon. It lies just to the south of the prominent crater Neper, and was designated Neper K before being given its current name by the IAU. To the west-southwest of Tacchini is the crater pair of Schubert and Back.

text: Tacchini is a

text: lunar

text: crater

text: on the northwestern edge of the

text: Mare Smythii

text: , near the eastern limb of the

text: Moon

text: . It lies just to the south of the prominent crater

text: Neper

text: , and was designated Neper K before being given its current name by the

text: IAU

text: . To the west-southwest of Tacchini is the crater pair of

text: Schubert

text: and

text: Back

text: The book delves into the subject of "The Days Before There Was a Moon", as remembered in tales that Chee Chee the Monkey's grandmother told him when he was little. The story of how the moon was created is closer to science than some of the other fantasy elements of the book. Otho Bludge, the stone-age sculptor, came to be the man on the moon because he was transported on the lump of rock that had broken off the Earth, and became the moon. Alone for many years, the sole human on the Moon, Otho Bludge, weary of rendering his own image as reflected in the water, longed for the sight of another human being. In answer to his longing, he was visited by a vision of Princess Pepiteepa, who poses for him, then fades away.

text: A full moon is the lunar phase that occurs when the Moon is completely illuminated as seen from Earth. This occurs when Earth is located directly between the Sun and the Moon (more exactly, when the ecliptic longitudes of the Sun and Moon differ by 180 degrees). This means that the hemisphere of the Moon that is facing Earth (the near side) is almost fully illuminated by the Sun and appears round (while the far side is almost completely unilluminated). On some occasions at the time of full moon there is also a lunar eclipse so the moon's face appears reddish due to the rayleigh scattering of blue light in Earth's atmosphere.

text: A full moon is the

text: lunar phase

text: that occurs when the

text: Moon

text: is completely illuminated as seen from

text: Earth

text: . This occurs when Earth is located directly between the

text: Sun

text: and the Moon (more exactly, when the

text: ecliptic longitude

text: s of the Sun and Moon differ by 180 degrees). This means that the hemisphere of the Moon that is facing Earth (the

text: near side

text: ) is almost fully illuminated by the Sun and appears round (while the

text: far side

text: is almost completely unilluminated). On some occasions at the time of full moon there is also a

text: lunar eclipse

text: so the moon's face appears reddish due to the

text: rayleigh scattering

text: of blue light in Earth's

text: atmosphere

text: The tortoise is a symbol of wisdom and knowledge, and is able to defend itself on its own. It personifies water, the moon, the Earth, time, immortality, and fertility. Creation is associated with the tortoise and it is also believed that the tortoise bears the burden of the whole world.

text: The tidal force produced by a massive object (Moon, hereafter) on a small particle located on or in an extensive body (Earth, hereafter) is the vector difference between the gravitational force exerted by the Moon on the particle, and the gravitational force that would be exerted on the particle if it were located at the Earth's center of mass. The solar gravitational force on the Earth is on average 179 times stronger than the lunar, but because the Sun is on average 389 times farther from the Earth, its field gradient is weaker. The solar tidal force is 46% as large as the lunar. More precisely, the lunar tidal acceleration (along the Moon–Earth axis, at the Earth's surface) is about 1.1 × 10 g, while the solar tidal acceleration (along the Sun–Earth axis, at the Earth's surface) is about 0.52 × 10 g, where g is the gravitational acceleration at the Earth's surface. Venus has the largest effect of the other planets, at 0.000113 times the solar effect.

text: The

text: tidal force

text: produced by a massive object (Moon, hereafter) on a small particle located on or in an extensive body (Earth, hereafter) is the vector difference between the gravitational force exerted by the Moon on the particle, and the gravitational force that would be exerted on the particle if it were located at the Earth's center of mass. The solar

text: gravitational force

text: on the Earth is on average 179 times stronger than the lunar, but because the Sun is on average 389 times farther from the Earth, its field gradient is weaker. The solar tidal force is 46% as large as the lunar. More precisely, the lunar tidal acceleration (along the Moon–Earth axis, at the Earth's surface) is about 1.1 × 10 g, while the solar tidal acceleration (along the Sun–Earth axis, at the Earth's surface) is about 0.52 × 10 g, where g is the

text: gravitational acceleration

text: at the Earth's surface. Venus has the largest effect of the other planets, at 0.000113 times the solar effect.

text: In contrast, manned vehicles need additional fuel after a lunar landing to enable a return trip back to Earth for the crew. Leaving this massive amount of required Earth-return fuel in lunar orbit until it is used later in the mission is far more efficient than taking such fuel down to the lunar surface in a Moon landing and then hauling it all back into space yet again, working against lunar gravity both ways. Such considerations lead logically to a lunar orbit rendezvous mission profile for a manned Moon landing.

text: In contrast, manned vehicles need additional fuel after a lunar landing to enable a return trip back to Earth for the crew. Leaving this massive amount of required Earth-return fuel in lunar orbit until it is used later in the mission is far more efficient than taking such fuel down to the lunar surface in a Moon landing and then hauling it all back into space yet again, working against lunar gravity both ways. Such considerations lead logically to a

text: lunar orbit rendezvous

text: mission profile for a manned Moon landing.

text: The lunar geological timescale (or selenological timescale) divides the history of Earth's Moon into five generally recognized periods: the Copernican, Eratosthenian, Imbrian (Late and Early epochs), Nectarian, and Pre-Nectarian. The boundaries of this time scale are related to large impact events that have modified the lunar surface, changes in crater form that occur through time, and the size-frequency distribution of craters superposed on geological units. The absolute ages for these periods have been constrained by radiometric dating of samples obtained from the lunar surface. However, there is still much debate concerning the ages of certain key events, because correlating lunar regolith samples with geological units on the Moon is difficult, and most lunar radiometric ages have been highly affected by an intense history of bombardment.

text: The lunar geological timescale (or selenological timescale) divides the history of

text: Earth

text: 's

text: Moon

text: into five generally recognized periods: the

text: Copernican

text: Eratosthenian

text: , Imbrian (

text: Late

text: and

text: Early

text: epochs),

text: Nectarian

text: , and

text: Pre-Nectarian

text: . The boundaries of this time scale are related to large

text: impact event

text: s that have modified the

text: lunar surface

text: , changes in

text: crater

text: form that occur through time, and the size-frequency distribution of craters superposed on geological units. The absolute ages for these periods have been constrained by

text: radiometric dating

text: of samples obtained from the lunar surface. However, there is still much debate concerning the ages of certain key events, because correlating lunar

text: regolith

text: samples with geological units on the Moon is difficult, and most lunar radiometric ages have been highly affected by an intense history of bombardment.

text: Herschel was sure that he had found ample evidence of life on the Moon and compared it to the English countryside. He did not refrain himself from theorising that the other planets were populated, with a special interest in Mars, which was in line with most of his contemporary scientists. At Herschel's time, scientists tended to believe in a plurality of civilised worlds, while most religious thinkers referred to unique properties of the earth. Herschel went so far to speculate that the interior of the sun was populated.

text: Congreve is a lunar crater that is located on the far side of the Moon relative to the Earth, and lies across the lunar equator. It lies to the west-northwest of the massive walled plain Korolev. To the southeast is the crater Icarus, and due north is Zhukovskiy.

text: Congreve is a

text: lunar

text: crater

text: that is located on the

text: far side

text: of the

text: Moon

text: relative to the

text: Earth

text: , and lies across the lunar

text: equator

text: . It lies to the west-northwest of the massive walled plain

text: Korolev

text: . To the southeast is the crater

text: Icarus

text: , and due north is

text: Zhukovskiy

text: Edison is a lunar crater on the far side of the Moon. It is located just behind the north-northeastern limb of the Moon, a region that is sometimes brought into sight from Earth during favorable librations. However even at such times not much detail can be discerned, and the crater is better observed by orbiting spacecraft.

text: Edison is a

text: lunar

text: crater

text: on the

text: far side

text: of the

text: Moon

text: . It is located just behind the north-northeastern limb of the

text: Moon

text: , a region that is sometimes brought into sight from

text: Earth

text: during favorable

text: libration

text: s. However even at such times not much detail can be discerned, and the crater is better observed by orbiting

text: spacecraft

text: Snellius is a lunar crater located near the southeast limb of the Moon.

text: Snellius is a

text: lunar

text: crater

text: located near the southeast limb of the

text: Moon

text: Cabeus is a lunar crater that is located about  from the south pole of the Moon. At this location the crater is seen obliquely from Earth, and it is almost perpetually in deep shadow due to lack of sunlight. Hence, not much detail can be seen of this crater, even from orbit. Through a telescope, this crater appears near the southern limb of the Moon, to the west of the crater Malapert and to the south-southwest of Newton.

text: Cabeus is a

text: lunar

text: crater

text: that is located about  from the

text: south pole

text: of the

text: Moon

text: . At this location the crater is seen obliquely from

text: Earth

text: , and it is almost perpetually in deep shadow due to lack of

text: sunlight

text: . Hence, not much detail can be seen of this crater, even from orbit. Through a

text: telescope

text: , this crater appears near the southern limb of the Moon, to the west of the crater

text: Malapert

text: and to the south-southwest of

text: Newton

text: Artsimovich is a small lunar impact crater located in the western Mare Imbrium of the Earth's Moon. This is a circular crater forming a cup-shaped excavation in the surface of the lunar mare. To the east is the crater Diophantus and to the northeast lies Delisle. Less than 20 kilometers to the north-northeast is the tiny Fedorov. This crater was identified as Diophantus A before being named by the IAU.

text: Artsimovich is a small lunar

text: impact crater

text: located in the western

text: Mare Imbrium

text: of the

text: Earth

text: 's

text: Moon

text: . This is a circular crater forming a cup-shaped excavation in the surface of the

text: lunar mare

text: . To the east is the crater

text: Diophantus

text: and to the northeast lies

text: Delisle

text: . Less than 20 kilometers to the north-northeast is the tiny

text: Fedorov

text: . This crater was identified as Diophantus A before being named by the

text: IAU

text: One very important feature common in east Hellas are piles of material surrounding cliffs.  The formation is called a lobate debris apron (LDA).  Recently, research with the Shallow Radar on the Mars Reconnaissance Orbiter has provided strong evidence that the LDAs are glaciers that are covered with a thin layer of rocks. Large amounts of water ice are believed to be in the LDAs.  Available evidence strongly suggests that the eastern part of Hellas accumulated snow in the past.  When the tilt (obliquity) of Mars increases the southern ice cap releases large amounts of water vapor.  Climate models predict that when this occurs, water vapor condenses and falls where LDAs are located.  The tilt of the earth changes little because our relatively large moon keeps it stable.  The two tiny Martian moons do not stabilize their planet, so the rotational axis of Mars undergoes large variations.  Lobate debris aprons may be a major source of water for future Mars colonists.  Their major advantage over other sources of Martian water are that they can easily mapped from orbit and they are closer to the equator, where manned missions are more likely to land.

text: One very important feature common in east Hellas are piles of material surrounding cliffs.  The formation is called a

text: lobate debris apron

text: (LDA).  Recently, research with the Shallow Radar on the

text: Mars Reconnaissance Orbiter

text: has provided strong evidence that the LDAs are

text: glacier

text: s that are covered with a thin layer of rocks. Large amounts of water ice are believed to be in the LDAs.  Available evidence strongly suggests that the eastern part of Hellas accumulated snow in the past.  When the tilt (obliquity) of Mars increases the southern ice cap releases large amounts of water vapor.  Climate models predict that when this occurs, water vapor condenses and falls where LDAs are located.  The tilt of the earth changes little because our relatively large moon keeps it stable.  The two tiny Martian moons do not stabilize their planet, so the rotational axis of Mars undergoes large variations.  Lobate debris aprons may be a major source of water for future Mars colonists.  Their major advantage over other sources of Martian water are that they can easily mapped from orbit and they are closer to the equator, where manned missions are more likely to land.

text: A supermoon is the coincidence of a full moon or a new moon with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth. The technical name is the perigee-syzygy of the Earth–Moon–Sun system. The term supermoon is not astronomical, but originated in modern astrology. The association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with increased risk of events such as earthquakes and volcanic eruptions, but there is no evidence of such a link.

text: A supermoon is the coincidence of a

text: full moon

text: or a

text: new moon

text: with the closest approach the

text: Moon

text: makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth. The technical name is the perigee-syzygy of the Earth–Moon–Sun system. The term supermoon is not

text: astronomical

text: , but originated in modern

text: astrology

text: . The association of the Moon with both oceanic and

text: crustal tide

text: s has led to claims that the supermoon phenomenon may be associated with increased risk of events such as earthquakes and volcanic eruptions, but there is no evidence of such a link.

text: His scientific interests included seismology, meteorology, astrophysics and theoretical physics. He began his career in seismology with his father. In 1913 he developed a new method for locating the hypocenter of an earthquake and gave an independent verification of discontinuity theory put forward by his father. In 1916 he published an idea of the existence of smaller discontinuities in Earth's crust and mantle. He put forward his own theory about the composition and the formation of the Moon, explosive formation of lunar craters and predicted the existence of Moho layer on the Moon. The existence of Moho layer on the Moon was confirmed in 1969 by seismic measurements done by Apollo 11 crew.

text: His scientific interests included

text: seismology

text: meteorology

text: astrophysics

text: and

text: theoretical physics

text: . He began his career in seismology with his father. In 1913 he developed a new method for locating the

text: hypocenter

text: of an

text: earthquake

text: and gave an independent verification of discontinuity theory put forward by his father. In 1916 he published an idea of the existence of smaller discontinuities in

text: Earth's crust

text: and

text: mantle

text: . He put forward his own theory about the composition and the

text: formation of the Moon

text: , explosive formation of

text: lunar craters

text: and predicted the existence of

text: Moho layer

text: on the

text: Moon

text: . The existence of Moho layer on the Moon was confirmed in 1969 by seismic measurements done by

text: Apollo 11 crew

text: Craters less than about 30 km in diameter were not mapped except for those that are rayed and those occurring in chains and clusters satellitic to larger craters and basins. These satellitic or secondary craters are not distinguished as to relative age or origin. (However, near the southwest map corner, elongate chains are radial to their parent crater Valmiki). In general, secondary craters appear topographically fresher and occur closer to their primary sources than do their lunar counterparts. This effect is probably because the higher gravity field on Mercury compared to the Moon has resulted in higher impact velocities for crater ejecta (Scott, 1977).

text: Craters less than about 30 km in diameter were not mapped except for those that are rayed and those occurring in chains and clusters satellitic to larger craters and basins. These satellitic or secondary craters are not distinguished as to relative age or origin. (However, near the southwest map corner, elongate chains are radial to their parent crater

text: Valmiki

text: ). In general, secondary craters appear topographically fresher and occur closer to their primary sources than do their lunar counterparts. This effect is probably because the higher gravity field on Mercury compared to the Moon has resulted in higher impact velocities for crater ejecta (Scott, 1977).

text:
Summer us the warmth was giving,
Larus over the water was floating,
Only for us the moon was shining,
To us alone on the Earth.

text: Summer us the warmth was giving, <br>

text: Larus

text:
over the water was floating,
Only for us the moon was shining,
To us alone on the Earth.

text: Lunar swirls are enigmatic features found across the Moon's surface, which are characterized by a high albedo, appearing optically immature (i.e. the optical characteristics of a relatively young regolith), and often displaying a sinuous shape. Their curvilinear shape is often accentuated by low albedo regions that wind between the bright swirls.

text: Using the simplified model where the orbit of the Moon around the Earth is circular, Schwaniger found that there exists a free-return trajectory in the plane of the orbit of the Moon which is periodic: after returning to low altitude above the Earth (the perigee radius is a parameter, typically 6555 km) the spacecraft would return to the Moon, etc. This periodic trajectory is counter-rotational (it goes from east to west when near the earth). It has a period of about 650 hours (compare with a sidereal month, which is 655.7 hours, or 27.3 days). Considering the trajectory in an inertial (non-rotating) frame of reference, the perigee occurs directly under the moon when the moon is on one side of the earth. Speed at perigee is about 10.91 km/s. After three days it reaches the moon's orbit, but now more or less on the opposite side of the earth from the moon. After a few more days the craft reaches ifs (first) apogee and begins to fall back toward the earth. But then the moon comes along and attracts the craft. The craft passes on the near side of the moon at a radius of 2150 km (410 km above the surface) and is thrown back outwards where it reaches a second apogee. It then falls back toward the earth, goes around to the first side, and goes through another perigee close to where the first perigee had taken place.

text: The gravitational force between the Sun and moon induces the precession in Earth's orbit, which is the major cause of the climate oscillation of Earth that has a period of 19,000 to 23,000 years. It follows that changes in Earth's orbital parameters (e.g., orbital inclination, the angle between Earth's rotation axis and its plane of orbit) is important to the study of Earth's climate, in particular to the study of past ice ages. (See also nodal precession. For precession of the lunar orbit see lunar precession).

text: The gravitational force between the Sun and moon induces the precession in Earth's orbit, which is the major cause of the climate oscillation of Earth that has a period of 19,000 to 23,000 years. It follows that changes in Earth's orbital parameters (e.g., orbital inclination, the angle between Earth's rotation axis and its plane of orbit) is important to the study of Earth's climate, in particular to the study of past ice ages. (See also

text: nodal precession

text: . For precession of the lunar orbit see

text: lunar precession

text: Earth's Moon probably formed out of material splashed into orbit by the impact of a large body into the early Earth. Differentiation on Earth had probably already separated many lighter materials toward the surface, so that the impact removed a disproportionate amount of silicate material from Earth, and left the majority of the dense metal behind. The Moon's density is substantially less than that of Earth, due to its lack of a large iron core.

text: Earth

text: 's

text: Moon

text: probably formed out of material splashed into orbit by the impact of a large body into the early Earth. Differentiation on Earth had probably already separated many lighter materials toward the surface, so that the impact removed a disproportionate amount of silicate material from Earth, and left the majority of the dense metal behind. The Moon's density is substantially less than that of Earth, due to its lack of a large iron core.

text: Much of the evidence on lunar calendars are from the Paleolithic period and characterized by the development of venus or feminine figurines. These "exact lunar tallies [that] fall within...a complex storied tradition involving at the center a female creatrix figure and all of her characteristic symbols," according to the anthropologist, Alexander Marshack. Feminine figures, such as Venus of Willendorf and Venus of Laussel, bear traces of having been covered in red ochre.

text: Much of the evidence on lunar calendars are from the

text: Paleolithic period

text: and characterized by the development of venus or feminine figurines. These "exact lunar tallies [that] fall within...a complex storied tradition involving at the center a female creatrix figure and all of her characteristic symbols," according to the anthropologist, Alexander Marshack. Feminine figures, such as

text: Venus of Willendorf

text: and

text: Venus of Laussel

text: , bear traces of having been covered in red ochre.

text: Planté is a lunar crater that is situated near the eastern inner wall of the much larger crater Keeler. Just to the east, attached to the exterior of Keeler, is the large crater Heaviside. Planté is located on the far side of the Moon and cannot be viewed directly from the Earth.

text: Planté is a

text: lunar crater

text: that is situated near the eastern inner wall of the much larger crater

text: Keeler

text: . Just to the east, attached to the exterior of Keeler, is the large crater

text: Heaviside

text: . Planté is located on the

text: far side

text: of the

text: Moon

text: and cannot be viewed directly from the

text: Earth

text: The contrasting elements of the blood described in line 3 and the "purity" of the unclouded moon in line 30 represents a major theme of the work. The moon's surface appears unchanging and contrasts with the earth that has been stained with the blood of men as the result of "arrogant power". As the poem speaks of the pristine nature of the moon's surface in the third stanza Helen Vendler suggests that it broadens the contrast between the two surfaces to highlight the difference between "the mortal and the incorruptible". However, she also states that the poem's theme of life and death shifts focus in the final stanza as the poet discusses the trapped butterflies, which "brings into view the pathos of life, rather than its violence".

text: The contrasting elements of the blood described in line 3 and the "purity" of the unclouded moon in line 30 represents a major theme of the work. The moon's surface appears unchanging and contrasts with the earth that has been stained with the blood of men as the result of "arrogant power". As the poem speaks of the pristine nature of the moon's surface in the third stanza

text: Helen Vendler

text: suggests that it broadens the contrast between the two surfaces to highlight the difference between "the mortal and the incorruptible". However, she also states that the poem's theme of life and death shifts focus in the final stanza as the poet discusses the trapped butterflies, which "brings into view the pathos of life, rather than its violence".

text: In 1959 the Soviets obtained the first images of the far side of the Moon, never previously visible to humans. The U.S. exploration of the Moon began with the Ranger 4 impactor in 1962. Starting in 1966 the Soviets successfully deployed a number of landers to the Moon which were able to obtain data directly from the Moon's surface; just four months later, Surveyor 1 marked the debut of a successful series of U.S. landers. The Soviet unmanned missions culminated in the Lunokhod program in the early 1970s, which included the first unmanned rovers and also successfully brought lunar soil samples to Earth for study. This marked the first (and to date the only) automated return of extraterrestrial soil samples to Earth. Unmanned exploration of the Moon continues with various nations periodically deploying lunar orbiters, and in 2008 the Indian Moon Impact Probe.

text: In 1959 the Soviets obtained the first images of the

text: far side of the Moon

text: , never previously visible to humans. The U.S. exploration of the Moon began with the

text: Ranger 4

text: impactor in 1962. Starting in 1966 the Soviets successfully deployed a number of

text: landers

text: to the Moon which were able to obtain data directly from the Moon's surface; just four months later,

text: Surveyor 1

text: marked the debut of a successful series of U.S. landers. The Soviet unmanned missions culminated in the

text: Lunokhod program

text: in the early 1970s, which included the first unmanned rovers and also successfully

text: brought lunar soil samples to Earth

text: for study. This marked the first (and to date the only) automated return of extraterrestrial soil samples to Earth. Unmanned exploration of the Moon continues with various nations periodically deploying lunar orbiters, and in 2008 the Indian

text: Moon Impact Probe

text: Nobile is a lunar crater that is located near the southern pole of the Moon. It lies to the south of the crater Scott, along the western rim of Amundsen. Between Nobile and the southern pole lie the smaller craters Shoemaker and Faustini.

text: Nobile is a

text: lunar

text: crater

text: that is located near the

text: southern pole

text: of the

text: Moon

text: . It lies to the south of the crater

text: Scott

text: , along the western rim of

text: Amundsen

text: . Between Nobile and the

text: southern pole

text: lie the smaller craters

text: Shoemaker

text: and

text: Faustini

text: Smooth plains are widespread flat areas resembling the lunar maria of the Moon, which fill depressions of various sizes. A prime example of a smooth plain is the one in which fills a wide ring surrounding the Caloris Basin, the largest impact basin on Mercury. However, a noticeable difference between the lunar maria of the Moon and the smooth plains of Mercury is that these smooth plains have the same albedo, or properties, as the bordering inter-crater plains. Even with a lack of volcanic features, it is still believed that smooth plains are of volcanic origin.

text: Smooth plains are widespread flat areas resembling the

text: lunar maria

text: of the Moon, which fill depressions of various sizes. A prime example of a smooth plain is the one in which fills a wide ring surrounding the

text: Caloris Basin

text: , the largest impact basin on Mercury. However, a noticeable difference between the lunar maria of the Moon and the smooth plains of Mercury is that these smooth plains have the same

text: albedo

text: , or properties, as the bordering inter-crater plains. Even with a lack of volcanic features, it is still believed that smooth plains are of volcanic origin.

text: The Earth's shadow or umbra is as curved as the planet Earth is, and it extends 1.4 million kilometers into space (the antumbra, however, extends indefinitely). When the Sun, the Earth and the Moon are aligned perfectly (or almost perfectly), with the Earth in between the Sun and the Moon, the Earth's shadow falls onto the surface of the Moon which is facing the night side of the Earth, such that observers see the shadow gradually turn the bright full Moon dark, and then light again, creating a lunar eclipse.

text: The Earth's shadow or

text: umbra

text: is as curved as the planet Earth is, and it extends 1.4 million kilometers into space (the

text: antumbra

text: , however, extends indefinitely). When the

text: Sun

text: , the Earth and the

text: Moon

text: are aligned perfectly (or almost perfectly), with the Earth in between the Sun and the Moon, the Earth's shadow falls onto the surface of the Moon which is facing the night side of the Earth, such that observers see the shadow gradually turn the bright full Moon dark, and then light again, creating a

text: lunar eclipse

text: The central peaks of large lunar craters may contain material that rose from as far 19 kilometers beneath the surface when the peaks formed by rebound of the compressed rock under the crater. Material moved from the interior of craters is piled in their rims. These and other processes make possibly novel concentrations of minerals accessible to future prospectors from lunar colonies.

text: Donna is a tiny lunar crater on the near side of the Moon. It is located in the eastern half of the Mare Tranquillitatis, at the summit of the lunar dome Omega (ω) Cauchy. As such domes are thought to be volcanic in nature, it appears likely that this crater was created by an eruption. This is in contrast to most lunar craters, which are now believed to be created by impacts. This crater is sufficiently small that it requires a large telescope to resolve.

text: Donna is a tiny

text: lunar

text: crater

text: on the near side of the

text: Moon

text: . It is located in the eastern half of the

text: Mare Tranquillitatis

text: , at the summit of the

text: lunar dome

text: Omega (ω) Cauchy. As such domes are thought to be volcanic in nature, it appears likely that this crater was created by an eruption. This is in contrast to most lunar craters, which are now believed to be created by impacts. This crater is sufficiently small that it requires a large

text: telescope

text: to resolve.

text: Earth has one Moon, the largest moon of any rocky planet in the Solar System. Earth also has at least two co-orbitals: the asteroids 3753 Cruithne and 2002 AA; however, since they do not orbit Earth, they are not considered moons. (See Other moons of Earth and Quasi-satellite.)

text: Earth

text: has one

text: Moon

text: , the largest moon of any rocky planet in the Solar System. Earth also has at least two

text: co-orbital

text: s: the

text: asteroid

text: s

text: 3753 Cruithne

text: and

text: 2002 AA

text: ; however, since they do not orbit Earth, they are not considered moons. (See

text: Other moons of Earth

text: and

text: Quasi-satellite

text: This irregular area contains a number of smaller depressions that have become covered in flows of basaltic lavas. These form what are essentially miniature lunar maria. They are clustered near the southern borders of the area, and fill much of the terrain between Mare Vaporum and the Montes Haemus. These mare-like features are generally irregular in shape, and many are joined together through gaps between the more rugged islands of continental terrain.

text: This irregular area contains a number of smaller depressions that have become covered in flows of

text: basalt

text: ic

text: lava

text: s. These form what are essentially miniature lunar maria. They are clustered near the southern borders of the area, and fill much of the terrain between Mare Vaporum and the Montes Haemus. These mare-like features are generally irregular in shape, and many are joined together through gaps between the more rugged islands of continental terrain.

text: During new and  full moons, when the river is relatively less deep and the ocean tide is high, water flows in from the Atlantic, rather than the other way around. As river and ocean collide, the Amazon’s flow reverses and a water bulge speeds upstream with incredible force, forming a tidal bore with rumbling noise. The tidal phenomenon is best observed on biannual equinoxes in September and March. On an equinox, when the Moon and Sun fall into alignment with the Earth, their gravitational pull is combined, bringing the Pororoca to its peak.

text: During

text: new

text: and

text: full moons

text: , when the river is relatively less deep and the ocean tide is high, water flows in from the Atlantic, rather than the other way around. As river and ocean collide, the Amazon’s flow reverses and a water bulge speeds upstream with incredible force, forming a

text: tidal bore

text: with rumbling noise. The tidal phenomenon is best observed on

text: biannual equinoxes

text: in September and March. On an equinox, when the Moon and Sun fall into alignment with the Earth, their

text: gravitational pull

text: is combined, bringing the Pororoca to its peak.

text: Significant barriers to more universal acceptance of this technology differ in their extent for different parts of the world but generally include: lack of awareness, a limited supply of prefabricated UDDT components and a lack of interest in financing any sanitation services for the non-sewered portions of urban settlements. Existing, affordable piped water supply and sanitary sewer infrastructure may also be an impediment to widespread adoption of UDDTs as their existence not only removes two of the main drivers for UDDTs but also represents a significant public investment. This can restrict efforts to switch to new toilet types and sanitation systems.

text: Significant barriers to more universal acceptance of this technology differ in their extent for different parts of the world but generally include: lack of awareness, a limited supply of prefabricated UDDT components and a lack of interest in financing any sanitation services for the non-sewered portions of urban settlements. Existing, affordable piped

text: water supply

text: and

text: sanitary sewer

text: infrastructure may also be an impediment to widespread adoption of UDDTs as their existence not only removes two of the main drivers for UDDTs but also represents a significant public investment. This can restrict efforts to switch to new toilet types and

text: sanitation

text: systems.

text: The Lunar far side lacks direct communication with Earth, though a communication satellite at the  Lagrangian point, or a network of orbiting satellites, could enable communication between the far side of the Moon and Earth. The far side is also a good location for a large radio telescope because it is well shielded from the Earth. Due to the lack of atmosphere, the location is also suitable for an array of optical telescopes, similar to the Very Large Telescope in Chile. To date, there has been no ground exploration of the far side.

text: The

text: Lunar far side

text: lacks direct communication with Earth, though a

text: communication satellite

text: at the

text: Lagrangian point

text: , or a network of orbiting satellites, could enable communication between the far side of the Moon and Earth. The far side is also a good location for a large radio telescope because it is well shielded from the Earth. Due to the lack of atmosphere, the location is also suitable for an array of

text: optical telescope

text: s, similar to the

text: Very Large Telescope

text: in

text: Chile

text: . To date, there has been no ground exploration of the far side.

text: A partial solar eclipse occurred on July 21, 1906. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on July 21, 1906. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Bečvář () is a lunar crater that is located near the equator on the far side of the Moon from the Earth. It lies to the northeast of the crater Necho, within that feature's ray system. To the north-northeast is the crater Gregory.

text: Bečvář () is a

text: lunar

text: crater

text: that is located near the equator on the

text: far side

text: of the

text: Moon

text: from the

text: Earth

text: Necho

text: , within that feature's

text: ray system

text: . To the north-northeast is the crater

text: Gregory

text: Luna 16 was the first robotic probe to land on the Moon and safely return a sample of lunar soil back to Earth. It represented the first lunar sample return mission by the Soviet Union, and was the third lunar sample return mission overall, following the Apollo 11 and Apollo 12 missions. This mission was later successfully repeated by Luna 20 (1972) and Luna 24 (1976).

text: Luna 16

text: was the first

text: robotic probe

text: to land on the

text: Moon

text: and safely return a sample of lunar soil back to Earth. It represented the first

text: lunar sample

text: return mission by the

text: Soviet Union

text: , and was the third lunar

text: sample return mission

text: overall, following the

text: Apollo 11

text: and

text: Apollo 12

text: missions. This mission was later successfully repeated by

text: Luna 20

text: (1972) and

text: Luna 24

text: J. Herschel is large lunar crater of the variety termed a walled plain. It is located in the northern part of the Moon's surface, and so appears foreshortened when viewed from the Earth. The southeastern rim of J. Herschel forms part of the edge of the Mare Frigoris lunar mare. To the northwest is the crater Anaximander. Bordering the northern rim is a large, unnamed lunar plain. Just to the south is the small crater Horrebow.

text: J. Herschel is large

text: lunar

text: crater

text: of the variety termed a walled plain. It is located in the northern part of the

text: Moon

text: 's surface, and so appears foreshortened when viewed from the

text: Earth

text: . The southeastern rim of J. Herschel forms part of the edge of the

text: Mare Frigoris

text: lunar mare

text: . To the northwest is the crater

text: Anaximander

text: . Bordering the northern rim is a large, unnamed lunar plain. Just to the south is the small crater

text: Horrebow

text: During a total solar eclipse, the Moon's shadow covers only a small fraction of the Earth. The Earth continues to receive at least 92 percent of the amount of sunlight it receives without an eclipse – more if the penumbra of the Moon's shadow partly misses the Earth. Seen from the Moon, the Earth during a total solar eclipse is mostly brilliantly illuminated, with only a small dark patch showing the Moon's shadow. The brilliantly-lit Earth reflects a lot of light to the Moon. If the corona of the eclipsed Sun were not present, the Moon, illuminated by earthlight, would be easily visible from Earth. This would be essentially the same as the earthshine which can frequently be seen when the Moon's phase is a narrow crescent. In reality, the corona, though much less brilliant than the Sun's photosphere, is much brighter than the Moon illuminated by earthlight. Therefore, by contrast, the Moon during a total solar eclipse appears to be black, with the corona surrounding it.

text: During a total solar eclipse, the Moon's shadow covers only a small fraction of the Earth. The Earth continues to receive at least 92 percent of the amount of sunlight it receives without an eclipse – more if the

text: penumbra

text: of the Moon's shadow partly misses the Earth. Seen from the Moon, the Earth during a total solar eclipse is mostly brilliantly illuminated, with only a small dark patch showing the Moon's shadow. The brilliantly-lit Earth reflects a lot of light to the Moon. If the

text: corona

text: of the eclipsed Sun were not present, the Moon, illuminated by earthlight, would be easily visible from Earth. This would be essentially the same as the

text: earthshine

text: which can frequently be seen when the Moon's

text: phase

text: is a narrow crescent. In reality, the corona, though much less brilliant than the Sun's

text: photosphere

text: , is much brighter than the Moon illuminated by earthlight. Therefore, by contrast, the Moon during a total solar eclipse appears to be black, with the corona surrounding it.

text: Doppler tracking of the five orbiters allowed mapping of the gravitational field of the moon and discovery of mass concentrations (mascons), or gravitational highs, which were located in the centers of some (but not all) of the lunar maria.

text: Doppler tracking of the five orbiters allowed mapping of the gravitational field of the moon and discovery of

text: mass concentrations

text: (mascons), or gravitational highs, which were located in the centers of some (but not all) of the lunar maria.

text: Gioia is a lunar crater that is located in the vicinity of the north pole of the Moon. It is named after the Italian inventor Flavio Gioia. As it lies so close to the northern limb, it is viewed nearly from the edge making difficult to observe from the Earth. The crater is attached to the southern rim of the larger Byrd, a formation with low walls. To the south-southeast is the crater Main.

text: Gioia is a

text: lunar

text: crater

text: that is located in the vicinity of the north pole of the

text: Moon

text: . It is named after the Italian inventor

text: Flavio Gioia

text: . As it lies so close to the northern limb, it is viewed nearly from the edge making difficult to observe from the

text: Earth

text: . The crater is attached to the southern rim of the larger

text: Byrd

text: , a formation with low walls. To the south-southeast is the crater

text: Main

text: The Exploration Systems Architecture Study that followed the Vision for Space Exploration of 2004 recommended the development of a new class of vehicles that have similar capabilities to their Apollo predecessors with several key differences.  In part to retain some of the Space Shuttle program workforce and ground infrastructure, the launch vehicles were to use Shuttle-derived technologies.  Secondly, rather than launching the crew and cargo on the same rocket, the smaller Ares I was to launch the crew with the larger Ares V to handle the heavier cargo.  The two payloads were to rendezvous in low Earth orbit and then head to the Moon from there.   The Apollo Lunar Module could not carry enough fuel to reach the polar regions of the Moon but the Altair lunar lander was intended to access any part of the Moon.  While the Altair and surface systems would have been equally necessary for Project Constellation to reach fruition, the focus was on developing the Orion spacecraft to shorten the gap in US access to orbit following the retirement of the Space Shuttle in 2010.

text: The

text: Exploration Systems Architecture Study

text: that followed the

text: Vision for Space Exploration

text: of 2004 recommended the development of a new class of vehicles that have similar capabilities to their Apollo predecessors with several key differences.  In part to retain some of the Space Shuttle program workforce and ground infrastructure, the launch vehicles were to use

text: Shuttle-derived

text: technologies.  Secondly, rather than launching the crew and cargo on the same rocket, the smaller

text: Ares I

text: was to launch the crew with the larger

text: Ares V

text: to handle the heavier cargo.  The two payloads were to

text: rendezvous in low Earth orbit

text: and then head to the Moon from there.   The Apollo Lunar Module could not carry enough fuel to reach the polar regions of the Moon but the

text: Altair lunar lander

text: was intended to access any part of the Moon.  While the Altair and surface systems would have been equally necessary for

text: Project Constellation

text: to reach fruition, the focus was on developing the

text: Orion spacecraft

text: to shorten the gap in US access to orbit following the retirement of the Space Shuttle in 2010.

text: Hygiene in ancient Rome was not ideal for combatting diseases. Their sewer system, praised for its longevity, had many flaws. As Water History’s Roger Hanson explains, street drainage and sewage flowed through the same pipes, which led to sewage openings on the streets. Also, since most sewer systems were privately owned, they were also privately maintained and in turn neglected. Instead, citizens would turn to their latrines; if they lived on anything but the ground floor they would even throw their excrement onto the street. This led to exposure of sewage to flies, dogs, and bacteria, all of which helped spread disease among Romans.

text: Hygiene in ancient Rome was not ideal for combatting diseases. Their

text: sewer system

text: , praised for its longevity, had many flaws. As Water History’s Roger Hanson explains, street drainage and sewage flowed through the same pipes, which led to sewage openings on the streets. Also, since most sewer systems were privately owned, they were also privately maintained and in turn neglected. Instead, citizens would turn to their latrines; if they lived on anything but the ground floor they would even throw their excrement onto the street. This led to exposure of sewage to flies, dogs, and bacteria, all of which helped spread disease among Romans.

text: Ellison is a lunar impact crater that lies on the far side of the Moon from the Earth. It is located just beyond the northwest limb of the Moon, to the southwest of the large walled plain Poczobutt. Due west of Ellison is the crater Coulomb.

text: Ellison is a

text: lunar

text: impact crater

text: that lies on the

text: far side

text: of the

text: Moon

text: from the

text: Earth

text: . It is located just beyond the northwest limb of the Moon, to the southwest of the large walled plain

text: Poczobutt

text: . Due west of Ellison is the crater

text: Coulomb

text: (2014-2015) Resolved: the United States Federal Government should increase its development of the Earth's moon in one or more of the following areas: energy, minerals, and/or water.

text: Due to the landing site restrictions that resulted from constraining the launch to a free return that flew by the Moon, subsequent Apollo missions, starting with Apollo 12 and including the ill-fated Apollo 13, used a hybrid trajectory that launched to a highly elliptical Earth orbit that fell short of the Moon with effectively a free return to the atmospheric entry corridor. They then performed a mid-course maneuver to change to a trans-Lunar trajectory that was not a free return. This retained the safety characteristics of being on a free return upon launch, and only departed from free return once the systems were checked out and the lunar module was docked with the command module, providing back-up maneuver capabilities.  In fact, within hours after the accident, Apollo 13 used the lunar module to maneuver from its planned trajectory to a free-return trajectory. Apollo 13 was the only Apollo mission to actually turn around the Moon in a free-return trajectory (however, two hours after perilune, propulsion was applied to speed the return to Earth by 10 hours and move the landing spot from the Indian Ocean to the Pacific Ocean).

text: Due to the landing site restrictions that resulted from constraining the launch to a free return that flew by the Moon, subsequent Apollo missions, starting with

text: Apollo 12

text: and including the ill-fated

text: Apollo 13

text: , used a hybrid trajectory that launched to a highly elliptical Earth orbit that fell short of the Moon with effectively a free return to the atmospheric entry corridor. They then performed a mid-course maneuver to change to a trans-Lunar trajectory that was not a free return. This retained the safety characteristics of being on a free return upon launch, and only departed from free return once the systems were checked out and the lunar module was docked with the command module, providing back-up maneuver capabilities.  In fact, within hours after the accident, Apollo 13 used the lunar module to maneuver from its planned trajectory to a free-return trajectory. Apollo 13 was the only Apollo mission to actually turn around the Moon in a free-return trajectory (however, two hours after perilune, propulsion was applied to speed the return to Earth by 10 hours and move the landing spot from the Indian Ocean to the Pacific Ocean).

text: Graha (from Sanskrit ग्रह gráha—seizing, laying hold of, holding) is a 'cosmic influencer' on the living beings of mother Bhumidevi (Earth). In Hindu astrology, the Navagraha (Sanskrit: नवग्रह, nine seizers or nine influencers) are some of these major influencers.  All the navagraha have relative movement with respect to the background of fixed stars in the zodiac. This includes the planets:  Mars, Mercury, Jupiter, Venus, and Saturn, the Sun, the Moon, as well as positions in the sky, Rahu (north or ascending lunar node) and Ketu (south or descending lunar node).

text: Graha (from Sanskrit ग्रह gráha—seizing, laying hold of, holding) is a 'cosmic influencer' on the living beings of mother

text: Bhumidevi

text: (Earth). In

text: Hindu astrology

text: , the

text: Navagraha

text: (Sanskrit: नवग्रह, nine seizers or nine influencers) are some of these major influencers.  All the navagraha have relative movement with respect to the background of fixed stars in the

text: zodiac

text: . This includes the planets:

text: Mars

text: Mercury

text: Jupiter

text: Venus

text: , and

text: Saturn

text: , the

text: Sun

text: , the

text: Moon

text: , as well as positions in the sky,

text: Rahu

text: (north or ascending

text: lunar node

text: ) and

text: Ketu

text: (south or descending lunar node).

text: This experiment used radar to study the Moon's surface and interior. Radar waves with wavelengths between 2 and 60 meters (frequencies of 5, 15, and 150 MHz) were transmitted through a series of antennas near the back of the Apollo Service Module. After the waves were reflected by the Moon, they were received using the same antennas and the data was recorded on film for analysis on Earth. The primary purpose of this experiment was to "see" into the upper 2 kilometers of the Moon's crust in a manner somewhat analogous to using seismic waves to study the internal structure of the Moon. This was possible because very long radar wavelengths were used and because the Moon is very dry, which allowed the radar waves to penetrate much deeper into the Moon than would have been possible if water were present in lunar rocks. (A radar experiment on the space shuttle has been similarly used to map ancient river valleys beneath the Sahara Desert.) This experiment also provided very precise information about the Moon's topography. In addition to studying the Moon, the experiment also measured radio emissions from the Milky Way Galaxy.

text: This experiment used radar to study the

text: Moon

text: 's surface and interior.

text: Radar

text: waves with wavelengths between 2 and 60 meters (frequencies of 5, 15, and 150 MHz) were transmitted through a series of

text: antennas

text: near the back of the

text: Apollo Service Module

text: . After the waves were reflected by the

text: Moon

text: , they were received using the same antennas and the data was recorded on film for analysis on Earth. The primary purpose of this experiment was to "see" into the upper 2 kilometers of the Moon's crust in a manner somewhat analogous to using seismic waves to study the internal structure of the

text: Moon

text: . This was possible because very long radar wavelengths were used and because the Moon is very dry, which allowed the radar waves to penetrate much deeper into the Moon than would have been possible if water were present in lunar rocks. (A radar experiment on the

text: space shuttle

text: has been similarly used to map ancient river valleys beneath the

text: Sahara

text: Desert.) This experiment also provided very precise information about the Moon's topography. In addition to studying the Moon, the experiment also measured radio emissions from the

text: Milky Way

text: Galaxy

text: Considering the Earth–Moon system as a binary planet, its centre of gravity is within Earth, about  or 72.6% of the Earth's radius from the centre of the Earth. This centre of gravity remains on the line between the centres of the earth and Moon as the Earth completes its diurnal rotation. The path of the Earth–Moon system in its solar orbit is defined as the movement of this mutual centre of gravity around the sun. Consequently, Earth's centre veers inside and outside the solar orbital path during each synodic month as the Moon moves in its orbit around the common centre of gravity.

text: Considering the Earth–Moon system as a

text: binary planet

text: , its centre of gravity is within Earth, about  or 72.6% of the Earth's radius from the centre of the Earth. This centre of gravity remains on the line between the centres of the earth and Moon as the Earth completes its diurnal rotation. The path of the Earth–Moon system in its solar orbit is defined as the movement of this mutual centre of gravity around the sun. Consequently, Earth's centre veers inside and outside the solar orbital path during each synodic month as the Moon moves in its orbit around the common centre of gravity.

text: In Lofting's original books, the Giant Moth makes the arduous trip between the earth and the moon in Doctor Dolittle's Garden and Doctor Dolittle in the Moon.

text: Wiesner was portrayed by Al Franken in the 1998 HBO miniseries From the Earth to the Moon.

text: Wiesner was portrayed by

text: Al Franken

text: in the 1998

text: HBO

text: miniseries

text: From the Earth to the Moon

text: Due to the low viscosity of most lunar lava, volcanic mountains were seldom created. Instead, basaltic lava flooded large areas, which became lunar maria. Shield volcanoes are known from a few areas on the Moon; they are called lunar domes. Some areas of the Moon are covered with a usually dark coating, which is interpreted as pyroclastic deposits. Sometimes they form a dark halo around rilles. See also:

text: Due to the low viscosity of most lunar

text: lava

text: , volcanic mountains were seldom created. Instead, basaltic lava flooded large areas, which became

text: lunar maria

text: Shield volcano

text: es are known from a few areas on the Moon; they are called

text: lunar dome

text: s. Some areas of the Moon are covered with a usually dark coating, which is interpreted as

text: pyroclastic deposits

text: . Sometimes they form a dark halo around

text: rille

text: s. See also:

text: Solar and lunar eclipses were scientifically explained by Aryabhata. He states that the Moon and planets shine by reflected sunlight. Instead of the prevailing cosmogony in which eclipses were caused by Rahu and Ketu (identified as the pseudo-planetary lunar nodes), he explains eclipses in terms of shadows cast by and falling on Earth. Thus, the lunar eclipse occurs when the moon enters into the Earth's shadow (verse gola.37). He discusses at length the size and extent of the Earth's shadow (verses gola.38–48) and then provides the computation and the size of the eclipsed part during an eclipse. Later Indian astronomers improved on the calculations, but Aryabhata's methods provided the core. His computational paradigm was so accurate that 18th-century scientist Guillaume Le Gentil, during a visit to Pondicherry, India, found the Indian computations of the duration of the lunar eclipse of 30 August 1765 to be short by 41 seconds, whereas his charts (by Tobias Mayer, 1752) were long by 68 seconds.

text: Solar and lunar eclipses were scientifically explained by Aryabhata. He states that the

text: Moon

text: and planets shine by reflected sunlight. Instead of the prevailing cosmogony in which eclipses were caused by

text: Rahu

text: and

text: Ketu

text: (identified as the pseudo-planetary

text: lunar nodes

text: ), he explains eclipses in terms of shadows cast by and falling on Earth. Thus, the lunar eclipse occurs when the moon enters into the Earth's shadow (verse gola.37). He discusses at length the size and extent of the Earth's shadow (verses gola.38–48) and then provides the computation and the size of the eclipsed part during an eclipse. Later Indian astronomers improved on the calculations, but Aryabhata's methods provided the core. His computational paradigm was so accurate that 18th-century scientist

text: Guillaume Le Gentil

text: , during a visit to Pondicherry, India, found the Indian computations of the duration of the

text: lunar eclipse

text: of 30 August 1765 to be short by 41 seconds, whereas his charts (by Tobias Mayer, 1752) were long by 68 seconds.

text: There has been historical controversy over whether features on the Moon's surface change over time. Today, many of these claims are thought to be illusory, resulting from observation under different lighting conditions, poor astronomical seeing, or inadequate drawings. However, outgassing does occasionally occur, and could be responsible for a minor percentage of the reported lunar transient phenomena. Recently, it has been suggested that a roughly  diameter region of the lunar surface was modified by a gas release event about a million years ago. The Moon's appearance, like that of the Sun, can be affected by Earth's atmosphere: common effects are a 22° halo ring formed when the Moon's light is refracted through the ice crystals of high cirrostratus cloud, and smaller coronal rings when the Moon is seen through thin clouds.

text: There has been historical controversy over whether features on the Moon's surface change over time. Today, many of these claims are thought to be illusory, resulting from observation under different lighting conditions, poor

text: astronomical seeing

text: , or inadequate drawings. However,

text: outgassing

text: does occasionally occur, and could be responsible for a minor percentage of the reported

text: lunar transient phenomena

text: . Recently, it has been suggested that a roughly  diameter region of the lunar surface was modified by a gas release event about a million years ago. The Moon's appearance, like that of the Sun, can be affected by Earth's atmosphere: common effects are a 22°

text: halo ring

text: formed when the Moon's light is refracted through the ice crystals of high

text: cirrostratus

text: cloud, and smaller

text: coronal rings

text: when the Moon is seen through thin clouds.

text: The nano-plague that poisoned Earth’s water supply has reached its 60-year critical mass. The Unlight enemy forced the first exodus to the moon where the outlawed banished population was supposed to die. But now the Unlights have launched from Earth and are amassing on the south-west sector of the darkside of the moon for a massive ice-mining operation.

text: Only a small portion of the Moon entered the Earth's umbral shadow, but there was a distinct darkening visible over the Moon's southern surface at greatest eclipse.

text: Elvey is a lunar crater that is located on the far side of the Moon. It is located near the northern edge of the blanket of ejecta that surrounds the Mare Orientale impact basin. To the north of Elvey is the smaller crater Nobel.

text: Elvey is a

text: lunar

text: crater

text: that is located on the

text: far side

text: of the

text: Moon

text: . It is located near the northern edge of the blanket of ejecta that surrounds the

text: Mare Orientale

text: impact basin. To the north of Elvey is the smaller crater

text: Nobel

text: There are several different periods associated with the lunar orbit. The sidereal month is the time it takes to make one complete orbit around Earth with respect to the fixed stars. It is about 27.32 days. The synodic month is the time it takes the Moon to reach the same visual phase. This varies notably throughout the year, but averages around 29.53 days. The synodic period is longer than the sidereal period because the Earth–Moon system moves in its orbit around the Sun during each sidereal month, hence a longer period is required to achieve a similar alignment of Earth, the Sun, and the Moon. The anomalistic month is the time between perigees and is about 27.55 days. The Earth–Moon separation determines the strength of the lunar tide raising force.

text: There are several different periods associated with the lunar orbit. The

text: sidereal month

text: is the time it takes to make one complete orbit around Earth with respect to the fixed stars. It is about 27.32 days. The

text: synodic month

text: is the time it takes the Moon to reach the same visual

text: phase

text: . This varies notably throughout the year, but averages around 29.53 days. The synodic period is longer than the sidereal period because the Earth–Moon system moves in its orbit around the

text: Sun

text: during each sidereal month, hence a longer period is required to achieve a similar alignment of Earth, the Sun, and the Moon. The

text: anomalistic month

text: is the time between perigees and is about 27.55 days. The Earth–Moon separation determines the strength of the lunar tide raising force.

text: Necho is a lunar impact crater on the far side of the Moon, and therefore cannot be seen directly from the Earth. It lies to the northeast of the larger crater Langemak, and about a crater diameter to the south-southwest of Bečvář.

text: Necho is a

text: lunar

text: impact crater

text: on the

text: far side

text: of the

text: Moon

text: , and therefore cannot be seen directly from the

text: Earth

text: . It lies to the northeast of the larger crater

text: Langemak

text: , and about a crater diameter to the south-southwest of

text: Bečvář

text: The lunar phase or phase of the moon is the shape of the illuminated (sunlit) portion of the Moon as seen by an observer on Earth.  The lunar phases change cyclically as the Moon orbits the Earth, according to the changing positions of the  Moon and Sun relative to the Earth. The Moon's rotation is tidally locked by the Earth's gravity, therefore the same lunar surface always faces Earth. This face is variously sunlit depending on the position of the Moon in its orbit. Therefore, the portion of this hemisphere that is visible to an observer on Earth can vary from about 100% (full moon) to 0% (new moon). The lunar terminator is the boundary between the illuminated and darkened hemispheres. Each of the four "intermediate" lunar phases (see below) is roughly seven days (~7.4 days) but this varies slightly due to the elliptical shape of the Moon's orbit. Aside from some craters near the lunar poles such as Shoemaker, all parts of the Moon see around 14.77 days of sunlight, followed by 14.77 days of "night". (The side of the Moon facing away from the Earth is sometimes called the "dark side", which is a misnomer.

text: The lunar phase or phase of the moon is the shape of the illuminated (sunlit) portion of the

text: Moon

text: as seen by an observer on

text: Earth

text: .  The lunar phases change cyclically as the Moon

text: orbit

text: s the Earth, according to the changing positions of the

text: Moon

text: and

text: Sun

text: relative to the

text: Earth

text: . The Moon's rotation is

text: tidally locked

text: by the Earth's gravity, therefore the same lunar surface always faces Earth. This face is variously sunlit depending on the position of the Moon in its orbit. Therefore, the portion of this hemisphere that is visible to an observer on Earth can vary from about 100% (

text: full moon

text: ) to 0% (

text: new moon

text: ). The

text: lunar terminator

text: is the boundary between the illuminated and darkened hemispheres. Each of the four "intermediate" lunar phases (see below) is roughly seven days (~7.4 days) but this varies slightly due to the elliptical shape of the Moon's orbit. Aside from some craters near the lunar poles such as

text: Shoemaker

text: , all parts of the Moon see around 14.77 days of sunlight, followed by 14.77 days of "night". (The side of the Moon facing away from the Earth is sometimes called the "dark side", which is a misnomer.

text: Gliese 876 b currently lies beyond the outer edge of the habitable zone but because Gliese 876 is a slowly evolving main-sequence red dwarf its habitable zone is very slowly moving outwards and will continue to do so for trillions of years. Therefore, Gliese 876 b will, in trillions of years time, lie inside Gliese 876's habitable zone, as defined by the ability of an Earth-mass planet to retain liquid water at its surface, and remain there for at least 4.6 billion years. While the prospects for life on a gas giant are unknown, large moons may be able to support a habitable environment. Models of tidal interactions between a hypothetical moon, the planet and the star suggest that large moons should be able to survive in orbit around Gliese 876 b for the lifetime of the system. On the other hand, it is unclear whether such moons could form in the first place. However, the large mass of the gas giant may make it more likely for larger moons to form.

text: Gliese 876 b currently lies beyond the outer edge of the habitable zone but because Gliese 876 is a slowly evolving main-sequence red dwarf its habitable zone is very slowly moving outwards and will continue to do so for trillions of years. Therefore, Gliese 876 b will, in trillions of years time, lie inside Gliese 876's habitable zone, as defined by the ability of an

text: Earth

text: -mass planet to retain

text: liquid

text: water at its surface, and remain there for at least 4.6 billion years. While the prospects for

text: life

text: on a gas giant are unknown, large

text: moons

text: may be able to support a

text: habitable

text: environment. Models of

text: tidal

text: interactions between a hypothetical moon, the planet and the star suggest that large moons should be able to survive in orbit around Gliese 876 b for the lifetime of the system. On the other hand, it is unclear whether such moons could form in the first place. However, the large mass of the gas giant may make it more likely for larger moons to form.

text: Because the Earth's tides are ultimately due to gravitational interaction with the Moon and Sun and the Earth's rotation, tidal power is practically inexhaustible and classified as a renewable energy resource. Movement of tides causes a loss of mechanical energy in the Earth–Moon system: this is a result of pumping of water through natural restrictions around coastlines and consequent viscous dissipation at the seabed and in turbulence. This loss of energy has caused the rotation of the Earth to slow in the 4.5 billion years since its formation. During the last 620 million years the period of rotation of the earth (length of a day) has increased from 21.9 hours to 24 hours; in this period the Earth has lost 17% of its rotational energy. While tidal power will take additional energy from the system, the effect is negligible and would only be noticed over millions of years.

text: Because the Earth's tides are ultimately due to gravitational interaction with the Moon and Sun and the Earth's rotation, tidal power is practically inexhaustible and classified as a

text: renewable energy

text: resource. Movement of tides causes a

text: loss of mechanical energy

text: in the Earth–Moon system: this is a result of pumping of water through natural restrictions around coastlines and consequent

text: viscous

text: dissipation at the

text: seabed

text: and in

text: turbulence

text: . This loss of energy has caused the rotation of the Earth to slow in the 4.5 billion years since its formation. During the last 620 million years the period of rotation of the earth (length of a day) has increased from 21.9 hours to 24 hours; in this period the Earth has lost 17% of its rotational energy. While tidal power will take additional energy from the system, the effect is negligible and would only be noticed over millions of years.

text: Because the near side is partly shielded from the solar wind by the Earth, the far side maria are expected to have the highest concentration of helium-3 on the surface of the Moon. This isotope is relatively rare on the Earth, but has good potential for use as a fuel in fusion reactors. Proponents of lunar settlement have cited the presence of this material as a reason for developing a Moon base.

text: Because the near side is partly shielded from the

text: solar wind

text: by the Earth, the far side

text: maria

text: are expected to have the highest concentration of

text: on the surface of the Moon. This

text: isotope

text: is relatively rare on the Earth, but has good potential for use as a fuel in

text: fusion

text: reactors. Proponents of lunar settlement have cited the presence of this material as a reason for developing a Moon base.

text: Zappa, Moon. Earth to Moon, RAYGUN, November 1997

text: The Moon's orbit around the Earth is elliptical, which causes the Moon to be closer to the Earth and farther away at different times.  The Moon and the Sun are aligned every two weeks, which results in spring tides – tides that are 20% higher than normal.  During the period of the new moon, the Moon and Sun are on the same side of the Earth, so the high tides or bulges produced independently by each reinforce each other (and has nothing to do with the season called spring).  Tides of maximum height and depression produced during this period are known as spring tide.  Even higher than a normal spring tide are the perigean tides. Perigean spring tides can produce unusually intense flooding along the coastal regions. Low amplitude tides are known as neap tides.

text: The Moon's orbit around the Earth is elliptical, which causes the Moon to be closer to the Earth and farther away at different times.  The Moon and the Sun are aligned every two weeks, which results in spring tides – tides that are 20% higher than normal.  During the period of the

text: new moon

text: , the Moon and Sun are on the same side of the Earth, so the high tides or bulges produced independently by each reinforce each other (and has nothing to do with the season called spring).  Tides of maximum height and depression produced during this period are known as spring tide.  Even higher than a normal spring tide are the perigean tides. Perigean spring tides can produce unusually intense flooding along the coastal regions. Low amplitude tides are known as

text: neap tide

text: s.

text: Almost all maria are on the near side of the Moon, and cover 31% of the surface of the near side, compared with 2% of the far side. This is thought to be due to a concentration of heat-producing elements under the crust on the near side, seen on geochemical maps obtained by Lunar Prospectors gamma-ray spectrometer, which would have caused the underlying mantle to heat up, partially melt, rise to the surface and erupt. Most of the Moon's mare basalts erupted during the Imbrian period, 3.0–3.5 billion years ago, although some radiometrically dated samples are as old as 4.2 billion years. Until recently, the youngest eruptions, dated by crater counting, appeared to have been only 1.2 billion years ago. In 2006, a study of Ina, a tiny depression in Lacus Felicitatis, found jagged, relatively dust-free features that, due to the lack of erosion by infalling debris, appeared to be only 2 million years old. Moonquakes and releases of gas also indicate some continued lunar activity. In 2014 NASA announced "widespread evidence of young lunar volcanism" at 70 irregular mare patches identified by the Lunar Reconnaissance Orbiter, some less than 50 million years old. This raises the possibility of a much warmer lunar mantle than previously believed, at least on the near side where the deep crust is substantially warmer due to the greater concentration of radioactive elements. Just prior to this, evidence has been presented for 2–10 million years younger basaltic volcanism inside Lowell crater, Orientale basin, located in the transition zone between the near and far sides of the Moon. An initially hotter mantle and/or local enrichment of heat-producing elements in the mantle could be responsible for prolonged activities also on the far side in the Orientale basin.

text: Almost all maria are on the near side of the Moon, and cover 31% of the surface of the near side, compared with 2% of the far side. This is thought to be due to a

text: concentration of heat-producing elements

text: under the crust on the near side, seen on geochemical maps obtained by

text: Lunar Prospector

text: s gamma-ray spectrometer, which would have caused the underlying mantle to heat up, partially melt, rise to the surface and erupt. Most of the Moon's

text: mare basalts

text: erupted during the Imbrian period, 3.0–3.5 billion years ago, although some radiometrically dated samples are as old as 4.2 billion years. Until recently, the youngest eruptions, dated by

text: crater counting

text: , appeared to have been only 1.2 billion years ago. In 2006, a study of

text: Ina

text: , a tiny depression in

text: Lacus Felicitatis

text: , found jagged, relatively dust-free features that, due to the lack of erosion by infalling debris, appeared to be only 2 million years old.

text: Moonquake

text: s and releases of gas also indicate some continued lunar activity. In 2014 NASA announced "widespread evidence of young lunar volcanism" at 70

text: irregular mare patch

text: es identified by the

text: Lunar Reconnaissance Orbiter

text: , some less than 50 million years old. This raises the possibility of a much warmer lunar mantle than previously believed, at least on the near side where the deep crust is substantially warmer due to the greater concentration of radioactive elements. Just prior to this, evidence has been presented for 2–10 million years younger basaltic volcanism inside Lowell crater, Orientale basin, located in the transition zone between the near and far sides of the Moon. An initially hotter mantle and/or local enrichment of heat-producing elements in the mantle could be responsible for prolonged activities also on the far side in the Orientale basin.

text: The Moon is the primary source of the gravitational forces that cause the tides. The proximity of the Moon to the Earth has an effect on the range of the tides at any given time. In each of its 28-day elliptical orbits, the Moon reaches a perigee, its closest point of approach to the Earth. During these periods, there is a slight increase in the average range of tides. The increases in the range of the tides is seen by a slightly higher than average high tide, as well as a slightly lower than average low tide. Additionally, twice each month, around the times of the new moon and full moon, when the Earth, Sun, and Moon are nearly in line, there is an increase in the average range of the tides. These are called "spring tides". Three or four times a year, the occurrence of a new or full moon will coincide with the perigee of the Moon, which Fergus Wood has termed the "perigean spring tides".

text: Historian Raffaele De Cesare made the following observations:

text: The partial lunar eclipse of June 26, 2010 was the first of two lunar eclipses in 2010. At maximum eclipse 53.7% of the moon was covered by the earth's shadow.

text: The partial lunar eclipse of June 26, 2010 was the first of two

text: lunar eclipse

text: s in 2010. At maximum eclipse 53.7% of the moon was covered by the earth's shadow.

text: Ritz is a lunar impact crater that is located on the far side of the Moon, just beyond the eastern limb. This portion of the lunar surface is sometimes brought into view of the Earth under favorable conditions of libration and sunlight. The crater lies to the northwest of the prominent crater Sklodowska.

text: Ritz is a

text: lunar

text: impact crater

text: that is located on the

text: far side

text: of the

text: Moon

text: , just beyond the eastern limb. This portion of the lunar surface is sometimes brought into view of the

text: Earth

text: under favorable conditions of

text: libration

text: and sunlight. The crater lies to the northwest of the prominent crater

text: Sklodowska

text: Cremona is a lunar crater that is located long the north-northwestern limb of the Moon. From the Earth this crater is viewed from the side, and the visibility is affected by libration effects. To be viewed in any detail, this crater must be seen or photographed from orbit. It is located midway between the crater Boole to the south-southeast and, on the far side of the Moon, the crater Lindblad.

text: Cremona is a

text: lunar

text: crater

text: that is located long the north-northwestern limb of the

text: Moon

text: . From the

text: Earth

text: this crater is viewed from the side, and the visibility is affected by

text: libration

text: effects. To be viewed in any detail, this crater must be seen or

text: photograph

text: ed from orbit. It is located midway between the crater

text: Boole

text: to the south-southeast and, on the

text: far side

text: of the Moon, the crater

text: Lindblad

text: Lunar materials may also be valuable for other uses.  It has also been proposed to use lunar regolith as a general construction material, through processing techniques such as sintering, hot-pressing, liquification, and the cast basalt method. Cast basalt is used on Earth for construction of, for example, pipes where a high resistance to abrasion is required. Cast basalt has a very high hardness of 8 Mohs (diamond is 10 Mohs) but is also susceptible to mechanical impact and thermal shock which could be a problem on the Moon.

text: Lunar materials may also be valuable for other uses.  It has also been proposed to use lunar regolith as a general construction material, through processing techniques such as

text: sintering

text: , hot-pressing,

text: liquification

text: , and the cast

text: basalt

text: method. Cast basalt is used on Earth for construction of, for example, pipes where a high resistance to abrasion is required. Cast basalt has a very high

text: hardness

text: of 8

text: Mohs

text: diamond

text: is 10 Mohs) but is also susceptible to mechanical impact and

text: thermal shock

text: which could be a problem on the Moon.

text: The Apollo 15 subsatellite (PFS-1) was a small satellite released into lunar orbit from the SIM bay. Its main objectives were to study the plasma, particle, and magnetic field environment of the Moon and map the lunar gravity field. Specifically, it measured plasma and energetic particle intensities and vector magnetic fields, and facilitated tracking of the satellite velocity to high precision. A basic requirement was that the satellite acquire fields and particle data everywhere on the orbit around the Moon.  The Moon's roughly circular orbit about the Earth at ~380,000 km (60 Earth radii) carried the subsatellite into both interplanetary space and various regions of the Earth's magnetosphere. The satellite orbited the Moon and returned data from August 4, 1971 until January 1973.

text: Gamma (denoted as γ) of an eclipse describes how centrally the shadow of the Moon or Earth strikes the other. The distance, when the axis of the shadow cone passes closest to Earth or Moon's center, is stated as a fraction of the equatorial radius of the Earth. The sign of gamma defines, for a solar eclipse, if the axis of the shadow passes north or south of the center of the Earth; a positive value means north. For a lunar eclipse it defines whether the axis of the Earth's shadow passes north or south of the Moon; a positive value means south. For solar eclipses the Earth is defined as that half which is exposed to the Sun (this changes with the seasons and is not related directly to the Earth's poles or equator, thus the Earth's center is wherever the Sun is directly overhead).

text: Gamma (denoted as

text: γ

text: ) of an

text: eclipse

text: describes how centrally the

text: shadow

text: of the

text: Moon

text: or

text: Earth

text: strikes the other. The distance, when the axis of the shadow cone passes closest to Earth or Moon's center, is stated as a fraction of the

text: equatorial radius

text: of the Earth. The sign of gamma defines, for a solar eclipse, if the axis of the shadow passes north or south of the center of the Earth; a positive value means north. For a lunar eclipse it defines whether the axis of the Earth's shadow passes north or south of the Moon; a positive value means south. For solar eclipses the Earth is defined as that half which is exposed to the Sun (this changes with the seasons and is not related directly to the Earth's poles or equator, thus the Earth's center is wherever the

text: Sun

text: is

text: directly overhead

text: High precision Lunar Laser Ranging (LLR) started soon after the Apollo 11 astronauts left the first retroreflector on the Moon. Additional reflectors were left by the Apollo 14 and Apollo 15 astronauts, and two French-built reflector arrays were placed on the Moon by the Soviet Luna 17 (Lunokhod 1) and Luna 21 (Lunokhod 2) lunar rover missions. Over the years since, many groups and experiments have used this technique to study the behavior of the Earth-Moon system, investigating gravitational and other effects.

text: High precision Lunar Laser Ranging (LLR) started soon after the

text: Apollo 11

text: astronauts left the first retroreflector on the Moon. Additional reflectors were left by the

text: Apollo 14

text: and

text: Apollo 15

text: astronauts, and two French-built reflector arrays were placed on the Moon by the Soviet

text: Luna 17

text: Lunokhod 1

text: ) and

text: Luna 21

text: Lunokhod 2

text: ) lunar rover missions. Over the years since, many groups and experiments have used this technique to study the behavior of the Earth-Moon system, investigating gravitational and other effects.

text: Due to its proximity and familiarity, Earth's Moon is discussed as a target for colonization. It has the benefits of proximity to Earth and lower escape velocity, allowing for easier exchange of goods and services. A drawback of the Moon is its low abundance of volatiles necessary for life such as hydrogen, nitrogen, and carbon. Water-ice deposits that exist in some polar craters could serve as a source for these elements. An alternative solution is to bring hydrogen from near-Earth asteroids and combine it with oxygen extracted from lunar rock.

text: Due to its proximity and familiarity, Earth's Moon is discussed as a target for colonization. It has the benefits of proximity to Earth and lower

text: escape velocity

text: , allowing for easier exchange of goods and services. A drawback of the Moon is its low abundance of volatiles necessary for life such as hydrogen, nitrogen, and carbon. Water-ice deposits that exist in some polar

text: craters

text: could serve as a source for these elements. An alternative solution is to bring hydrogen from near-Earth asteroids and combine it with oxygen extracted from lunar rock.

text: There were many “opticals” used in the making of Moonwalk One. The Earth rising over the moon, or the pan from the earth floating in space to the close surface of the moon, for example. There was no footage shot by the astronauts that was comparable. The “Earth Poem” sequence was composed of Hasselblad stills of the earth taken by astronauts on previous missions, and sent to an optical house to create very slow moves across the surface.

text: Using telescopes on Earth, the reflectors on the Moon, and accurate timing of laser pulses, by the early 2000s scientists could measure and predict the orbit of the Moon to an accuracy of a few centimeters. This already impressive accuracy (the Moon is typically about 385,000 km away) provides the best known test of many aspects of our theories of gravity. APOLLO improves this even further, measuring the distance between the Moon to an accuracy of a few millimeters. Using this information, scientists will be able to further test various aspects of gravity: do the Earth and the Moon react the same to gravity despite their different compositions?  Does the energy content of the Earth and the Moon react to gravity in the same way as Einstein predicts?  In general, does Einstein's General Relativity correctly predict the motion of the Moon, or are new theories required?

text: Using telescopes on Earth, the reflectors on the Moon, and accurate timing of

text: laser

text: pulses, by the early 2000s scientists could measure and predict the

text: orbit

text: of the Moon to an accuracy of a few centimeters. This already impressive accuracy (the Moon is typically about 385,000 km away) provides the best known test of many aspects of our

text: theories of gravity

text: . APOLLO improves this even further, measuring the distance between the Moon to an accuracy of a few millimeters. Using this information, scientists will be able to further test various aspects of gravity: do the Earth and the Moon react the same to gravity despite their different compositions?  Does the energy content of the Earth and the Moon react to gravity in the same way as

text: Einstein

text: predicts?  In general, does Einstein's

text: General Relativity

text: correctly predict the motion of the Moon, or are new theories required?

text: Waste water would end up primarily in the main sewers, which led into the Cloaca Maxima and finally the river Tiber. The continuous flow of water ensured that the sewers were kept clear and free of obstructions, so contributing to the hygiene of the city.

text: Waste water would end up primarily in the main sewers, which led into the

text: Cloaca Maxima

text: and finally the river

text: Tiber

text: . The continuous flow of water ensured that the sewers were kept clear and free of obstructions, so contributing to the hygiene of the city.

text: Lunar water is water that is present on the Moon. Liquid water cannot persist at the Moon's surface, and water vapor is decomposed by sunlight, with hydrogen quickly lost to outer space. However, scientists have since the 1960s conjectured that water ice could survive in cold, permanently shadowed craters at the Moon's poles. Water molecules are also detected in the thin layer of gases above the lunar surface.

text: Lunar water is water that is present on the

text: Moon

text: . Liquid water cannot persist at the Moon's surface, and

text: water vapor

text: is

text: decomposed by sunlight

text: , with

text: hydrogen

text: quickly lost to outer space. However, scientists have since the 1960s conjectured that

text: water ice

text: could survive in cold, permanently shadowed craters at the Moon's poles. Water molecules are also detected in the thin layer of gases above the lunar surface.

text: Purkyně is a lunar impact crater that lies just beyond the eastern limb of the Moon, on the far side from the Earth. When conditions of libration and sunlight allow, this crater can be viewed from the Earth, although it is seen from a very low angle and not much detail can be seen. This crater lies just to the west of the larger crater Wyld, and to the north-northwest of the even bigger Hirayama. To the west and northwest of Purkyně is the Mare Smythii.

text: Purkyně is a

text: lunar

text: impact crater

text: that lies just beyond the eastern limb of the

text: Moon

text: , on the

text: far side

text: from the

text: Earth

text: . When conditions of

text: libration

text: and sunlight allow, this crater can be viewed from the

text: Earth

text: , although it is seen from a very low angle and not much detail can be seen. This crater lies just to the west of the larger crater

text: Wyld

text: , and to the north-northwest of the even bigger

text: Hirayama

text: . To the west and northwest of Purkyně is the

text: Mare Smythii

text: The lunar crater Vetchinkin, on the far side of the moon, is named after him.

text: The lunar crater

text: Vetchinkin

text: , on the far side of the moon, is named after him.

text: Between 1972 and 1977, seismometers installed on the Moon by the Apollo missions recorded moonquakes.  The Moon was described as "ringing like a bell" during some of those quakes, specifically the shallow ones.  This phrase was brought to popular attention in March 1970, in an article in Popular Science.  When Apollo 12 deliberately crashed the Ascent Stage of its Lunar Module onto the Moon’s surface, it was claimed that the Moon rang like a bell for an hour, leading to arguments that it must be hollow like a bell.  Lunar seismology experiments since then have shown that the lunar body has shallow moonquakes that act differently from quakes on Earth, due to differences in texture, type and density of the planetary strata, but there is no evidence of any large empty space inside the body.

text: Between 1972 and 1977,

text: seismometers

text: installed on the Moon by the

text: Apollo missions

text: recorded

text: moonquakes

text: .  The Moon was described as "ringing like a bell" during some of those quakes, specifically the shallow ones.  This phrase was brought to popular attention in March 1970, in an article in

text: Popular Science

text: .  When Apollo 12 deliberately crashed the Ascent Stage of its

text: Lunar Module

text: onto the Moon’s surface, it was claimed that the Moon rang like a bell for an hour, leading to arguments that it must be hollow like a bell.  Lunar seismology experiments since then have shown that the lunar body has shallow moonquakes that act differently from quakes on Earth, due to differences in texture, type and density of the planetary strata, but there is no evidence of any large empty space inside the body.

text: Hermite is a lunar impact crater located along the northern lunar limb, close to the north pole of the Moon. It was first discovered in 1964. To the west is the crater Rozhdestvenskiy, and to the south are Lovelace and Sylvester. Grignard is located directly adjacent to the Southwest. From the Earth this crater is viewed nearly from the side, and it is illuminated by oblique sunlight.

text: Hermite is a

text: lunar

text: impact crater

text: located along the northern lunar limb, close to the north pole of the

text: Moon

text: . It was first discovered in 1964. To the west is the crater

text: Rozhdestvenskiy

text: , and to the south are

text: Lovelace

text: and

text: Sylvester

text: Grignard

text: is located directly adjacent to the Southwest. From the

text: Earth

text: this crater is viewed nearly from the side, and it is illuminated by oblique sunlight.

text: For a total solar eclipse to happen, the ratio of the apparent diameters of the Moon and of the Sun must be 1.0 or bigger and the three celestial bodies (Sun, Earth and Moon) must be aligned centrally enough. When that is the case, the Moon's disk covers the Sun's disk in the sky completely. The path of totality (i.e. of the travelling shadow of the Moon cutting off all direct sunlight from reaching the Earth's surface) is a relatively narrow strip, at most a few hundreds of kilometers across.

text: The Malta Apollo 17 lunar sample display commemorative style plaque (10 by 14 inches) consists of one "moon rock" particle specimen that was cut from lunar basalt 70017 and a Maltese flag. The basalt 70017 was collected by Apollo 17 astronaut Harrison Schmitt on the moon in 1972. Once lunar basalt 70017 was brought back to earth from the moon, the basalt moon rock was cut up into small fragments of approximately 1 gram. The specimen was encased in a plastic ball and mounted on the wooden plaque along with the Maltese flag which had been taken to the moon and back by the crew of Apollo 17. The plaque was then distributed in 1973 by President Nixon to the country of Malta, as he did that year to the other 134 countries of the world (the same countries previously for the Apollo 11 plaque display gifts) and again to all 50 states of the United States. This was done as a goodwill gesture to promote peace and harmony.

text: The Malta Apollo 17 lunar sample display commemorative style plaque (10 by 14 inches) consists of one "moon rock" particle specimen that was cut from

text: lunar basalt 70017

text: and a Maltese flag. The

text: basalt

text: Harrison Schmitt

text: on the moon in 1972. Once lunar basalt 70017 was brought back to earth from the moon, the basalt moon rock was cut up into small fragments of approximately 1 gram. The specimen was encased in a plastic ball and mounted on the wooden plaque along with the Maltese flag which had been taken to the moon and back by the crew of Apollo 17. The plaque was then distributed in 1973 by President Nixon to the country of Malta, as he did that year to the other 134 countries of the world (the same countries previously for the Apollo 11 plaque display gifts) and again to all 50 states of the United States. This was done as a goodwill gesture to promote peace and harmony.

text: Several mechanisms have been proposed for the Moon's formation 4.53 billion years ago, and some 30–50 million years after the origin of the Solar System. Recent research presented by Rick Carlson indicates a slightly lower age of between 4.40 and 4.45 billion years. These mechanisms included the fission of the Moon from Earth's crust through centrifugal force (which would require too great an initial spin of Earth), the gravitational capture of a pre-formed Moon (which would require an unfeasibly extended atmosphere of Earth to dissipate the energy of the passing Moon), and the co-formation of Earth and the Moon together in the primordial accretion disk (which does not explain the depletion of metals in the Moon). These hypotheses also cannot account for the high angular momentum of the Earth–Moon system.

text: Several mechanisms have been proposed for the Moon's formation 4.53 billion years ago, and some 30–50 million years after the origin of the Solar System. Recent research presented by Rick Carlson indicates a slightly lower age of between 4.40 and 4.45 billion years. These mechanisms included the fission of the Moon from Earth's crust through

text: centrifugal force

text: (which would require too great an initial spin of Earth), the gravitational capture of a pre-formed Moon (which would require an unfeasibly extended

text: atmosphere of Earth

text: to

text: dissipate

text: the energy of the passing Moon), and the co-formation of Earth and the Moon together in the primordial

text: accretion disk

text: (which does not explain the depletion of metals in the Moon). These hypotheses also cannot account for the high

text: angular momentum

text: of the Earth–Moon system.

text: Condorcet is a lunar crater that is located in the eastern part of the Moon's near side, to the southeast of the Mare Crisium. To the northeast of Condorcet are the craters Hansen and Alhazen.

text: Condorcet is a

text: lunar

text: crater

text: that is located in the eastern part of the

text: Moon

text: 's near side, to the southeast of the

text: Mare Crisium

text: . To the northeast of Condorcet are the craters

text: Hansen

text: and

text: Alhazen

text: The album's recording sessions took place from December 1996 to January 1997 at Studio Litho in Seattle, Washington. Studio Litho is owned by guitarist Stone Gossard. The band worked with producer Nick DiDia. The album was mixed by DiDia and Brendan O'Brien. The album featured a more polished sound compared with the band's debut album, Shame. Interiors was met with poor sales, however the band saw its cult audience expand. The lead single from Interiors, "The Day Brings", features Mike McCready from Pearl Jam on lead guitar. The album charted at number 30 on Billboards Top Heatseekers chart. Tom Moon of Rolling Stone said that "what's most notable about Interiors...is the pure pop focus of these nuanced compositions." A music video was made for the song "The Day Brings". Interiors was accompanied by a tour in the United States and Canada in 1997, as well as a small tour in Australia and New Zealand in 1998.

text: The album's recording sessions took place from December 1996 to January 1997 at Studio Litho in

text: Seattle

text: , Washington. Studio Litho is owned by guitarist

text: Stone Gossard

text: . The band worked with producer

text: Nick DiDia

text: . The album was mixed by DiDia and

text: Brendan O'Brien

text: . The album featured a more polished sound compared with the band's debut album,

text: Shame

text: . Interiors was met with poor sales, however the band saw its cult audience expand. The lead single from Interiors, "The Day Brings", features

text: Mike McCready

text: from

text: Pearl Jam

text: on lead

text: guitar

text: . The album charted at number 30 on Billboards

text: Top Heatseekers

text: chart. Tom Moon of

text: Rolling Stone

text: pop

text: focus of these nuanced compositions." A

text: music video

text: was made for the song "The Day Brings". Interiors was accompanied by a tour in the

text: United States

text: and

text: Canada

text: in 1997, as well as a small tour in

text: Australia

text: and

text: New Zealand

text: in 1998.

text: Eclipses can only occur when the Sun, Earth, and Moon are all in a straight line (termed "syzygy"). Solar eclipses occur at new moon, when the Moon is between the Sun and Earth. In contrast, lunar eclipses occur at full moon, when Earth is between the Sun and Moon. The apparent size of the Moon is roughly the same as that of the Sun, with both being viewed at close to one-half a degree wide. The Sun is much larger than the Moon but it is the precise vastly greater distance that gives it the same apparent size as the much closer and much smaller Moon from the perspective of Earth. The variations in apparent size, due to the non-circular orbits, are nearly the same as well, though occurring in different cycles. This makes possible both total (with the Moon appearing larger than the Sun) and annular (with the Moon appearing smaller than the Sun) solar eclipses. In a total eclipse, the Moon completely covers the disc of the Sun and the solar corona becomes visible to the naked eye. Because the distance between the Moon and Earth is very slowly increasing over time, the angular diameter of the Moon is decreasing. Also, as it evolves toward becoming a red giant, the size of the Sun, and its apparent diameter in the sky, are slowly increasing. The combination of these two changes means that hundreds of millions of years ago, the Moon would always completely cover the Sun on solar eclipses, and no annular eclipses were possible. Likewise, hundreds of millions of years in the future, the Moon will no longer cover the Sun completely, and total solar eclipses will not occur.

text: Eclipses can only occur when the Sun, Earth, and Moon are all in a straight line (termed "

text: syzygy

text: Solar eclipse

text: s occur at

text: new moon

text: , when the Moon is between the Sun and Earth. In contrast,

text: lunar eclipse

text: s occur at

text: full moon

text: , when Earth is between the Sun and Moon. The apparent size of the Moon is roughly the same as that of the Sun, with both being viewed at close to one-half a degree wide. The Sun is much larger than the Moon but it is the precise vastly greater distance that gives it the same apparent size as the much closer and much smaller Moon from the perspective of Earth. The variations in apparent size, due to the non-circular orbits, are nearly the same as well, though occurring in different cycles. This makes possible both

text: total

text: (with the Moon appearing larger than the Sun) and

text: annular

text: (with the Moon appearing smaller than the Sun) solar eclipses. In a total eclipse, the Moon completely covers the disc of the Sun and the solar

text: corona

text: becomes visible to the

text: naked eye

text: . Because the distance between the Moon and Earth is very slowly increasing over time, the angular diameter of the Moon is decreasing. Also, as it evolves toward becoming a

text: red giant

text: , the size of the Sun, and its apparent diameter in the sky, are slowly increasing. The combination of these two changes means that hundreds of millions of years ago, the Moon would always completely cover the Sun on solar eclipses, and no annular eclipses were possible. Likewise, hundreds of millions of years in the future, the Moon will no longer cover the Sun completely, and total solar eclipses will not occur.

text: A lunar eclipse occurs when the Moon passes within Earth's umbra (shadow). As the eclipse begins, the Earth's shadow first darkens the Moon slightly.  Then, the shadow begins to "cover" part of the Moon, turning it a dark red-brown color (typically - the color can vary based on atmospheric conditions).  The Moon appears to be reddish because of Rayleigh scattering (the same effect that causes sunsets to appear reddish) and the refraction of that light by the Earth's atmosphere into its umbra.The following simulation shows the approximate appearance of the Moon passing through the earth's shadow. The Moon's brightness is exaggerated within the umbral shadow. The southern portion of the Moon was closest to the center of the shadow, making it darkest, and most red in appearance.

text: A lunar eclipse occurs when the Moon passes within Earth's

text: umbra

text: (shadow). As the eclipse begins, the Earth's shadow first darkens the Moon slightly.  Then, the shadow begins to "cover" part of the Moon, turning it a dark red-brown color (typically - the color can vary based on atmospheric conditions).  The Moon appears to be reddish because of

text: Rayleigh scattering

text: (the same effect that causes sunsets to appear reddish) and the refraction of that light by the Earth's atmosphere into its umbra.The following simulation shows the approximate appearance of the Moon passing through the earth's shadow. The Moon's brightness is exaggerated within the umbral shadow. The southern portion of the Moon was closest to the center of the shadow, making it darkest, and most red in appearance.

text: The EPIC science team plans to upload 12 new color images per day on their website. The color balance has been adjusted to approximate an image that could be seen with the average human eye. In addition to images, scientific information will be uploaded as it becomes available after in-flight calibration is complete. The science information will be ozone and aerosol amounts, cloud reflectivity, cloud height, and vegetation information.  The EPIC instrument views the Earth from sunrise in the west to sunset in the east 12 to 13 times per day as the Earth rotates at 15 degrees of longitude per hour. Clearly visible are storms forming over the Atlantic and Pacific Oceans, major slowly moving "cloud rivers", dust aerosol plumes from Africa, the sun's reflection in the oceans, ship exhaust tracks in the clouds, rivers and lakes, and the variegated land surface patterns especially in the African deserts. The spatial resolution of the color images is about 10 km, and the resolution of the science products will be about 20 km. Once every three months, lunar images are obtained that are the same as those viewed from Earth during our full Moon. On occasion, the other side of the Moon will appear in the Earth images as the Moon crosses in front of the Earth.

text: Space travel, thus far, has been limited to our own Earth–Moon system. Also, everything that astronauts would need in the way of life support (air, water, and food) has been brought with them. This may be economical for short missions of spacecraft, but it is not the most viable solution when dealing with the life support systems of a long-term craft (such as a generation ship) or a settlement.

text: Space travel

text: , thus far, has been limited to our own

text: Earth

text: Moon

text: system. Also, everything that

text: astronauts

text: would need in the way of life support (

text: air

text: water

text: , and

text: food

text: ) has been brought with them. This may be economical for short missions of

text: spacecraft

text: , but it is not the most viable solution when dealing with the life support systems of a long-term craft (such as a

text: generation ship

text: ) or a settlement.

text: Brianchon is a lunar crater that is located along the northwestern limb of the Moon. Due to its location, from the Earth the crater is seen from the edge and its visibility is somewhat affected by libration. Thus for a more detailed view, the crater must be viewed from orbit.

text: Brianchon is a

text: lunar

text: crater

text: that is located along the northwestern limb of the

text: Moon

text: . Due to its location, from the

text: Earth

text: the crater is seen from the edge and its visibility is somewhat affected by

text: libration

text: . Thus for a more detailed view, the crater must be viewed from

text: orbit

text: The Moon's appearance is considerably more complex. Its motion, like the Sun, is between two limits — known as lunistices rather than solstices. However, its travel between lunistices is considerably faster. It takes a sidereal month to complete its cycle rather than the year-long trek of the Sun. This is further complicated as the lunistices marking the limits of the Moon's movement move on an 18.6 year cycle. For slightly over nine years the extreme limits of the moon are outside the range of sunrise. For the remaining half of the cycle the Moon never exceeds the limits of the range of sunrise. However, much lunar observation was concerned with the phase of the Moon. The cycle from one New Moon to the next runs on an entirely different cycle, the Synodic month. Thus when examining sites for lunar significance the data can appear sparse due the extremely variable nature of the moon. See Moon for more details.

text: The Moon's appearance is considerably more complex. Its motion, like the Sun, is between two limits — known as

text: lunistices

text: rather than solstices. However, its travel between lunistices is considerably faster. It takes a

text: sidereal month

text: to complete its cycle rather than the year-long trek of the Sun. This is further complicated as the lunistices marking the limits of the Moon's movement move on

text: an 18.6 year cycle

text: . For slightly over nine years the extreme limits of the moon are outside the range of sunrise. For the remaining half of the cycle the Moon never exceeds the limits of the range of sunrise. However, much lunar observation was concerned with the

text: phase

text: of the Moon. The cycle from one

text: New Moon

text: to the next runs on an entirely different cycle, the

text: Synodic month

text: . Thus when examining sites for lunar significance the data can appear sparse due the extremely variable nature of the moon. See

text: Moon

text: for more details.

text: The Moon's orbit around the Earth is an ellipse, as is the Earth's orbit around the Sun. The apparent sizes of the Sun and Moon therefore vary. The magnitude of an eclipse is the ratio of the apparent size of the Moon to the apparent size of the Sun during an eclipse. An eclipse that occurs when the Moon is near its closest distance to Earth (i.e., near its perigee) can be a total eclipse because the Moon will appear to be large enough to completely cover the Sun's bright disk or photosphere; a total eclipse has a magnitude greater than 1. Conversely, an eclipse that occurs when the Moon is near its farthest distance from Earth (i.e., near its apogee) can only be an annular eclipse because the Moon will appear to be slightly smaller than the Sun; the magnitude of an annular eclipse is less than 1. Slightly more solar eclipses are annular than total because, on average, the Moon lies too far from Earth to cover the Sun completely. A hybrid eclipse occurs when the magnitude of an eclipse changes during the event from less to greater than one, so the eclipse appears to be total at some locations on Earth and annular at other locations.

text: The Moon's orbit around the Earth is an

text: ellipse

text: , as is the Earth's orbit around the Sun. The apparent sizes of the Sun and Moon therefore vary. The

text: magnitude of an eclipse

text: is the ratio of the apparent size of the Moon to the apparent size of the Sun during an eclipse. An eclipse that occurs when the Moon is near its closest distance to Earth (i.e., near its

text: perigee

text: ) can be a total eclipse because the Moon will appear to be large enough to completely cover the Sun's bright disk or

text: photosphere

text: ; a total eclipse has a magnitude greater than 1. Conversely, an eclipse that occurs when the Moon is near its farthest distance from Earth (i.e., near its

text: apogee

text: ) can only be an annular eclipse because the Moon will appear to be slightly smaller than the Sun; the magnitude of an annular eclipse is less than 1. Slightly more solar eclipses are annular than total because, on average, the Moon lies too far from Earth to cover the Sun completely. A hybrid eclipse occurs when the magnitude of an eclipse changes during the event from less to greater than one, so the eclipse appears to be total at some locations on Earth and annular at other locations.

text: Gilbert's magnetism was the invisible force that many other natural philosophers, such as Kepler, seized upon, incorrectly, as governing the motions that they observed.  While not attributing magnetism to attraction among the stars, Gilbert pointed out the motion of the skies was due to earth's rotation, and not the rotation of the spheres, 20 years before Galileo (but 57 years after Copernicus who stated it openly in his work "De revolutionibus orbium coelestium" published in 1543 ) (see external reference below). Gilbert made the first attempt to map the surface markings on the Moon in the 1590s. His chart, made without the use of a telescope, showed outlines of dark and light patches on the moon's face. Contrary to most of his contemporaries, Gilbert believed that the light spots on the Moon were water, and the dark spots land.

text: Gilbert's

text: magnetism

text: was the invisible force that many other natural philosophers, such as

text: Kepler

text: , seized upon, incorrectly, as governing the motions that they observed.  While not attributing magnetism to attraction among the stars, Gilbert pointed out the motion of the skies was due to earth's rotation, and not the rotation of the spheres, 20 years before

text: Galileo

text: (but 57 years after

text: Copernicus

text: who stated it openly in his work "

text: De revolutionibus orbium coelestium

text: " published in 1543 ) (see external reference below). Gilbert made the first attempt to map the surface markings on the Moon in the 1590s. His chart, made without the use of a telescope, showed outlines of dark and light patches on the moon's face. Contrary to most of his contemporaries, Gilbert believed that the light spots on the Moon were water, and the dark spots land.

text: The lighter-coloured regions of the Moon are called terrae, or more commonly highlands, because they are higher than most maria. They have been radiometrically dated to having formed 4.4 billion years ago, and may represent plagioclase cumulates of the lunar magma ocean. In contrast to Earth, no major lunar mountains are believed to have formed as a result of tectonic events.

text: The lighter-coloured regions of the Moon are called terrae, or more commonly highlands, because they are higher than most maria. They have been radiometrically dated to having formed 4.4 billion years ago, and may represent

text: plagioclase

text: cumulates

text: of the

text: lunar magma ocean

text: . In contrast to Earth, no major lunar mountains are believed to have formed as a result of tectonic events.

text: The most distinctive aspect of the Moon is the contrast between its bright and dark zones. Lighter surfaces are the lunar highlands, which receive the name of terrae (singular terra, from the Latin for Earth), and the darker plains are called maria (singular mare, from the Latin for sea), after Johannes Kepler who introduced the name in the 17th century. The highlands are anorthositic in composition, whereas the maria are basaltic. The maria often coincide with the "lowlands," but it is important to note that the lowlands (such as within the South Pole-Aitken basin) are not always covered by maria. The highlands are older than the visible maria, and hence are more heavily cratered.

text: The most distinctive aspect of the Moon is the contrast between its bright and dark zones. Lighter surfaces are the lunar highlands, which receive the name of terrae (singular terra, from the

text: Latin

text: for

text: Earth

text: ), and the darker plains are called maria (singular mare, from the Latin for

text: sea

text: ), after

text: Johannes Kepler

text: who introduced the name in the 17th century. The highlands are

text: anorthositic

text: in composition, whereas the maria are

text: basalt

text: ic. The maria often coincide with the "lowlands," but it is important to note that the lowlands (such as within the

text: South Pole-Aitken basin

text: ) are not always covered by maria. The highlands are older than the visible maria, and hence are more heavily cratered.

text: A partial solar eclipse occurred on August 30, 1924. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 30, 1924. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The first spacecraft to perform a successful lunar soft landing was Luna 9 and the first uncrewed vehicle to orbit the Moon was Luna 10, both in 1966. Rock and soil samples were brought back to Earth by three Luna sample return missions (Luna 16 in 1970, Luna 20 in 1972, and Luna 24 in 1976), which returned 0.3 kg total. Two pioneering robotic rovers landed on the Moon in 1970 and 1973 as a part of Soviet Lunokhod programme.

text: The first spacecraft to perform a successful lunar

text: soft landing

text: was

text: Luna 9

text: and the first uncrewed vehicle to orbit the Moon was

text: Luna 10

text: , both in 1966.

text: Rock and soil samples

text: were brought back to Earth by three Luna

text: sample return mission

text: s (

text: Luna 16

text: in 1970,

text: Luna 20

text: in 1972, and

text: Luna 24

text: in 1976), which returned 0.3 kg total. Two pioneering robotic

text: rovers

text: landed on the Moon in 1970 and 1973 as a part of Soviet

text: Lunokhod programme

text: Former U.S. President George W. Bush, in an address about his Vision for Space Exploration, suggested that the Moon may serve as a cost-effective construction, launching and fueling site for future space exploration missions. As President Bush noted, "(Lunar) soil contains raw materials that might be harvested and processed into rocket fuel or breathable air."  For example, the proposed Ares V heavy-lift rocket system could cost-effectively deliver raw materials from Earth to a docking station, (connected to the lunar elevator as a counterweight,) where future spacecraft could be built and launched, while extracted lunar resources could be shipped up from a base on the Moon's surface, near the elevator's anchoring point. If the elevator was connected somehow to a lunar base built near the Moon's north pole, then workers could also mine the water ice which is known to exist there, providing an ample source of readily accessible water for the crew at the elevator's docking station. Also, since the total energy needed for transit between the Moon and Mars is considerably less than for between Earth and Mars, this concept could lower some of the engineering obstacles to sending humans to Mars.

text: Former

text: U.S. President

text: George W. Bush

text: , in an address about his

text: Vision for Space Exploration

text: , suggested that the Moon may serve as a cost-effective construction, launching and fueling

text: site

text: for future space exploration missions. As President Bush noted, "(Lunar) soil contains raw materials that might be harvested and processed into rocket fuel or breathable air."  For example, the proposed

text: Ares V

text: heavy-lift rocket system could cost-effectively deliver

text: raw material

text: s from Earth to a

text: docking station

text: , (connected to the lunar elevator as a counterweight,) where future spacecraft could be built and launched, while extracted lunar resources could be shipped up from a base on the Moon's surface, near the elevator's anchoring point. If the elevator was connected somehow to a lunar base built near the Moon's north pole, then workers could also mine the water ice which is known to exist there, providing an ample source of readily accessible water for the crew at the elevator's docking station. Also, since the total energy needed for transit between the Moon and Mars is considerably less than for between Earth and Mars, this concept could lower some of the engineering obstacles to sending humans to Mars.

text: A total solar eclipse will occur on January 27, 2093. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on January 27, 2093. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's

text: apparent diameter

text: is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: The proximity of the Moon in relation to Earth and Earth in relation to the Sun also has an effect on tidal ranges.  The Moon moves around Earth in an elliptic orbit that takes about 29 days to complete.  The gravitational force is greatest when the Moon is at perigee — closest to Earth — and least when it is at apogee — farthest from Earth — about two weeks after perigee.  The Moon has a larger effect on the tides than the Sun, but the Sun’s position also has an influence on the tides.  Earth moves around the Sun in an elliptic orbit that takes a little over 365 days to complete.  Its gravitational force is greatest when the Earth is at perihelion — closest to the Sun in early January — and least when the Earth is at aphelion — farthest from the Sun in early July.

text: The proximity of the Moon in relation to Earth and Earth in relation to the Sun also has an effect on tidal ranges.  The Moon moves around Earth in an elliptic orbit that takes about 29 days to complete.  The gravitational force is greatest when the Moon is at

text: perigee

text: — closest to Earth — and least when it is at

text: apogee

text: — farthest from Earth — about two weeks after perigee.  The Moon has a larger effect on the tides than the Sun, but the Sun’s position also has an influence on the tides.  Earth moves around the Sun in an

text: elliptic orbit

text: that takes a little over 365 days to complete.  Its

text: gravitational force

text: is greatest when the Earth is at perihelion — closest to the Sun in early January — and least when the Earth is at aphelion — farthest from the Sun in early July.

text: A total solar eclipse occurred on February 14, 1934. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on February 14, 1934. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: A partial solar eclipse occurred on May 9, 1967. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on May 9, 1967. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Ginzel is a lunar crater that is located on the far side of the Moon, just beyond the eastern limb. It is named after the Austrian astronomer Friedrich Karl Ginzel.  It lies at the eastern edge of the Mare Marginis, in a region of the surface that is sometimes brought into sight of the Earth due to libration. To the north-northeast of Ginzel is the crater Popov, and Dreyer lies due south.

text: Ginzel is a

text: lunar

text: crater

text: that is located on the

text: far side

text: of the

text: Moon

text: , just beyond the eastern limb. It is named after the Austrian

text: astronomer

text: Friedrich Karl Ginzel

text: .  It lies at the eastern edge of the

text: Mare Marginis

text: , in a region of the surface that is sometimes brought into sight of the

text: Earth

text: due to

text: libration

text: . To the north-northeast of Ginzel is the crater

text: Popov

text: , and

text: Dreyer

text: lies due south.

text: The only natural satellite of earth i.e.moon takes about 27.3 days to make one complete orbit around the earth. The earth orbits around the sun once every 365.2422 days (= earth’s orbital speed of 29.79 km per second). The earth and the moon in 27.3 days have moved as a system about 1/12 of the ways around the sun. This means that from one full moon to the next full moon, the moon must travel 2.2 extra days before it appears full moon. This is due to the curve of the earth’s orbit around the sun. The moon is still making one complete orbit (circle) in 27.3 days. But to line up with the earth and sun to become a full moon again it takes 29.531 days which means 354.372 days per lunar year. This makes a variance of 10.87 days a year between a lunar year and a solar year of 365.2422 days per year. To compensate this difference, the additional mass is been added after every 32.5 months on an average.

text: The only natural satellite of

text: earth

text: i.e.

text: moon

text: takes about 27.3 days to make one complete orbit around the earth. The earth orbits around the sun once every 365.2422 days (= earth’s orbital speed of 29.79 km per second). The earth and the moon in 27.3 days have moved as a system about 1/12 of the ways around the sun. This means that from one full moon to the next full moon, the moon must travel 2.2 extra days before it appears full moon. This is due to the curve of the earth’s orbit around the sun. The moon is still making one complete orbit (circle) in 27.3 days. But to line up with the earth and sun to become a full moon again it takes 29.531 days which means 354.372 days per lunar year. This makes a variance of 10.87 days a year between a lunar year and a solar year of 365.2422 days per year. To compensate this difference, the additional mass is been added after every 32.5 months on an average.

text: The heavens and the earth is a set phrase meaning "everything", i.e., the cosmos. This was made up of three levels, the habitable earth in the middle, the heavens above, an underworld below, all surrounded by a watery "ocean" of chaos as the Babylonian Tiamat. The earth itself was a flat disc, surrounded by mountains or sea. Above it was the firmament, a transparent but solid dome resting on the mountains, allowing men to see the blue of the waters above, with "windows" to allow the rain to enter, and containing the sun, moon and stars. The waters extended below the earth, which rested on pillars sunk in the waters, and in the underworld was Sheol, the abode of the dead.

text: The heavens and the earth is a

text: set phrase

text: meaning "

text: everything

text: ", i.e., the

text: cosmos

text: . This was made up of three levels, the habitable earth in the middle, the heavens above, an

text: underworld

text: below, all

text: surrounded by a watery "ocean" of chaos

text: as the Babylonian

text: Tiamat

text: . The earth itself was a flat disc, surrounded by mountains or sea. Above it was the

text: firmament

text: , a transparent but solid dome resting on the mountains, allowing men to see the blue of the waters above, with "windows" to allow the rain to enter, and containing the sun, moon and stars. The waters extended below the earth, which rested on pillars sunk in the waters, and in the underworld was

text: Sheol

text: , the abode of the dead.

text: At some unspecified date in the near future, an unknown force causes the Moon to shatter into seven pieces. As the shattered remnants of the Moon begin to collide with one another, astronomer and science popularizer "Doc" Dubois Harris calculates that the number of collisions will increase exponentially. A large number of moon fragments will begin entering Earth's atmosphere, forming a "white sky" and blanketing the earth within two years with what he calls a "Hard Rain" of bolides; this will cause the atmosphere to heat to incandescence and oceans to boil away, and make Earth uninhabitable for thousands of years. It is decided to evacuate as many people and resources as possible to a "Cloud Ark" in orbit, including a "swarm" of "arklet" habitats that will be able to avoid the debris from the moon — both to attempt to preserve the human race and to give the remaining doomed inhabitants of Earth something to hope for, to prevent civil disorder from breaking out on earth before its surface is destroyed.Each nation on Earth is invited to choose by lot a small number of young people to become eligible to join the Cloud Ark.

text: At some unspecified date in the near future, an unknown force causes the Moon to shatter into seven pieces. As the shattered remnants of the Moon begin to collide with one another, astronomer and

text: science popularizer

text: "Doc" Dubois Harris calculates that the number of collisions will increase exponentially. A large number of moon fragments will begin entering Earth's atmosphere, forming a

text: "white sky"

text: and blanketing the earth within two years with what he calls a "Hard Rain" of

text: bolide

text: s; this will cause the atmosphere to heat to incandescence and oceans to boil away, and make Earth uninhabitable for thousands of years. It is decided to evacuate as many people and resources as possible to a "Cloud Ark" in orbit, including a "swarm" of "arklet" habitats that will be able to avoid the debris from the moon — both to attempt to preserve the human race and to give the remaining doomed inhabitants of Earth something to hope for, to prevent civil disorder from breaking out on earth before its surface is destroyed.Each nation on Earth is invited to choose by lot a small number of young people to become eligible to join the Cloud Ark.

text: A total solar eclipse will occur on September 2, 2035. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on September 2, 2035. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Schorr is a lunar impact crater that lies across the eastern limb of the Moon. From the Earth this crater is viewed from the side, limiting the amount of detail that can be observed. The visibility of this crater is also affected by libration of the Moon in its orbit. The crater lies just to the northwest of the walled plain Curie, and to the east-southeast of the crater Gibbs.

text: Schorr is a

text: lunar

text: impact crater

text: that lies across the eastern limb of the

text: Moon

text: . From the

text: Earth

text: this crater is viewed from the side, limiting the amount of detail that can be observed. The visibility of this crater is also affected by

text: libration

text: of the Moon in its orbit. The crater lies just to the northwest of the walled plain

text: Curie

text: Gibbs

text: The Man in the Moon refers to any of several pareidolic images of a human face, head or body that certain traditions recognise in the disc of the full moon. The images are actually composed of the dark areas of the lunar maria, or "seas" and the lighter highlands of the lunar surface.

text: The Man in the Moon refers to any of several

text: pareidolic images

text: of a human face, head or body that certain traditions recognise in the disc of the

text: full moon

text: . The images are actually composed of the dark areas of the

text: lunar maria

text: , or "seas" and the lighter highlands of the lunar surface.

text: A total solar eclipse will occur on May 22, 2077. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on May 22, 2077. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: A solar eclipse occurs when the moon passes between the Earth and the sun, casting a shadow on Earth that temporarily obscures part or all of the sun's disc.  Eclipses can occur only when all three bodies are properly aligned.  Partial eclipses, in which only a portion of the sun's surface is obscured, are relatively common due to the width of the moon's outer shadow, or penumbra, which may be several hundred miles wide.  Total eclipses occur when the moon's inner shadow, or umbra, reaches the surface of the earth, completely obscuring the sun over a much narrower portion of the ground.  If the moon is too far away at the time of an eclipse, its umbra may not reach the Earth's surface, and only a partial eclipse will be visible.

text: A

text: solar eclipse

text: occurs when the

text: moon

text: passes between the

text: Earth

text: and the

text: sun

text: , casting a shadow on Earth that temporarily obscures part or all of the sun's disc.  Eclipses can occur only when all three bodies are properly aligned.  Partial eclipses, in which only a portion of the sun's surface is obscured, are relatively common due to the width of the moon's outer shadow, or penumbra, which may be several hundred miles wide.  Total eclipses occur when the moon's inner shadow, or umbra, reaches the surface of the earth, completely obscuring the sun over a much narrower portion of the ground.  If the moon is too far away at the time of an eclipse, its umbra may not reach the Earth's surface, and only a partial eclipse will be visible.

text: A total solar eclipse occurred on October 23, 1957. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on October 23, 1957. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: H. G. Wells is a lunar crater that is located on the far side of the Moon, behind the northeastern limb. It lies to the south of the crater Millikan, and to the northeast of Cantor. Just to the southeast is the smaller Tesla.

text: H. G. Wells is a

text: lunar

text: crater

text: that is located on the

text: far side

text: of the

text: Moon

text: , behind the northeastern limb. It lies to the south of the crater

text: Millikan

text: , and to the northeast of

text: Cantor

text: . Just to the southeast is the smaller

text: Tesla

text: The diagram (above) for stellar parallax can illustrate lunar parallax as well, if the diagram is taken to be scaled right down and slightly modified. Instead of 'near star', read 'Moon', and instead of taking the circle at the bottom of the diagram to represent the size of the Earth's orbit around the Sun, take it to be the size of the Earth's globe, and of a circle around the Earth's surface. Then, the lunar (horizontal) parallax amounts to the difference in angular position, relative to the background of distant stars, of the Moon as seen from two different viewing positions on the Earth: one of the viewing positions is the place from which the Moon can be seen directly overhead at a given moment (that is, viewed along the vertical line in the diagram); and the other viewing position is a place from which the Moon can be seen on the horizon at the same moment (that is, viewed along one of the diagonal lines, from an Earth-surface position corresponding roughly to one of the blue dots on the modified diagram).

text: Dr. Georg Waltemath was an astronomer from Hamburg, best known for his 1898 claim of a second moon of Earth as well as a system of tiny moons. It is widely held to be false.

text: Dr. Georg Waltemath was an

text: astronomer

text: from

text: Hamburg

text: , best known for his 1898 claim of a second moon of Earth as well as a system of tiny moons. It is widely held to be false.

text: This is a list of retroreflectors on the Moon. There are currently 5 different sites with reflectors. Lunar reflectors have enabled cutting edge measurements of the Earth-Moon distance for four decades.

text: This is a list of retroreflectors on the Moon. There are currently 5 different sites with

text: reflectors

text: . Lunar reflectors have enabled cutting edge measurements of the

text: Earth-Moon distance

text: for four decades.

text: The Brazil Apollo 17 lunar sample display commemorative wooden plaque (10 by 14 inches) consists of one "moon rock" particle specimen that was cut from lunar basalt 70017 and a Brazilian flag. The basalt 70017 was collected by Apollo 17 astronaut Harrison Schmitt on the moon in 1972. Once lunar basalt 70017 was brought back to earth from the moon, the basalt moon rock was cut up into small fragments of approximately 1 gram. The specimen was enveloped in a plastic ball and mounted on the wooden plaque along with the Brazilian flag which had been taken to the moon and back by the crew of Apollo 17. The wooden plaque display was then distributed in 1973 by President Richard Nixon to the country of Brazil as he did that year to all the countries of the world and all the states of the United States (the same as for the Apollo 11 plaque display gifts). This was done as a goodwill gesture to promote peace and harmony.

text: The Brazil Apollo 17 lunar sample display commemorative wooden plaque (10 by 14 inches) consists of one "moon rock" particle specimen that was cut from

text: lunar basalt 70017

text: and a

text: Brazilian flag

text: . The

text: basalt

text: Harrison Schmitt

text: on the moon in 1972. Once lunar basalt 70017 was brought back to earth from the moon, the basalt moon rock was cut up into small fragments of approximately 1 gram. The specimen was enveloped in a plastic ball and mounted on the wooden plaque along with the

text: Brazilian flag

text: which had been taken to the moon and back by the crew of Apollo 17. The wooden plaque display was then distributed in 1973 by President Richard Nixon to the country of Brazil as he did that year to all the countries of the world and all the states of the United States (the same as for the Apollo 11 plaque display gifts). This was done as a goodwill gesture to promote peace and harmony.

text: Donner is a lunar crater on the far side of the Moon. It is located just to the northeast of the Mare Australe, behind the southeastern limb of the Moon. During favorable librations this part of the lunar surface can be brought into view of the Earth, but the site is viewed from the edge and so not much detail can be seen.

text: Donner is a

text: lunar

text: crater

text: on the

text: far side

text: of the

text: Moon

text: . It is located just to the northeast of the

text: Mare Australe

text: , behind the southeastern limb of the Moon. During favorable

text: libration

text: s this part of the lunar surface can be brought into view of the

text: Earth

text: , but the site is viewed from the edge and so not much detail can be seen.

text: After one saros, the Moon will have completed roughly an integer number of lunar orbit cycles and synodic, draconic, and anomalistic periods (241, 223, 242, and 239) and the Earth-Sun-Moon geometry will be nearly identical: the Moon will have the same phase and be at the same node and the same distance from the Earth. In addition, because the saros is close to 18 years in length (about 11 days longer), the earth will be nearly the same distance from the sun, and tilted to it in nearly the same orientation (same season). Given the date of an eclipse, one saros later a nearly identical eclipse can be predicted. During this 18-year period, about 40 other solar and lunar eclipses take place, but with a somewhat different geometry. One saros equaling 18.03 years is not equal to a perfect integer number of lunar orbits (earth revolutions with respect to the fixed stars of 27.32166 days sidereal month), therefore, even though the relative geometry of the Earth-Sun-Moon system will be nearly identical after a saros, the Moon will be in a slightly different position with respect to the stars for each eclipse in a Saros series.  The axis of rotation of the Earth-Moon system exhibits a precession period of 18.59992 years).

text: After one saros, the Moon will have completed roughly an integer number of lunar orbit cycles and synodic, draconic, and anomalistic periods (241, 223, 242, and 239) and the Earth-Sun-Moon geometry will be nearly identical: the Moon will have the same phase and be at the same node and the same distance from the Earth. In addition, because the saros is close to 18 years in length (about 11 days longer), the earth will be nearly the same distance from the sun, and tilted to it in nearly the same orientation (same season). Given the date of an eclipse, one saros later a nearly identical eclipse can be predicted. During this 18-year period, about 40 other solar and lunar eclipses take place, but with a somewhat different geometry. One saros equaling 18.03 years is not equal to a perfect integer number of lunar orbits (earth revolutions with respect to the fixed stars of 27.32166 days

text: sidereal month

text: ), therefore, even though the relative geometry of the Earth-Sun-Moon system will be nearly identical after a saros, the Moon will be in a slightly different position with respect to the stars for each eclipse in a Saros series.  The axis of rotation of the Earth-Moon system exhibits a

text: precession

text: period of 18.59992 years).

text: It is a relatively rare central eclipse where the moon passes in front of the center of the Earth's shadow. It was the "longest and deepest lunar eclipse to be seen in 7 years". In the total lunar eclipse of July 16, 2000 the moon passed within two arc minutes of the center of the Earth's shadow. In comparison, this still very deep eclipse was off-center by over 12 minutes of arc. The next total lunar eclipse of a longer duration was on June 15, 2011.

text: It is a relatively rare

text: central

text: eclipse where the moon passes in front of the center of the Earth's shadow. It was the "longest and deepest lunar eclipse to be seen in 7 years". In the

text: total lunar eclipse of July 16, 2000

text: the moon passed within two arc minutes of the center of the Earth's shadow. In comparison, this still very deep eclipse was off-center by over 12 minutes of arc. The next total lunar eclipse of a longer duration was on

text: June 15, 2011

text: Pythagoras is a prominent impact crater located near the northwestern limb of the Moon. It lies just to the northwest of the somewhat larger Babbage. The crater has an oval appearance due to the oblique viewing angle. Only the western face of the interior can be viewed from the Earth, the other side being permanently out of sight.

text: Pythagoras

text: is a prominent

text: impact crater

text: located near the northwestern limb of the

text: Moon

text: . It lies just to the northwest of the somewhat larger

text: Babbage

text: . The crater has an oval appearance due to the

text: oblique

text: viewing angle. Only the western face of the interior can be viewed from the Earth, the other side being permanently out of sight.

text: A partial solar eclipse will occur on July 12, 2094. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on July 12, 2094. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A total solar eclipse occurred on August 18, 1868. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on August 18, 1868. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Malapert is a lunar crater that lies near the southern limb of the Moon. From the Earth this formation is viewed from the side, limiting the amount of detail that can be seen. The crater is also illuminated at very low angles, so that parts of the interior remain in almost constant darkness. The nearest craters of note are Cabeus to the west, and Shoemaker to the south-southeast and nearer to the south pole of the Moon.

text: Malapert is a

text: lunar

text: crater

text: that lies near the southern limb of the

text: Moon

text: . From the

text: Earth

text: this formation is viewed from the side, limiting the amount of detail that can be seen. The crater is also illuminated at very low angles, so that parts of the interior remain in almost

text: constant darkness

text: . The nearest craters of note are

text: Cabeus

text: to the west, and

text: Shoemaker

text: to the south-southeast and nearer to the south pole of the Moon.

text: The challenge was to make sense of the apparently irregular wanderings of the planets on the assumption that all heavenly motion is actually circular and uniform in speed.  Why circular?  Because, Plato held, the circle is the most perfect and symmetrical form; therefore circular motion, at uniform speed, was most fitting for celestial bodies.  Aristotle agreed with Plato.  In Aristotle's cosmos, everything has a "natural" tendency to motion that fulfills its inner potential.  For the cosmos' sublunary part (the region below the moon), the natural tendency is to move in a straight line:  downward for earthen things (such as rocks) and water; upward for air and fiery things (such as sparks).  But in the celestial realm things are not composed of earth, water, air or fire, but of a "fifth element", or "quintessence," which is perfect and eternal.  And its natural motion is uniformly circular.  The stars, the sun, the moon and the planets are carried in their orbits by a complicated arrangement of crystalline spheres, all centered around an immobile earth.

text: The challenge was to make sense of the apparently irregular wanderings of the planets on the assumption that all heavenly motion is actually circular and uniform in speed.  Why circular?  Because, Plato held, the

text: circle

text: is the most perfect and symmetrical form; therefore circular motion, at uniform speed, was most fitting for celestial bodies.  Aristotle agreed with Plato.  In Aristotle's

text: cosmos

text: , everything has a "natural" tendency to motion that fulfills its inner potential.  For the cosmos' sublunary part (the region below the moon), the natural tendency is to move in a straight line:  downward for earthen things (such as rocks) and water; upward for air and fiery things (such as sparks).  But in the

text: celestial

text: realm things are not composed of earth, water, air or fire, but of a "fifth element", or "

text: quintessence

text: ," which is perfect and eternal.  And its natural motion is uniformly circular.  The stars, the sun, the moon and the planets are carried in their orbits by a complicated arrangement of crystalline spheres, all centered around an immobile earth.

text: A total solar eclipse occurred on August 21, 1560. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on August 21, 1560. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: A partial solar eclipse occurred on July 19, 1917. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on July 19, 1917. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The Moon is in synchronous rotation: it rotates about its axis in about the same time it takes to orbit Earth. This results in it nearly always keeping the same face turned towards Earth. However, due to the effect of libration, about 59% of the Moon's surface can actually be seen from Earth.

text: The Moon is in

text: synchronous rotation

text: : it rotates about its axis in about the same time it takes to

text: orbit

text: Earth. This results in it nearly always keeping the same face turned towards Earth. However, due to the effect of

text: libration

text: , about 59% of the Moon's surface can actually be seen from Earth.

text: Lunar maria are vast basaltic plains on the Moon that were thought to be bodies of water by early astronomers, who referred to them as "seas". Galileo expressed some doubt about the lunar 'seas' in his Dialogue Concerning the Two Chief World Systems.

text: Lunar maria

text: are vast basaltic plains on the Moon that were thought to be bodies of water by early astronomers, who referred to them as "seas".

text: Galileo

text: expressed some doubt about the lunar 'seas' in his

entity_name: Dialogue Concerning the Two Chief World Systems

text: Dialogue Concerning the Two Chief World Systems

text: Fraunhofer is a lunar crater that is located just to the south-southwest of the walled plain Furnerius, in the southeastern part of the Moon. This crater appears foreshortened when viewed from the Earth, and is actually nearly circular.

text: Fraunhofer is a

text: lunar

text: crater

text: that is located just to the south-southwest of the walled plain

text: Furnerius

text: , in the southeastern part of the

text: Moon

text: . This crater appears foreshortened when viewed from the

text: Earth

text: , and is actually nearly circular.

text: Lunar swirls are enigmatic features found across the Moon’s surface, which are characterized by having a high albedo, appearing optically immature (i.e. having the optical characteristics of a relatively young regolith), and (often) having a sinuous shape. Their curvilinear shape is often accentuated by low albedo regions that wind between the bright swirls. They appear to overlay the lunar surface, superposed on top of craters and ejecta deposits, but impart no observable topography. Swirls have been identified on the lunar maria and highlands - they are not associated with a specific lithologic composition. Swirls on the maria are characterized by strong albedo contrasts and complex, sinuous morphology, whereas those on highland terrain appear less prominent and exhibit simpler shapes, such as single loops or diffuse bright spots.

text: Lunar swirls are enigmatic features found across the

text: Moon

text: ’s surface, which are characterized by having a high

text: albedo

text: , appearing optically immature (i.e. having the optical characteristics of a relatively young

text: regolith

text: ), and (often) having a sinuous shape. Their curvilinear shape is often accentuated by low albedo regions that wind between the bright swirls. They appear to overlay the lunar surface, superposed on top of craters and ejecta deposits, but impart no observable topography. Swirls have been identified on the

text: lunar maria

text: and

text: highlands

text: - they are not associated with a specific lithologic composition. Swirls on the maria are characterized by strong albedo contrasts and complex, sinuous morphology, whereas those on highland terrain appear less prominent and exhibit simpler shapes, such as single loops or diffuse bright spots.

text: The Man in the Moon is made up of various lunar maria (which ones depends on the pareidolic image seen). These vast, flat spots on the moon are called "maria" or "seas" because, for a long time, astronomers believed they were large bodies of water. They are actually large areas formed by lava that covered up old craters and then cooled, becoming smooth, basalt rock.

text: The Man in the Moon is made up of various lunar maria (which ones depends on the pareidolic image seen). These vast, flat spots on the moon are called "maria" or "seas" because, for a long time, astronomers believed they were large bodies of water. They are actually large areas formed by lava that covered up old craters and then cooled, becoming smooth,

text: basalt

text: rock.

text: The following table summarizes the major events and characteristics of the periods of time making up the geologic time scale. As with the time scales above, this time scale is based on the International Commission on Stratigraphy. (See lunar geologic timescale for a discussion of the geologic subdivisions of Earth's moon.) This table is arranged with the most recent geologic periods at the top, and the most ancient at the bottom. The height of each table entry does not correspond to the duration of each subdivision of time.

text: The following table summarizes the major events and characteristics of the periods of time making up the geologic time scale. As with the time scales above, this time scale is based on the International Commission on Stratigraphy. (See

text: lunar geologic timescale

text: for a discussion of the geologic subdivisions of Earth's moon.) This table is arranged with the most recent geologic periods at the top, and the most ancient at the bottom. The height of each table entry does not correspond to the duration of each subdivision of time.

text: Water from lunar sources, Near Earth Asteroids or Martian moons is thought to be relatively cheap and simple to extract, and gives adequate performance for many manufacturing and material shipping purposes. Separation of water into hydrogen and oxygen can be easily performed in small scale, but some scientists  believe that this will not be performed on any large scale initially due to the large quantity of equipment and electrical energy needed to split water and liquify the resultant gases. Water used in steam rockets gives a specific impulse of about 190 seconds; less than half that of hydrogen/oxygen, but this is adequate for delta-v's that are found between Mars and Earth. Water is useful as a radiation shield and in many chemical processes.

text: Water from lunar sources,

text: Near Earth Asteroids

text: or

text: Martian moons

text: is thought to be relatively cheap and simple to extract, and gives adequate performance for many manufacturing and material shipping purposes. Separation of water into hydrogen and oxygen can be easily performed in small scale, but some scientists  believe that this will not be performed on any large scale initially due to the large quantity of equipment and electrical energy needed to split water and liquify the resultant gases. Water used in steam rockets gives a

text: specific impulse

text: of about 190 seconds; less than half that of hydrogen/oxygen, but this is adequate for delta-v's that are found between Mars and Earth. Water is useful as a radiation shield and in many chemical processes.

text: However, these hypotheses were all refuted by the late 1960s and early 1970s Apollo lunar missions, which introduced a stream of new scientific evidence; specifically concerning the Moon's composition, its age, and its history. These lines of evidence contradict many predictions made by these earlier models. The rocks brought back from the Moon showed a marked decrease in water relative to rocks elsewhere in the Solar System, and also evidence of an ocean of magma early in its history, indicating that its formation must have produced a great deal of energy. Also, oxygen isotopes in lunar rocks showed a marked similarity to those on Earth, suggesting that they formed at a similar location in the solar nebula. The capture model fails to explain the similarity in these isotopes (if the Moon had originated in another part of the Solar System, those isotopes would have been different), while the co-accretion model cannot adequately explain the loss of water (if the Moon formed in a similar fashion to the Earth, the amount of water trapped in its mineral structure would also be roughly similar). Conversely, the fission model, while it can account for the similarity in chemical composition and the lack of iron in the Moon, cannot adequately explain its high orbital inclination and, in particular, the large amount of angular momentum in the Earth–Moon system, more than any other planet–satellite pair in the Solar System.

text: However, these hypotheses were all refuted by the late 1960s and early 1970s

text: Apollo

text: lunar missions, which introduced a stream of new scientific evidence; specifically concerning the Moon's composition, its age, and its history. These lines of evidence contradict many predictions made by these earlier models. The rocks brought back from the Moon showed a marked decrease in water relative to rocks elsewhere in the Solar System, and also evidence of an ocean of magma early in its history, indicating that its formation must have produced a great deal of energy. Also, oxygen

text: isotope

text: s in lunar rocks showed a marked similarity to those on Earth, suggesting that they formed at a similar location in the solar nebula. The capture model fails to explain the similarity in these isotopes (if the Moon had originated in another part of the Solar System, those isotopes would have been different), while the co-accretion model cannot adequately explain the loss of water (if the Moon formed in a similar fashion to the Earth, the amount of water trapped in its mineral structure would also be roughly similar). Conversely, the fission model, while it can account for the similarity in chemical composition and the lack of iron in the Moon, cannot adequately explain its high orbital inclination and, in particular, the large amount of angular momentum in the Earth–Moon system, more than any other planet–satellite pair in the Solar System.

text: A partial solar eclipse occurred on August 9, 1953. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 9, 1953. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: If the Moon just revolved around the Earth, there would be no way to tell what fraction of the Moon's or the Earth's gravity was caused by each form of mass, since only the total can be measured. However, the orbit of the Moon is also strongly affected by the gravity of the sun—in essence, Earth and Moon are in freefall around the sun. If the energy portion of mass behaves differently from the conventional portion, then the Earth and the Moon will fall differently toward the Sun, and the orbit of the Moon around the Earth will be affected. For example, suppose the energy part of the mass does affect gravity, but does not affect inertia. Then:

text: The opposite event is called full moon or lunar opposition when sun, earth and moon, in that order, are approximately in a straight line.

text: The Canada Apollo 17 lunar sample display commemorative wooden plaque (10 by 14 inches) consists of one Moon rock particle specimen that was cut from lunar basalt 70017 and a Canadian flag. The basalt 70017 was collected by Apollo 17 astronaut Harrison Schmitt on the Moon in 1972. Once lunar basalt 70017 was brought back to Earth from the Moon, the basalt Moon rock was cut up into small fragments of approximately 1 gram. The specimen was enveloped in a plastic ball and mounted on the wooden plaque along with the Canadian flag which had been taken to the Moon and back by the crew of Apollo 17. The wooden plaque display was then distributed in 1973 by President Richard Nixon to the country of Canada as he did that year to all the countries of the world and all the states of the United States (the same as for the Apollo 11 plaque display gifts). This was done as a goodwill gesture to promote peace and harmony.

text: The Canada Apollo 17 lunar sample display commemorative wooden plaque (10 by 14 inches) consists of one Moon rock particle specimen that was cut from

text: lunar basalt 70017

text: and a Canadian flag. The

text: basalt

text: Harrison Schmitt

text: on the Moon in 1972. Once lunar basalt 70017 was brought back to Earth from the Moon, the basalt Moon rock was cut up into small fragments of approximately 1 gram. The specimen was enveloped in a plastic ball and mounted on the wooden plaque along with the Canadian flag which had been taken to the Moon and back by the crew of Apollo 17. The wooden plaque display was then distributed in 1973 by President Richard Nixon to the country of Canada as he did that year to all the countries of the world and all the states of the United States (the same as for the Apollo 11 plaque display gifts). This was done as a goodwill gesture to promote peace and harmony.

text: China has pursued an ambitious program of lunar exploration, beginning with Chang'e 1, which successfully orbited the Moon from 5 November 2007 until its controlled lunar impact on 1 March 2009. In its sixteen-month mission, it obtained a full image map of the Moon. China followed up this success with Chang'e 2 beginning in October 2010, which reached the Moon over twice as fast as Chang'e 1, mapped the Moon at a higher resolution over an eight-month period, then left lunar orbit in favor of an extended stay at the Earth–Sun L2 Lagrangian point, before finally performing a flyby of asteroid 4179 Toutatis on 13 December 2012, and then heading off into deep space. On 14 December 2013, Chang'e 3 improved upon its orbital mission predecessors by landing a lunar lander onto the Moon's surface, which in turn deployed a lunar rover, named Yutu (Chinese: 玉兔; literally "Jade Rabbit"). In so doing, Chang'e 3 made the first lunar soft landing since Luna 24 in 1976, and the first lunar rover mission since Lunokhod 2 in 1973. China intends to launch another rover mission (Chang'e 4) before 2020, followed by a sample return mission (Chang'e 5) soon after.

text: China has pursued an ambitious

text: program of lunar exploration

text: , beginning with

text: Chang'e 1

text: , which successfully orbited the Moon from 5 November 2007 until its controlled lunar impact on 1 March 2009. In its sixteen-month mission, it obtained a full image map of the Moon. China followed up this success with

text: Chang'e 2

text: beginning in October 2010, which reached the Moon over twice as fast as Chang'e 1, mapped the Moon at a higher resolution over an eight-month period, then left lunar orbit in favor of an extended stay at the Earth–Sun L2

text: Lagrangian point

text: , before finally performing a flyby of asteroid

text: 4179 Toutatis

text: on 13 December 2012, and then heading off into deep space. On 14 December 2013,

text: Chang'e 3

text: improved upon its orbital mission predecessors by landing a lunar

text: lander

text: onto the Moon's surface, which in turn deployed a

text: lunar rover

text: , named Yutu (Chinese: 玉兔; literally "Jade Rabbit"). In so doing, Chang'e 3 made the first lunar

text: soft landing

text: since

text: Luna 24

text: in 1976, and the first lunar rover mission since

text: Lunokhod 2

text: in 1973. China intends to launch another rover mission (

text: Chang'e 4

text: ) before 2020, followed by a

text: sample return mission

text: Chang'e 5

text: ) soon after.

text: As used in the space program, this refers not to the orbit of the Moon about the Earth, but to orbits by various manned or unmanned spacecraft around the Moon. The altitude at apoapsis (point farthest from the surface) for a lunar orbit is known as apolune, apocynthion or aposelene, while the periapsis (point closest to the surface) is known as perilune, pericynthion or periselene, from names or epithets of the moon goddess.

text: As used in the

text: space program

text: , this refers not to the orbit of the Moon about the

text: Earth

text: , but to orbits by various manned or unmanned spacecraft around the Moon. The altitude at

text: apoapsis

text: (point farthest from the surface) for a lunar orbit is known as apolune, apocynthion or aposelene, while the

text: periapsis

text: (point closest to the surface) is known as perilune, pericynthion or periselene, from names or epithets of the

text: moon goddess

text: As observed from the Earth, a solar eclipse occurs when the Moon passes in front of the Sun. The type of solar eclipse event depends on the distance of the Moon from the Earth during the event. A total solar eclipse occurs when the Earth intersects the umbra portion of the Moon's shadow. When the umbra does not reach the surface of the Earth, the Sun is only partially occulted, resulting in an annular eclipse. Partial solar eclipses occur when the viewer is inside the penumbra.

text: As observed from the Earth, a

text: solar eclipse

text: occurs when the Moon passes in front of the Sun. The type of solar eclipse event depends on the distance of the Moon from the Earth during the event. A total solar eclipse occurs when the Earth intersects the umbra portion of the Moon's shadow. When the umbra does not reach the surface of the Earth, the Sun is only partially occulted, resulting in an annular eclipse. Partial solar eclipses occur when the viewer is inside the penumbra.

text: This is a list of maria (large, dark, basaltic plains) on the Moon. It also includes the one oceanus and the features known by the names lacus, palus and sinus. The modern system of lunar nomenclature was introduced in 1651 by Giovanni Battista Riccioli. Riccioli's map of the moon was drawn by Francesco Maria Grimaldi, who has a crater named after him.

text: This is a list of

text: maria

text: (large, dark,

text: basalt

text: ic plains) on the

text: Moon

text: . It also includes the one oceanus and the features known by the names lacus, palus and sinus. The modern system of lunar nomenclature was introduced in 1651 by Giovanni Battista

text: Riccioli

text: . Riccioli's map of the moon was drawn by

text: Francesco Maria Grimaldi

text: , who has a crater named after him.

text: Chrétien is a lunar crater that is located in the southern hemisphere on the far side of the Moon from the Earth. It lies due south of the Mare Ingenii, one of the few maria on the Moon's far side. The crater lies in the midpoint between the craters Garavito to the west-southwest and Oresme to the east-northeast, both of these being somewhat smaller than Chrétien.

text: Chrétien is a

text: lunar

text: crater

text: that is located in the southern

text: hemisphere

text: on the

text: far side

text: of the

text: Moon

text: from the

text: Earth

text: . It lies due south of the

text: Mare Ingenii

text: , one of the few

text: maria

text: on the Moon's far side. The crater lies in the midpoint between the craters

text: Garavito

text: to the west-southwest and

text: Oresme

text: to the east-northeast, both of these being somewhat smaller than Chrétien.

text: By the late 1890s, American scientist Samuel Pierpoint Langley had attempted to determine the surface temperature of the Moon by measuring infrared radiation leaving the Moon and reaching the Earth. The angle of the Moon in the sky when a scientist took a measurement determined how much  and water vapor the Moon's radiation had to pass through to reach the Earth's surface, resulting in weaker measurements when the Moon was low in the sky.  This result was unsurprising given that scientists had known about infrared radiation absorption for decades.

text: By the late 1890s, American scientist

text: Samuel Pierpoint Langley

text: had attempted to determine the surface temperature of the Moon by measuring infrared radiation leaving the Moon and reaching the Earth. The angle of the Moon in the sky when a scientist took a measurement determined how much  and water vapor the Moon's radiation had to pass through to reach the Earth's surface, resulting in weaker measurements when the Moon was low in the sky.  This result was unsurprising given that scientists had known about

text: infrared radiation absorption

text: for decades.

text: On November 1, 2016 NASA issued a Request for Information (RFI) about possible small lunar surface payloads that can be delivered to the Moon's surface in the 2017-2020 time-frame using U.S. commercial lunar cargo transportation service providers. Of particular interest were payloads that address NASA's strategic objectives including filling one or more of NASA's lunar exploration Strategic Knowledge Gaps (SKGs).

text: de Gerlache is a lunar crater that is located along the southern limb of the Moon, within a crater diameter of Shackleton at the south pole. From the Earth this crater is seen from the edge, and it lies in perpetual darkness. Thus little or no detail can be seen of this crater, other than the edge of the rim. However, the crater is clearly visible in Earth-based radar images. The crater is roughly circular, with some slight wear. No craters of note overlie the rim, although some formations may be attached to the southern and western edges.

text: de Gerlache is a

text: lunar

text: crater

text: that is located along the southern limb of the

text: Moon

text: , within a crater diameter of

text: Shackleton

text: at the

text: south pole

text: . From the

text: Earth

text: this crater is seen from the edge, and it lies in perpetual darkness. Thus little or no detail can be seen of this crater, other than the edge of the

text: rim

text: . However, the crater is clearly visible in Earth-based radar images. The crater is roughly circular, with some slight wear. No craters of note overlie the rim, although some formations may be attached to the southern and western edges.

text: Petzval is a lunar impact crater that lies in the southern latitudes of the Moon's far side. This crater is located to the south of the larger Lippmann, and to the north of Doerfel. It was namer after the Hungarian-German inventor Joseph Petzval.

text: Petzval is a

text: lunar

text: impact crater

text: that lies in the southern latitudes of the

text: Moon

text: 's

text: far side

text: . This crater is located to the south of the larger

text: Lippmann

text: , and to the north of

text: Doerfel

text: . It was namer after the

text: Hungarian-German

text: inventor

text: Joseph Petzval

text: In the 2nd century CE, Ptolemy estimated the mean distance of the Sun as  times Earth's radius. To determine this value, Ptolemy started by measuring the Moon's parallax, finding what amounted to a horizontal lunar parallax of 1° 26′, which was much too large. He then derived a maximum lunar distance of 64 Earth radii. Because of cancelling errors in his parallax figure, his theory of the Moon's orbit, and other factors, this figure was approximately correct. He then measured the apparent sizes of the Sun and the Moon and concluded that the apparent diameter of the Sun was equal to the apparent diameter of the Moon at the Moon's greatest distance, and from records of lunar eclipses, he estimated this apparent diameter, as well as the apparent diameter of the shadow cone of Earth traversed by the Moon during a lunar eclipse. Given these data, the distance of the Sun from Earth can be trigonometrically computed to be  Earth radii. This gives a ratio of solar to lunar distance of approximately 19, matching Aristarchus's figure. Although Ptolemy's procedure is theoretically workable, it is very sensitive to small changes in the data, so much so that changing a measurement by a few percent can make the solar distance infinite.

text: In the 2nd century CE,

text: Ptolemy

text: estimated the mean distance of the Sun as  times

text: Earth's radius

text: . To determine this value, Ptolemy started by measuring the Moon's parallax, finding what amounted to a horizontal lunar parallax of 1° 26′, which was much too large. He then derived a maximum lunar distance of 64 Earth radii. Because of cancelling errors in his parallax figure, his theory of the Moon's orbit, and other factors, this figure was approximately correct. He then measured the apparent sizes of the Sun and the Moon and concluded that the apparent diameter of the Sun was equal to the apparent diameter of the Moon at the Moon's greatest distance, and from records of lunar eclipses, he estimated this apparent diameter, as well as the apparent diameter of the shadow cone of Earth traversed by the Moon during a lunar eclipse. Given these data, the distance of the Sun from Earth can be trigonometrically computed to be  Earth radii. This gives a ratio of solar to lunar distance of approximately 19, matching Aristarchus's figure. Although Ptolemy's procedure is theoretically workable, it is very sensitive to small changes in the data, so much so that changing a measurement by a few percent can make the solar distance infinite.

text: The mythical words established the three worlds (water, air and earth) based on the prologue of the Serer genesis provided by A nax. In A leep, it gives the order in which they were created and elaborated on it. A leep posits that, with the words of Roog, the three worlds (the Universe) began to take shape. The first to be created was the deep sea waters (waters of the underworld); the second was air including the high heavens (Kuul na, in Serer) such as the sun, the moon and the stars; and third was earth. However, the Earth was not one of the first primordial worlds to be formed. It will take a long time before the waters and the Earth were separated.

text: The mythical words established the three worlds (water, air and earth) based on the

text: prologue

text: of the Serer genesis provided by A nax. In A leep, it gives the order in which they were created and elaborated on it. A leep posits that, with the words of Roog, the three worlds (the

text: Universe

text: ) began to take shape. The first to be created was the deep sea waters (waters of the

text: underworld

text: ); the second was

text: air

text: including the high heavens (Kuul na, in

text: Serer

text: ) such as the

text: sun

text: , the

text: moon

text: and the

text: stars

text: ; and third was earth. However, the

text: Earth

text: was not one of the first primordial worlds to be formed. It will take a long time before the waters and the Earth were separated.

text: A partial solar eclipse will occur on July 22, 2047. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on July 22, 2047. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Lunar craters are impact craters on Earth's Moon. The Moon's surface has many craters, almost all of which were formed by impacts.

text: Lunar craters are

text: impact crater

text: s on

text: Earth

text: 's

text: Moon

text: . The Moon's surface has many craters, almost all of which were formed by impacts.

text: Anno 2205 is a futuristic city-building video game similar to Anno 2070, as opposed to the previous installments which feature a historical setting. In the game, players take on the role of a leader from a corporation and must compete against other corporations in developing future technologies. At the beginning of the game, players are tasked to build different metropolises on Earth. Population increases when more buildings are built, and players are tasked to satisfy and fulfill the needs of their citizens. Besides building houses, players must also produce goods and build infrastructures like robot production facilities to maintain economy, where said buildings can be relocated or moved around by players. Similar to SimCity, different parts can be added to buildings to enhance their functions. Upgrading the production structures of these buildings can also improve their efficiency. When citizens' demands were satisfied, they are able to produce more goods. Eventually players are asked to develop and conduct research in arctic regions in order to find cost-efficient ways to launch rockets to the moon and upon completion, players may colonize the moon and build cities inside its craters. Resources of the moon, such as Helium-3, are vital to the development of the cities on earth and can be sent back to earth. Gameplay differs when players are establishing an outpost in the arctic regions or on the moon. In the arctic regions players must manage the heating areas of the outpost. As the moon lacks an atmosphere and features a grimmer environment than Earth, building a city on the moon requires erecting asteroid shields, as well as unique greenhouses to produce food. Anno 2205 also includes a fully functional day and night cycle for different visuals.

text: Anno 2205 is a futuristic

text: city-building video game

text: similar to

text: Anno 2070

text: , as opposed to the previous installments which feature a historical setting. In the game, players take on the role of a leader from a corporation and must compete against other corporations in developing future technologies. At the beginning of the game, players are tasked to build different metropolises on Earth. Population increases when more buildings are built, and players are tasked to satisfy and fulfill the needs of their citizens. Besides building houses, players must also produce goods and build infrastructures like robot production facilities to maintain economy, where said buildings can be relocated or moved around by players. Similar to

text: SimCity

text: , different parts can be added to buildings to enhance their functions. Upgrading the production structures of these buildings can also improve their efficiency. When citizens' demands were satisfied, they are able to produce more goods. Eventually players are asked to develop and conduct research in arctic regions in order to find cost-efficient ways to launch rockets to the moon and upon completion, players may colonize the moon and build cities inside its craters. Resources of the moon, such as Helium-3, are vital to the development of the cities on earth and can be sent back to earth. Gameplay differs when players are establishing an outpost in the arctic regions or on the moon. In the arctic regions players must manage the heating areas of the outpost. As the moon lacks an atmosphere and features a grimmer environment than Earth, building a city on the moon requires erecting asteroid shields, as well as unique greenhouses to produce food. Anno 2205 also includes a fully functional day and night cycle for different visuals.

text: Over millions of years, the Earth's rotation slowed significantly by tidal acceleration through gravitational interactions with the Moon. In this process, angular momentum is slowly transferred to the Moon at a rate proportional to

text: Over millions of years, the Earth's rotation slowed significantly by

text: tidal acceleration

text: through gravitational interactions with the Moon. In this process,

text: angular momentum

text: is slowly transferred to the Moon at a rate proportional to

text: As a result of the Moon's synchronous rotation, one side of the Moon (the "near side") is permanently turned towards Earth, and the other side, the "far side", mostly cannot be seen from Earth. This means, conversely, that Earth can only be seen from the near side of the Moon and would always be invisible from the far side.If the Moon's rotation were purely synchronous, Earth would not have any noticeable movement in the Moon's sky. However, due to the Moon's libration, Earth does perform a slow and complex wobbling movement. Once a month, as seen from the Moon, Earth traces out an approximate oval of diameter 18°. The exact shape and orientation of this oval depend on one's location on the Moon. As a result, near the boundary of the near and far sides of the Moon, Earth is sometimes below the horizon and sometimes above it.

text: As a result of the Moon's

text: synchronous rotation

text: , one side of the Moon (the "

text: near side

text: ") is permanently turned towards Earth, and the other side, the "

text: far side

text: ", mostly cannot be seen from Earth. This means, conversely, that Earth can only be seen from the near side of the Moon and would always be invisible from the far side.If the Moon's rotation were purely synchronous, Earth would not have any noticeable movement in the Moon's sky. However, due to the Moon's

text: libration

text: , Earth does perform a slow and complex wobbling movement. Once a month, as seen from the Moon, Earth traces out an approximate oval of diameter 18°. The exact shape and orientation of this oval depend on one's location on the Moon. As a result, near the boundary of the near and far sides of the Moon, Earth is sometimes below the

text: horizon

text: and sometimes above it.

text: A shadow cast by the Earth on the Moon is a lunar eclipse. Conversely, a shadow cast by the Moon on the Earth is a solar eclipse.

text: A shadow cast by the

text: Earth

text: on the

text: Moon

text: is a

text: lunar eclipse

text: . Conversely, a shadow cast by the Moon on the Earth is a

text: solar eclipse

text: Rittenhouse is a small lunar crater that is located in the southern part of the Moon's far side. It lies amidst the western outer ramparts of the immense walled plain Schrödinger. To the west is the prominent crater Hale, just visible from the Earth along the lunar limb.

text: Rittenhouse is a small

text: lunar

text: crater

text: Moon

text: 's

text: far side

text: . It lies amidst the western outer

text: rampart

text: s of the immense walled plain

text: Schrödinger

text: . To the west is the prominent crater

text: Hale

text: , just visible from the

text: Earth

text: along the lunar limb.

text: This is a directory of lists of geological features on planets excepting Earth, moons and asteroids ordered by increasing distance from the Sun.

text: This is a directory of lists of geological features on

text: planet

text: s excepting

text: Earth

text: moon

text: s and

text: asteroid

text: s ordered by increasing distance from the

text: Sun

text: The far side has more visible craters. This was thought to be a result of the effects of lunar lava flows, which cover and obscure craters, rather than a shielding effect from the Earth. NASA calculates that the Earth obscures only about 4 square degrees out of 41,000 square degrees of the sky as seen from the Moon.  "This makes the Earth negligible as a shield for the Moon. . . . It is likely that each side of the Moon has received equal numbers of impacts, but the resurfacing by lava results in fewer craters visible on the near side than the far side, even though the [sic] both sides have received the same number of impacts."

text: Titov is a relatively small lunar impact crater on the far side of the Moon. The most unusual aspect of this crater is that it is located entirely within the Mare Moscoviense, one of the few maria found on the far side of the Moon. It lies to the northwest of the crater Komarov, in the northern half of the mare.  It is named for cosmonaut Gherman Titov, the second person to orbit the Earth.

text: Titov is a relatively small

text: lunar

text: impact crater

text: on the

text: far side

text: of the

text: Moon

text: . The most unusual aspect of this crater is that it is located entirely within the

text: Mare Moscoviense

text: , one of the few

text: maria

text: found on the far side of the Moon. It lies to the northwest of the crater

text: Komarov

text: , in the northern half of the mare.  It is named for

text: cosmonaut

text: Gherman Titov

text: , the second person to orbit the Earth.

text: Earth was initially molten due to extreme volcanism and frequent collisions with other bodies. Eventually, the outer layer of the planet cooled to form a solid crust when water began accumulating in the atmosphere. The Moon formed soon afterwards, possibly as a result of the impact of a large planetoid with the Earth. Some of this object's mass merged with the Earth, significantly altering its internal composition, and a portion was ejected into space. Some of the material survived to form an orbiting moon. More recent potassium isotopic studies suggest that the Moon was formed by a smaller, high-energy, high-angular-momentum giant impact cleaving off a significant portion of the Earth. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, augmented by ice delivered from comets, produced the oceans.

text: Earth

text: was initially molten due to extreme

text: volcanism

text: and frequent collisions with other bodies. Eventually, the outer layer of the planet cooled to form a solid

text: crust

text: when water began accumulating in the atmosphere. The

text: Moon

text: formed soon afterwards, possibly as a result of the

text: impact

text: of a large planetoid with the Earth. Some of this object's mass merged with the Earth, significantly altering its internal composition, and a portion was ejected into space. Some of the material survived to form an orbiting moon. More recent potassium isotopic studies suggest that the Moon was formed by a smaller, high-energy, high-angular-momentum giant impact cleaving off a significant portion of the Earth. Outgassing and

text: volcanic

text: activity produced the primordial atmosphere. Condensing

text: water vapor

text: , augmented by ice delivered from

text: comet

text: s,

text: produced the oceans

text: Earth was initially molten due to extreme volcanism and frequent collisions with other bodies. Eventually, the outer layer of the planet cooled to form a solid crust when water began accumulating in the atmosphere. The Moon formed soon afterwards, possibly as a result of the impact of a planetoid with the Earth. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, augmented by ice delivered from comets, produced the oceans.

text: Earth was initially molten due to extreme

text: volcanism

text: crust

text: Moon

text: formed soon afterwards, possibly as a result of the impact of a planetoid with the Earth.

text: Outgassing

text: and volcanic activity produced the primordial atmosphere. Condensing

text: water vapor

text: , augmented by ice delivered from

text: comet

text: s,

text: produced the oceans

text: The Moon is gradually receding from Earth into a higher orbit, and calculations suggest that this would continue for about 50 billion years. By that time, Earth and the Moon would be in a mutual spin–orbit resonance or tidal locking, in which the Moon will orbit Earth in about 47 days (currently 27 days), and both the Moon and Earth would rotate around their axes in the same time, always facing each other with the same side. This has already happened to the Moon—the same side always faces Earth—and is also slowly happening to the Earth. However, the slowdown of Earth's rotation is not occurring fast enough for the rotation to lengthen to a month before other effects change the situation: approximately 2.3 billion years from now, the increase of the Sun's radiation will have caused Earth's oceans to evaporate, removing the bulk of the tidal friction and acceleration.

text: The Moon is gradually receding from Earth into a higher orbit, and calculations suggest that this would continue for about 50 billion years. By that time, Earth and the Moon would be in a mutual spin–orbit resonance or

text: tidal locking

text: , in which the Moon will orbit Earth in about 47 days (currently 27 days), and both the Moon and Earth would rotate around their axes in the same time, always facing each other with the same side. This has already happened to the Moon—the same side always faces Earth—and is also slowly happening to the Earth. However, the slowdown of Earth's rotation is not occurring fast enough for the rotation to lengthen to a month before other effects change the situation: approximately 2.3 billion years from now, the increase of the Sun's

text: radiation

text: will have caused Earth's oceans to evaporate, removing the bulk of the tidal friction and acceleration.

text: Another issue is lunar and Earth isotope comparisons. In 2001, the most precise measurement yet of the isotopic signatures of lunar rocks was published. Surprisingly, the Apollo lunar samples carried an isotopic signature identical to Earth rocks, but different from other Solar system bodies. Because most of the material that went into orbit to form the Moon was thought to come from Theia, this observation was unexpected. In 2007, researchers from Caltech showed that the likelihood of Theia having an identical isotopic signature as the Earth is very small (<1 percent). Published in 2012, an analysis of titanium isotopes in Apollo lunar samples showed that the Moon has the same composition as Earth, which conflicts with the Moon forming far from Earth's orbit.

text: Another issue is lunar and Earth isotope comparisons. In 2001, the most precise measurement yet of the isotopic signatures of lunar rocks was published. Surprisingly, the

text: Apollo

text: lunar samples carried an isotopic signature identical to Earth rocks, but different from other Solar system bodies. Because most of the material that went into orbit to form the Moon was thought to come from Theia, this observation was unexpected. In 2007, researchers from Caltech showed that the likelihood of Theia having an identical isotopic signature as the Earth is very small (<1 percent). Published in 2012, an analysis of titanium isotopes in Apollo lunar samples showed that the Moon has the same composition as Earth, which

text: conflicts

text: with the Moon forming far from Earth's orbit.

text: Ingalls is an old lunar crater that lies on the far side of the Moon. It is located to the north-northwest of the walled plain Mach. About the same distance to the west is the crater Joule.

text: Ingalls is an old

text: lunar

text: crater

text: that lies on the

text: far side

text: of the

text: Moon

text: . It is located to the north-northwest of the walled plain

text: Mach

text: . About the same distance to the west is the crater

text: Joule

text: Richardson is a large lunar crater located on the Moon's far side, just behind the eastern limb. It lies to the south of the huge walled plain Harkhebi, and to the east-southeast of the crater Vestine. Just to the northeast is Szilard, and to the southeast is Artamonov.

text: Richardson is a large

text: lunar

text: crater

text: located on the

text: Moon

text: 's

text: far side

text: , just behind the eastern limb. It lies to the south of the huge walled plain

text: Harkhebi

text: Vestine

text: . Just to the northeast is

text: Szilard

text: , and to the southeast is

text: Artamonov

text: Spaceports have been proposed for locations on the Moon, Mars, orbiting the Earth, at Sun-Earth and Earth-Moon Lagrange points, and at other locations in the solar system.  Human-tended outposts on the Moon or Mars, for example, will be spaceports by definition. The 2012 Space Studies Program of the International Space University studied the economic benefit of a network of spaceports throughout the solar system beginning from Earth and expanding outwardly in phases, within its team project Operations And Service Infrastructure for Space (OASIS). Its analysis claimed that the first phase, placing the "Node 1" spaceport with space tug services in Low Earth Orbit (LEO), would be commercially profitable and reduce transportation costs to geosynchronous orbit by as much as 44% (depending on the launch vehicle).  The second phase would add a Node 2 spaceport on the lunar surface to provide services including lunar ice mining and delivery of rocket propellants back to Node 1.  This would enable lunar surface activities and further reduce transportation costs within and out from cislunar space.  The third phase would add a Node 3 spaceport on the Martian moon Phobos to enable refueling and resupply prior to Mars surface landings, missions beyond Mars, and return trips to Earth.  In addition to propellant mining and refueling, the network of spaceports could provide services such as power storage and distribution, in-space assembly and repair of spacecraft, communications relay, shelter, construction and leasing of infrastructure, maintaining spacecraft positioned for future use, and logistics.

text: Spaceports have been proposed for locations on the

text: Moon

text: Mars

text: , orbiting the Earth, at Sun-Earth and Earth-Moon

text: Lagrange point

text: s, and at other locations in the

text: solar system

text: .  Human-tended outposts on the Moon or Mars, for example, will be spaceports by definition. The 2012 Space Studies Program of the

text: International Space University

text: studied the economic benefit of a network of spaceports throughout the solar system beginning from Earth and expanding outwardly in phases, within its team project Operations And Service Infrastructure for Space (OASIS). Its analysis claimed that the first phase, placing the "Node 1" spaceport with space tug services in

text: Low Earth Orbit

text: (LEO), would be commercially profitable and reduce transportation costs to

text: geosynchronous orbit

text: by as much as 44% (depending on the launch vehicle).  The second phase would add a Node 2 spaceport on the lunar surface to provide services including

text: lunar ice

text: mining and delivery of rocket

text: propellant

text: s back to Node 1.  This would enable lunar surface activities and further reduce transportation costs within and out from

text: cislunar

text: space.  The third phase would add a Node 3 spaceport on the Martian moon

text: Phobos

text: to enable refueling and resupply prior to Mars surface landings, missions beyond Mars, and return trips to Earth.  In addition to propellant mining and refueling, the network of spaceports could provide services such as power storage and distribution, in-space assembly and repair of spacecraft, communications relay, shelter, construction and leasing of infrastructure, maintaining spacecraft positioned for future use, and logistics.

text: In Aristotle's (384–322 BC) description of the universe, the Moon marked the boundary between the spheres of the mutable elements (earth, water, air and fire), and the imperishable stars of aether, an influential philosophy that would dominate for centuries. However, in the , Seleucus of Seleucia correctly theorized that tides were due to the attraction of the Moon, and that their height depends on the Moon's position relative to the Sun. In the same century, Aristarchus computed the size and distance of the Moon from Earth, obtaining a value of about twenty times the radius of Earth for the distance. These figures were greatly improved by Ptolemy (90–168 AD): his values of a mean distance of 59 times Earth's radius and a diameter of 0.292 Earth diameters were close to the correct values of about 60 and 0.273 respectively. Archimedes (287–212 BC) designed a planetarium that could calculate the motions of the Moon and other objects in the Solar System.

text: In

text: Aristotle

text: 's (384–322 BC)

text: description of the universe

text: , the Moon marked the boundary between the spheres of the mutable elements (earth, water, air and fire), and the imperishable stars of

text: aether

text: , an

text: influential philosophy

text: that would dominate for centuries. However, in the ,

text: Seleucus of Seleucia

text: correctly theorized that

text: tide

text: s were due to the attraction of the Moon, and that their height depends on the Moon's position relative to the

text: Sun

text: . In the same century,

text: Aristarchus

entity_name: On the Sizes and Distances (Aristarchus)

text: computed the size and distance

text: of the Moon from Earth, obtaining a value of about twenty times the

text: radius of Earth

text: for the distance. These figures were greatly improved by

text: Ptolemy

text: (90–168 AD): his values of a mean distance of 59 times Earth's radius and a diameter of 0.292 Earth diameters were close to the correct values of about 60 and 0.273 respectively.

text: Archimedes

text: (287–212 BC) designed a planetarium that could calculate the motions of the Moon and other objects in the Solar System.

text: Cavor's account explains that Selenites exist in thousands of forms and find fulfillment in carrying out the specific social function for which they have been brought up: specialization is the essence of Selenite society. "With knowledge the Selenites grew and changed; mankind stored their knowledge about them and remained brutes—equipped," remarks the Grand Lunar, when he finally meets Cavor and hears about life on Earth. Unfortunately, Cavor reveals humanity's propensity for war; the lunar leader and those listening to the interview are "stricken with amazement".  Bedford infers that it is for this reason that Cavor has been prevented from further broadcasting to Earth. Cavor's transmissions are cut off as he is trying to describe how to make cavorite.  His final fate is unknown, but Bedford is sure that "we shall never… receive another message from the moon".

text: Cavor's account explains that Selenites exist in thousands of forms and find fulfillment in carrying out the specific social function for which they have been brought up:

text: specialization

text: is the essence of Selenite society. "With knowledge the Selenites grew and changed; mankind stored their knowledge about them and remained brutes—equipped," remarks the Grand Lunar, when he finally meets Cavor and hears about life on Earth. Unfortunately, Cavor reveals humanity's propensity for

text: war

text: ; the lunar leader and those listening to the interview are "stricken with amazement".  Bedford infers that it is for this reason that Cavor has been prevented from further broadcasting to Earth. Cavor's transmissions are cut off as he is trying to describe how to make cavorite.  His final fate is unknown, but Bedford is sure that "we shall never… receive another message from the moon".

text: In the UFO TV series, the Lunar module is the only SHADO spacecraft capable of Earth-Moon travel. On Earth, it can only takeoff and land docked with a mother ship known as the Lunar Carrier, as part of its tail.

text: In the

text: UFO

text: TV series, the Lunar module is the only SHADO

text: spacecraft

text: capable of Earth-Moon travel. On Earth, it can only takeoff and land docked with a

text: mother ship

text: known as the Lunar Carrier, as part of its tail.

text: When asked in 1930 what inspired him for A Trip to the Moon, Méliès credited Jules Verne's novels From the Earth to the Moon and Around the Moon. Cinema historians, the mid-20th-century French writer Georges Sadoul first among them, have frequently suggested H. G. Wells's The First Men in the Moon, a French translation of which was published a few months before Méliès made the film, as another likely influence. Sadoul argued that the first half of the film (up to the shooting of the projectile) is derived from Verne and that the second half (the travelers' adventures on and in the moon) is derived from Wells.

text: When asked in 1930 what inspired him for A Trip to the Moon, Méliès credited

text: Jules Verne

text: 's novels

text: From the Earth to the Moon

text: and

text: Around the Moon

text: . Cinema historians, the mid-20th-century French writer

text: Georges Sadoul

text: first among them, have frequently suggested

text: H. G. Wells

text: 's

text: The First Men in the Moon

text: , a French translation of which was published a few months before Méliès made the film, as another likely influence. Sadoul argued that the first half of the film (up to the shooting of the projectile) is derived from Verne and that the second half (the travelers' adventures on and in the moon) is derived from Wells.

text: The effect on a lunar eclipse is quite similar, with a few differences. First, the eclipsed body is the Moon and the eclipsing 'body' is the Earth's shadow. Second, since the Earth's shadow at the Moon's distance always is considerably larger than the Moon, a lunar eclipse can never be annular but is always partial or total. Third, the Earth's shadow has two components: the dark umbra and the much brighter penumbra. A lunar eclipse will have two geometric magnitudes: the umbral magnitude and the penumbral magnitude. If the three bodies are not aligned enough, the Moon does not reach into the Earth's umbra - it may still pass through the Earth's penumbra though, and such an eclipse is called a penumbral eclipse.

text: The effect on a lunar eclipse is quite similar, with a few differences. First, the eclipsed body is the Moon and the eclipsing 'body' is the Earth's shadow. Second, since the Earth's shadow at the Moon's distance always is considerably larger than the Moon, a lunar eclipse can never be annular but is always partial or total. Third, the Earth's shadow has two components: the dark

text: umbra

text: and the much brighter

text: penumbra

text: . A lunar eclipse will have two geometric magnitudes: the umbral magnitude and the penumbral magnitude. If the three bodies are not aligned enough, the Moon does not reach into the Earth's umbra - it may still pass through the Earth's penumbra though, and such an eclipse is called a

text: penumbral eclipse

text: Gill is a lunar crater that is located near the southeastern limb of the Moon. Due to its proximity to the edge of the Moon as seen from the Earth, this crater is viewed nearly from the side and it can become hidden from sight due to libration. The crater lies to the southwest of the irregular Mare Australe, and southeast of the prominent crater Pontécoulant. To the southwest of Gill is the crater Helmholtz.

text: Gill is a

text: lunar

text: crater

text: that is located near the southeastern limb of the

text: Moon

text: . Due to its proximity to the edge of the Moon as seen from the

text: Earth

text: , this crater is viewed nearly from the side and it can become hidden from sight due to

text: libration

text: . The crater lies to the southwest of the irregular

text: Mare Australe

text: , and southeast of the prominent crater

text: Pontécoulant

text: . To the southwest of Gill is the crater

text: Helmholtz

text: The Historic England listing for the Half Moon Public House states that, "The proliferation of ornament across the surface of this building gives the whole a sense of vital unity through their sheer number." The Half Moon is also listed by CAMRA as, "A pub with a nationally important historic interior." Only 270 pubs meet CAMRA's exacting criteria and the Half Moon is one of them. The snug bar contains six back-painted mirrors depicting birds and signed by the renowned ‘W. Gibbs & Sons glass decorators’ of Blackfriars. Photos of the pub from the first part of the 20th century, show it to be operated by Barclay Perkins & Co. The rear of the Half Moon comprises both an original element forming a billiards room, and a later addition constructed during the 1930s to convert this area into a snooker room. These two activities are still advertised in the stained glasswork on the outside of the pub.

text: The

text: Historic England

text: listing for the Half Moon Public House states that, "The proliferation of ornament across the surface of this building gives the whole a sense of vital unity through their sheer number." The Half Moon is also listed by

text: CAMRA

text: as, "A pub with a nationally important historic interior." Only 270 pubs meet

text: CAMRA

text: 's exacting criteria and the Half Moon is one of them. The snug bar contains six back-painted mirrors depicting birds and signed by the renowned ‘W. Gibbs & Sons glass decorators’ of Blackfriars. Photos of the pub from the first part of the 20th century, show it to be operated by

text: Barclay Perkins

text: & Co. The rear of the Half Moon comprises both an original element forming a billiards room, and a later addition constructed during the 1930s to convert this area into a snooker room. These two activities are still advertised in the stained glasswork on the outside of the pub.

text: Lallemand is a small lunar impact crater that lies near the western limb of the Moon, in a region where the visibility is affected by libration effects. Because of its location, when viewed from the Earth the crater is viewed nearly from the side, limiting the amount of detail that can be seen. It lies in the northeast part of a mountain range named the Montes Rook that forms a ring around the enormous Mare Orientale impact basin. To the northeast is the Lacus Autumni and to the northwest lies the Lacus Veris, both forming small lunar maria along the sides of the range.

text: Lallemand is a small

text: lunar

text: impact crater

text: that lies near the western limb of the

text: Moon

text: , in a region where the visibility is affected by

text: libration

text: effects. Because of its location, when viewed from the

text: Earth

text: the crater is viewed nearly from the side, limiting the amount of detail that can be seen. It lies in the northeast part of a mountain range named the

text: Montes Rook

text: that forms a ring around the enormous

text: Mare Orientale

text: impact basin. To the northeast is the

text: Lacus Autumni

text: and to the northwest lies the

text: Lacus Veris

text: , both forming small

text: lunar maria

text: along the sides of the range.

text: The umbra (Latin for "shadow") is the innermost and darkest part of a shadow, where the light source is completely blocked by the occluding body. Such as an opaque object does not let light through it. An observer in the umbra experiences a total eclipse. The umbra of a round body occluding a round light source forms a right circular cone; to a viewer at the cone's apex, the two bodies are equal in apparent size. The distance from the Moon to the apex of its umbra is roughly equal to that between the Moon and Earth.  Because the Earth is 3.7 times wider than the Moon, its umbra extends correspondingly farther, roughly 1.4 million kilometers.

text: The umbra (Latin for "shadow") is the innermost and darkest part of a shadow, where the light source is completely blocked by the occluding body. Such as an opaque object does not let light through it. An observer in the umbra experiences a total eclipse. The umbra of a round body occluding a round light source forms a

text: right circular cone

text: ; to a viewer at the cone's apex, the two bodies are equal in

text: apparent size

text: . The distance from the Moon to the apex of its umbra is roughly equal to that between the Moon and Earth.  Because the Earth is 3.7 times wider than the Moon, its umbra extends correspondingly farther, roughly 1.4 million kilometers.

text: Volta is a lunar crater near the northwest limb of the Moon. It is located south-southeast of the crater Xenophanes, and due north of the smaller Galvani. The crater Regnault lies across the western rim of Volta. Attached to the southwest rim of Volta and the southern rim of Regnault is Stokes. Lying between Volta and Stokes in the north, and Galvani in the south, is the worn Langley.

text: Volta is a

text: lunar

text: crater

text: near the northwest limb of the

text: Moon

text: . It is located south-southeast of the crater

text: Xenophanes

text: , and due north of the smaller

text: Galvani

text: . The crater

text: Regnault

text: lies across the western rim of Volta. Attached to the southwest rim of Volta and the southern rim of Regnault is

text: Stokes

text: . Lying between Volta and Stokes in the north, and Galvani in the south, is the worn

text: Langley

text: There are three types of lunar eclipses: penumbral, when the Moon crosses only the Earth's penumbra; partial, when the Moon crosses partially into the Earth's umbra; and total, when the Moon crosses entirely into the Earth's umbra. Total lunar eclipses pass through all three phases. Even during a total lunar eclipse, however, the Moon is not completely dark. Sunlight refracted through the Earth's atmosphere enters the umbra and provides a faint illumination. Much as in a sunset, the atmosphere tends to more strongly scatter light with shorter wavelengths, so the illumination of the Moon by refracted light has a red hue, thus the phrase 'Blood Moon' is often found in descriptions of such lunar events as far back as eclipses are recorded.

text: There are three types of lunar eclipses: penumbral, when the Moon crosses only the Earth's penumbra; partial, when the Moon crosses partially into the Earth's

text: umbra

text: ; and total, when the Moon crosses entirely into the Earth's umbra. Total lunar eclipses pass through all three phases. Even during a total lunar eclipse, however, the Moon is not completely dark. Sunlight refracted through the Earth's atmosphere enters the umbra and provides a faint illumination. Much as in a sunset, the atmosphere tends to more strongly scatter light with shorter wavelengths, so the illumination of the Moon by refracted light has a red hue, thus the phrase 'Blood Moon' is often found in descriptions of such lunar events as far back as eclipses are recorded.

text: Ole Christensen Rømer used an astronomical measurement to make the first quantitative estimate of the speed of light. When measured from Earth, the periods of moons orbiting a distant planet are shorter when the Earth is approaching the planet than when the Earth is receding from it. The distance travelled by light from the planet (or its moon) to Earth is shorter when the Earth is at the point in its orbit that is closest to its planet than when the Earth is at the farthest point in its orbit, the difference in distance being the diameter of the Earth's orbit around the Sun. The observed change in the moon's orbital period is caused by the difference in the time it takes light to traverse the shorter or longer distance. Rømer observed this effect for Jupiter's innermost moon Io and deduced that light takes 22 minutes to cross the diameter of the Earth's orbit.

text: Ole Christensen Rømer

text: used an astronomical measurement to make

text: the first quantitative estimate of the speed of light

text: . When measured from Earth, the periods of moons orbiting a distant planet are shorter when the Earth is approaching the planet than when the Earth is receding from it. The distance travelled by light from the planet (or its moon) to Earth is shorter when the Earth is at the point in its orbit that is closest to its planet than when the Earth is at the farthest point in its orbit, the difference in distance being the

text: diameter

text: of the Earth's orbit around the Sun. The observed change in the moon's orbital period is caused by the difference in the time it takes light to traverse the shorter or longer distance. Rømer observed this effect for

text: Jupiter

text: 's innermost moon

text: Io

text: and deduced that light takes 22 minutes to cross the diameter of the Earth's orbit.

text: Slocum is a small lunar impact crater in the southeastern part of the Mare Smythii. It lies near the eastern limb of the Moon, and from the Earth this section of the surface is viewed at a very oblique angle. This greatly limits the amount of detail that can be observed. In addition, libration of the Moon in its orbit can cause this area to be completely hidden from Earth. Nearby craters of note include Runge to the west-northwest, Warner to the west-southwest, and Swasey to the south-southeast.

text: Slocum is a small

text: lunar

text: impact crater

text: in the southeastern part of the

text: Mare Smythii

text: . It lies near the eastern limb of the

text: Moon

text: , and from the

text: Earth

text: this section of the surface is viewed at a very oblique angle. This greatly limits the amount of detail that can be observed. In addition,

text: libration

text: of the Moon in its orbit can cause this area to be completely hidden from Earth. Nearby craters of note include

text: Runge

text: to the west-northwest,

text: Warner

text: to the west-southwest, and

text: Swasey

text: to the south-southeast.

text: Macula (pl. maculae) is the Latin word for 'spot'. It is used in planetary nomenclature to refer to unusually dark areas on the surface of a planet or moon. They are seen on the icy surfaces of Pluto, Jupiter's moon Europa, Saturn's moon Titan, Neptune's moon Triton, and Pluto's moon Charon. The term was adopted for planetary nomenclature when high resolution pictures of Europa revealed unusual new surface features.

text: Macula (pl. maculae) is the

text: Latin

text: word for 'spot'. It is used in

text: planetary nomenclature

text: to refer to unusually dark areas on the surface of a

text: planet

text: or

text: moon

text: . They are seen on the icy surfaces of

text: Pluto

text: , Jupiter's moon

text: Europa

text: , Saturn's moon

text: Titan

text: , Neptune's moon

text: Triton

text: , and Pluto's moon

text: Charon

text: . The term was adopted for planetary nomenclature when high resolution pictures of Europa revealed unusual new surface features.

text: The tidal accelerations at the surfaces of planets in the Solar System are generally very small. For example, the lunar tidal acceleration at the Earth's surface along the Moon-Earth axis is about 1.1 × 10 g, while the solar tidal acceleration at the Earth's surface along the Sun-Earth axis is about 0.52 × 10 g, where g is the gravitational acceleration at the Earth's surface. Hence the tide-raising force (acceleration) due to the Sun is about 45% of that due to the Moon. The solar tidal acceleration at the Earth's surface was first given by Newton in the Principia.

text: The tidal accelerations at the surfaces of planets in the Solar System are generally very small. For example, the lunar tidal acceleration at the Earth's surface along the Moon-Earth axis is about 1.1 × 10 g, while the solar tidal acceleration at the Earth's surface along the Sun-Earth axis is about 0.52 × 10 g, where g is the

text: gravitational acceleration

text: at the Earth's surface. Hence the tide-raising force (acceleration) due to the Sun is about 45% of that due to the Moon. The solar tidal acceleration at the Earth's surface was first given by Newton in the

entity_name: Philosophiæ Naturalis Principia Mathematica

text: Principia

text: Although no other moons of Earth have been found to date, there are various types of near-Earth objects in 1:1 resonance with it, which are known as quasi-satellites. Quasi-satellites orbit the Sun from the same distance as a planet, rather than the planet itself. Their orbits are unstable, and will fall into other resonances or be kicked into other orbits over thousands of years. Quasi-satellites of Earth include , ,, , , , and 3753 Cruithne. Cruithne, discovered in 1986, orbits the Sun in an elliptical orbit but appears to have a horseshoe orbit when viewed from Earth. Some went as far to nickname Cruithne "Earth's second moon".

text: Although no other moons of Earth have been found to date, there are various types of

text: near-Earth objects

text: in 1:1 resonance with it, which are known as

text: quasi-satellite

text: s. Quasi-satellites orbit the Sun from the same distance as a planet, rather than the planet itself. Their orbits are unstable, and will fall into other resonances or be kicked into other orbits over thousands of years. Quasi-satellites of Earth include , ,, , , , and

text: 3753 Cruithne

text: . Cruithne, discovered in 1986, orbits the

text: Sun

text: in an elliptical orbit but appears to have a

text: horseshoe orbit

text: when viewed from Earth. Some went as far to nickname Cruithne "Earth's second moon".

text: When the Sun and Moon are aligned on the same side of the Earth, the moon is "new", and the side of the Moon facing Earth is not illuminated by the Sun. As the moon waxes (the amount of illuminated surface as seen from Earth is increasing), the lunar phases progress through new moon, crescent moon, first-quarter moon, gibbous moon, and full moon. The moon is then said to wane as it passes through the gibbous moon, third-quarter moon, crescent moon and back to new moon. The terms "old moon" and "new moon" are not interchangeable. The "old moon" is a waning sliver (which eventually becomes undetectable to the naked eye) until the moment it aligns with the sun and begins to wax, at which point it becomes new again. Half moon is often used to mean the first- and third-quarter moons, while the term 'quarter' refers to the extent of the moon's cycle around the Earth, not its shape.

text: When the Sun and Moon are aligned on the same side of the Earth, the moon is "new", and the side of the Moon facing Earth is not illuminated by the Sun. As the moon waxes (the amount of illuminated surface as seen from Earth is increasing), the lunar phases progress through new moon, crescent moon, first-quarter moon,

text: gibbous

text: moon, and full moon. The moon is then said to wane as it passes through the gibbous moon, third-quarter moon, crescent moon and back to new moon. The terms "old moon" and "new moon" are not interchangeable. The "old moon" is a waning sliver (which eventually becomes undetectable to the naked eye) until the moment it aligns with the sun and begins to wax, at which point it becomes new again. Half moon is often used to mean the first- and third-quarter moons, while the term 'quarter' refers to the extent of the moon's cycle around the Earth, not its shape.

text: Alternatively, his explanation may have involved the phenomenon of tides, which he supposedly theorized to be caused by the attraction to the Moon and by the revolution of the Earth around the Earth-Moon 'center of mass'.

text: Alternatively, his explanation may have involved the phenomenon of

text: tide

text: s, which he supposedly theorized to be caused by the attraction to the

text: Moon

text: and by the revolution of the

text: Earth

text: around the

text: Earth

text: Moon

text: 'center of mass'.

text: While gravitation causes acceleration and movement of the Earth's fluid oceans, gravitational coupling between the Moon and Earth's solid body is mostly elastic and plastic. The result is a further tidal effect of the Moon on the Earth that causes a bulge of the solid portion of the Earth nearest the Moon that acts as a torque in opposition to the Earth's rotation. This "drains" angular momentum and rotational kinetic energy from Earth's spin, slowing the Earth's rotation. That angular momentum, lost from the Earth, is transferred to the Moon in a process (confusingly known as tidal acceleration), which lifts the Moon into a higher orbit and results in its lower orbital speed about the Earth. Thus the distance between Earth and Moon is increasing, and the Earth's spin is slowing in reaction. Measurements from laser reflectors left during the Apollo missions (lunar ranging experiments) have found that the Moon's distance increases by  per year (roughly the rate at which human fingernails grow).Atomic clocks also show that Earth's day lengthens by about 15 microseconds every year, slowly increasing the rate at which UTC is adjusted by leap seconds.Left to run its course, this tidal drag would continue until the spin of Earth and the orbital period of the Moon matched, creating mutual tidal locking between the two. As a result, the Moon would be suspended in the sky over one meridian, as is already currently the case with Pluto and its moon Charon. However, the Sun will become a red giant engulfing the Earth-Moon system long before this occurrence.

text: While gravitation causes acceleration and movement of the Earth's fluid oceans, gravitational coupling between the Moon and Earth's solid body is mostly elastic and plastic. The result is a further tidal effect of the Moon on the Earth that causes a bulge of the solid portion of the Earth nearest the Moon that acts as a

text: torque

text: in opposition to the Earth's rotation. This "drains"

text: angular momentum

text: and rotational

text: kinetic energy

text: from Earth's spin, slowing the Earth's rotation. That angular momentum, lost from the Earth, is transferred to the Moon in a process (confusingly known as

text: tidal acceleration

text: ), which lifts the Moon into a higher orbit and results in its lower orbital speed about the Earth. Thus the distance between Earth and Moon is

text: increasing

text: , and the Earth's spin is slowing in reaction. Measurements from laser reflectors left during the Apollo missions (

text: lunar ranging experiments

text: ) have found that the Moon's distance increases by  per year (roughly the rate at which human fingernails grow).

text: Atomic clock

text: s also show that Earth's day lengthens by about 15

text: microsecond

text: s every year, slowly increasing the rate at which

text: UTC

text: is adjusted by

text: leap second

text: s.Left to run its course, this tidal drag would continue until the spin of Earth and the orbital period of the Moon matched, creating mutual tidal locking between the two. As a result, the Moon would be suspended in the sky over one meridian, as is already currently the case with

text: Pluto

text: and its moon

text: Charon

text: . However, the Sun will become a

text: red giant

text: engulfing the Earth-Moon system long before this occurrence.

text: The Earth and its Moon are one example of this configuration. Today, the Moon is tidally locked to the Earth; one of its revolutions around the Earth (currently about 29 days) is equal to one of its rotations about its axis, so it always shows one face to the Earth. The Moon will continue to recede from Earth, and Earth's spin will continue to slow gradually. In about 50 billion years, if they survive the Sun's expansion, the Earth and Moon will become tidally locked to each other; each will be caught up in what is called a "spin–orbit resonance" in which the Moon will circle the Earth in about 47 days and both Moon and Earth will rotate around their axes in the same time, each only visible from one hemisphere of the other. Other examples are the Galilean moons of Jupiter (as well as many of Jupiter's smaller moons) and most of the larger moons of Saturn.

text: The Earth and its Moon are one example of this configuration. Today, the Moon is

text: tidally locked

text: to the Earth; one of its revolutions around the Earth (currently about 29 days) is equal to one of its rotations about its axis, so it always shows one face to the Earth. The Moon will continue to recede from Earth, and Earth's spin will continue to slow gradually. In about 50 billion years, if they survive

entity_name: Formation and evolution of the Solar System

text: the Sun's expansion

text: , the Earth and Moon will become tidally locked to each other; each will be caught up in what is called a "spin–orbit resonance" in which the Moon will circle the Earth in about 47 days and both Moon and Earth will rotate around their axes in the same time, each only visible from one hemisphere of the other. Other examples are the

text: Galilean moons

text: of

text: Jupiter

text: (as well as many of Jupiter's smaller moons) and most of the larger moons of

text: Saturn

text: Bolyai is an old lunar crater that is located in the southern hemisphere on the far side of the Moon. To the southeast of Bolyai is the crater Eötvös, and to the north is Neujmin. It is named after the 19th century Hungarian mathematician János Bolyai.

text: Bolyai is an old

text: lunar

text: crater

text: that is located in the southern

text: hemisphere

text: on the

text: far side

text: of the

text: Moon

text: . To the southeast of Bolyai is the crater

text: Eötvös

text: , and to the north is

text: Neujmin

text: . It is named after the 19th century Hungarian mathematician

text: János Bolyai

text: Cosmic ray exposure history established with noble gas measurements have shown that all lunar meteorites were ejected from the Moon in the past 20 million years.  Most left the Moon in the past 100,000 years.  After leaving the Moon, most lunar meteoroids go into orbit around Earth and eventually succumb to Earth's gravity.  Some meteoroids ejected from the Moon get launched into orbits around the sun.  These meteoroids remain in space longer but eventually intersect the Earth's orbit and land.

text: Limited amateur radio operations have occurred, using moon bounce or Earth–Moon–Earth communication, in which radio signals aimed at the Moon are reflected back to Earth. The first of these operations was on June 13–14, 1964, using the call KP4BPZ. A dozen or so two-way contacts were made on 144 and 432 MHz. On July 3 and July 24, 1965, KP4BPZ was again activated on 432 MHz, making approximately 30 contacts on 432 MHz during the limited time slots available. For these tests, a very wide-band instrumentation recorder captured a large segment of the receiving bandwidth, enabling later verification of other amateur station callsigns. These were not two-way contacts. From April 16–18, 2010, again, the Arecibo Amateur Radio Club KP4AO conducted moon-bounce activity using the antenna.On November 10, 2013, the KP4AO Arecibo Amateur Radio Club conducted a Fifty-Year Commemoration Activation, lasting 7 hours on 14.250 MHz SSB, without using the main dish antenna.

text: Limited amateur radio operations have occurred, using moon bounce or

text: Earth–Moon–Earth communication

text: , in which radio signals aimed at the Moon are reflected back to Earth. The first of these operations was on June 13–14, 1964, using the call KP4BPZ. A dozen or so two-way contacts were made on 144 and 432 MHz. On July 3 and July 24, 1965, KP4BPZ was again activated on 432 MHz, making approximately 30 contacts on 432 MHz during the limited time slots available. For these tests, a very wide-band instrumentation recorder captured a large segment of the receiving bandwidth, enabling later verification of other amateur station callsigns. These were not two-way contacts. From April 16–18, 2010, again, the Arecibo Amateur Radio Club KP4AO conducted moon-bounce activity using the antenna.On November 10, 2013, the KP4AO Arecibo Amateur Radio Club conducted a Fifty-Year Commemoration Activation, lasting 7 hours on 14.250 MHz SSB, without using the main dish antenna.

text: The Lunar equatorial regions are likely to have higher concentrations of helium-3 (rare on Earth but much sought after for use in nuclear fusion research) because the solar wind has a higher angle of incidence. They also enjoy an advantage in extra-Lunar traffic: The rotation advantage for launching material is slight due to the Moon's slow rotation, but the corresponding orbit coincides with the ecliptic, nearly coincides with the Lunar orbit around Earth, and nearly coincides with the equatorial plane of Earth.

text: The Lunar equatorial regions are likely to have higher concentrations of

text: (rare on Earth but much sought after for use in nuclear fusion research) because the

text: solar wind

text: has a higher

text: angle of incidence

text: . They also enjoy an advantage in extra-Lunar traffic: The rotation advantage for launching material is slight due to the Moon's slow rotation, but the corresponding orbit coincides with the ecliptic, nearly coincides with the Lunar orbit around Earth, and nearly coincides with the equatorial plane of Earth.

text: Michener dramatizes the life experiences of these men and their families against the backdrop of the real history of the U.S. space program, depicting their experiences in post-war aviation; the space race between the United States and the Soviet Union; the development of congressional funding for the space program; the early failures in the Gemini program; and the successful moon landings in the Apollo program. In a fictional postscript to history, Michener creates a last, "Apollo 18" launch to further the drama of Pope, Claggett and Linley, America's first black astronaut. This is the only Apollo mission in which the lunar module lands on the far side of the Moon; in order to remain in contact with NASA after landing, while still in lunar orbit the Apollo craft must launch communication satellites that will bounce the lunar module's signals to Earth. An exceptional and unexpected burst of sunspot activity results in the death of Claggett and Linley: the two astronauts are exposed to a lethal level of radiation while out on the lunar surface during a large solar flare. After hastily returning to the Lunar Module, Linley loses consciousness and Claggett attempts an emergency ascent back towards the command module. However he also loses consciousness, and the Lunar Module crashes back onto the lunar surface. Pope, the command module pilot, returns to Earth safely. The mission profile is significantly different from that of the real-world canceled mission that would have been Apollo 18.

text: Michener dramatizes the life experiences of these men and their families against the backdrop of the real history of the U.S. space program, depicting their experiences in post-war aviation; the

text: space race

text: between the United States and the Soviet Union; the development of congressional funding for the space program; the early failures in the

text: Gemini program

text: ; and the successful moon landings in the

text: Apollo program

text: . In a fictional postscript to history, Michener creates a last, "Apollo 18" launch to further the drama of Pope, Claggett and Linley, America's first black astronaut. This is the only Apollo mission in which the lunar module lands on the

text: far side of the Moon

text: ; in order to remain in contact with NASA after landing, while still in lunar orbit the Apollo craft must launch communication satellites that will bounce the lunar module's signals to Earth. An exceptional and unexpected burst of sunspot activity results in the death of Claggett and Linley: the two astronauts are exposed to a lethal level of radiation while out on the lunar surface during a large

text: solar flare

text: . After hastily returning to the Lunar Module, Linley loses consciousness and Claggett attempts an emergency ascent back towards the command module. However he also loses consciousness, and the Lunar Module crashes back onto the lunar surface. Pope, the command module pilot, returns to Earth safely. The mission profile is significantly different from that of the real-world canceled mission that would have been

text: Apollo 18

text: The Earth, Moon, and some other bodies have, to some extent, the property of retroreflection. Light which strikes them is reflected preferentially back in the direction from which it has come, rather than in other directions. If the light comes from the Sun, it is reflected back toward the Sun and in nearby directions. For example, when its phase is full, the Moon reflects light preferentially toward the Sun, and toward the Earth, which is in almost the same direction. The full Moon therefore appears brighter, when seen from Earth, than it would if it diffused light uniformly in all directions. Similarly, near new moon, earthshine which has been retroreflected by the Earth toward the Sun, or toward the Moon which is in almost the same direction, and then retroreflected again by the Moon toward the Earth appears much brighter, seen from Earth, than it would without the retroreflective effects. The retroreflection is produced by spheres of transparent material on the reflecting surface. When it encounters a transparent sphere, light is preferentially reflected and refracted in a path, within the sphere, which exits it in the direction from which it entered. On the Earth, the spheres are droplets of water in clouds. On the Moon, large numbers of solid glassy spheres are found on the surface. They are thought to have been formed from drops of molten rock, produced by impacts, which cooled and solidified before falling back to the surface.

text: The

text: Earth

text: Moon

text: , and some other bodies have, to some extent, the property of

text: retroreflection

text: . Light which strikes them is reflected preferentially back in the direction from which it has come, rather than in other directions. If the light comes from the Sun, it is reflected back toward the Sun and in nearby directions. For example, when its

text: phase

text: is full, the Moon reflects light preferentially toward the Sun, and toward the Earth, which is in almost the same direction. The full Moon therefore appears brighter, when seen from Earth, than it would if it diffused light uniformly in all directions. Similarly, near new moon, earthshine which has been retroreflected by the Earth toward the Sun, or toward the Moon which is in almost the same direction, and then retroreflected again by the Moon toward the Earth appears much brighter, seen from Earth, than it would without the retroreflective effects. The retroreflection is produced by spheres of transparent material on the reflecting surface. When it encounters a transparent sphere, light is preferentially reflected and refracted in a path, within the sphere, which exits it in the direction from which it entered. On the Earth, the spheres are droplets of water in clouds. On the Moon, large numbers of solid glassy spheres are found on the surface. They are thought to have been formed from drops of molten rock, produced by impacts, which cooled and solidified before falling back to the surface.

text: The relative age and nature of intercrater plains material are as uncertain in the Borealis region as they are elsewhere on Mercury. Strom noted the similarity in surficial morphologies between mercurian intercrater plains and pre-Imbrian pitted plains south-southwest of Mare Nectaris on the Moon (Wilhelms and McCauley, 1971; Scott, 1972). The pits in the lunar pre-Imbrian pitted plains are similar to the small secondaries that pepper the surface of Mercurian intercrater plains material. On the Moon, pre-Imbrian pitted plains material embays the Janssen Formation (Scott, 1972), whose base is defined as the base of the Nectarian System (Stuart-Alexander and Wilhelms, 1975). However, the crater density of the intercrater plains material in the Borealis region matches that of an area on the far side of the Moon, in the region northwest of crater Tsiolkovskiy bounded by crater Mendeleev and Mare Smithii. This area is dominated by pre-Nectarian unmantled terra and pre-Nectarian and Nectarian craters (Wilhelms and El- Baz, 1977). The similarity in crater density of intercrater plains material on Mercury and of pre-Nectarian terrain on the Moon is geologically significant, inasmuch as it shows that the oldest recognizable surfaces on both Mercury and the Moon went through similar stages of crustal cratering, but not necessarily at the same absolute geologic time. Differences in crater density as well as embayment relations in the Borealis region show that the intercrater plains material and the smoother intermediate plains material are younger than many craters in the area northeast of crater Turgenev, and older than smooth plains material in Borealis Planitia.

text: The relative age and nature of intercrater plains material are as uncertain in the Borealis region as they are elsewhere on Mercury. Strom noted the similarity in surficial morphologies between mercurian intercrater plains and pre-

text: Imbrian

text: pitted plains south-southwest of

text: Mare Nectaris

text: on the Moon (Wilhelms and McCauley, 1971; Scott, 1972). The pits in the lunar pre-Imbrian pitted plains are similar to the small secondaries that pepper the surface of Mercurian intercrater plains material. On the Moon, pre-Imbrian pitted plains material embays the

text: Janssen Formation

text: (Scott, 1972), whose base is defined as the base of the

text: Nectarian System

text: (Stuart-Alexander and Wilhelms, 1975). However, the crater density of the intercrater plains material in the Borealis region matches that of an area on the far side of the Moon, in the region northwest of crater

text: Tsiolkovskiy

text: bounded by crater

text: Mendeleev

text: and

text: Mare Smithii

text: . This area is dominated by

text: pre-Nectarian

text: unmantled terra and pre-Nectarian and

text: Nectarian

text: craters (Wilhelms and El- Baz, 1977). The similarity in crater density of intercrater plains material on Mercury and of pre-Nectarian terrain on the Moon is geologically significant, inasmuch as it shows that the oldest recognizable surfaces on both Mercury and the Moon went through similar stages of crustal cratering, but not necessarily at the same absolute geologic time. Differences in crater density as well as embayment relations in the Borealis region show that the intercrater plains material and the smoother intermediate plains material are younger than many craters in the area northeast of crater

text: Turgenev

text: , and older than smooth plains material in Borealis Planitia.

text: The  point, on the far side of the Moon, is completely shielded from Earth by the Moon so radio telescopes placed there would receive much less interference than existing telescopes. Of course, since the Moon is tidally locked, any colony on the far side of the Moon has this same benefit; a lunar facility, however, would suffer from Moonquakes

text: The  point, on the

text: far side of the Moon

text: , is completely shielded from Earth by the Moon so

text: radio telescope

text: s placed there would receive much less interference than existing telescopes. Of course, since the Moon is

text: tidally locked

text: , any colony on the

text: far side of the Moon

text: has this same benefit; a lunar facility, however, would suffer from

text: Moonquake

text: s

text: Lunar Prospector was the third mission selected by NASA for full development and construction as part of the Discovery Program. At a cost of $62.8 million, the 19-month mission was put into a low polar orbit of the Moon, accomplishing mapping of surface composition and possible polar ice deposits, measurements of magnetic and gravity fields, and study of lunar outgassing events. Based on Lunar Prospector Neutron Spectrometer (NS) data, mission scientists have determined that there is indeed water ice in the polar craters of the Moon. The mission ended July 31, 1999 when the orbiter was guided to an impact into a crater near the lunar south pole in an (unsuccessful) attempt to analyze lunar polar water by vaporizing it to allow spectroscopic characterization from Earth telescopes.

text: Lunar Prospector

text: was the third mission selected by NASA for full development and construction as part of the

text: Discovery Program

text: . At a cost of $62.8 million, the 19-month mission was put into a low polar orbit of the Moon, accomplishing mapping of surface composition and possible polar ice deposits, measurements of magnetic and gravity fields, and study of lunar outgassing events. Based on Lunar Prospector Neutron Spectrometer (NS) data, mission scientists have determined that there is indeed

text: water ice

text: in the polar craters of the Moon. The mission ended July 31, 1999 when the orbiter was guided to an impact into a crater near the lunar south pole in an (unsuccessful) attempt to analyze lunar polar water by vaporizing it to allow spectroscopic characterization from Earth telescopes.

text: A penumbral eclipse occurs when the moon passes through the Earth's penumbra. The penumbra causes a subtle darkening of the moon's surface. A special type of penumbral eclipse is a total penumbral eclipse, during which the Moon lies exclusively within the Earth's penumbra. Total penumbral eclipses are rare, and when these occur, that portion of the moon which is closest to the umbra can appear somewhat darker than the rest of the moon.

text: A penumbral eclipse occurs when the moon passes through the Earth's penumbra. The penumbra causes a subtle darkening of the moon's surface. A special type of penumbral eclipse is a

text: total penumbral eclipse

text: , during which the Moon lies exclusively within the Earth's penumbra. Total penumbral eclipses are rare, and when these occur, that portion of the moon which is closest to the umbra can appear somewhat darker than the rest of the moon.

text: A partial solar eclipse occurred on September 10, 1942. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on September 10, 1942. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Early attempts to measure the distance to the Moon exploited observations of a lunar eclipse combined with knowledge of Earth's radius and an understanding that the Sun is much further than the Moon. By observing the geometry of a lunar eclipse, the lunar distance can be calculated using trigonometry.

text: Early attempts to measure the distance to the Moon exploited observations of a

text: lunar eclipse

text: combined with knowledge of Earth's radius and an understanding that the Sun is much further than the Moon. By observing the geometry of a

text: lunar eclipse

text: , the lunar distance can be calculated using

text: trigonometry

text: It is possible to aim a spacecraft from Earth so that it will loop around the Moon and return to Earth without entering lunar orbit, following the so-called free return trajectory. Such circumlunar loop missions are simpler than lunar orbit missions because rockets for lunar orbit braking and Earth return are not required. However, a manned circumlunar loop trip poses significant challenges above and beyond those found in a manned low-Earth-orbit mission, offering valuable lessons in preparation for a manned Moon landing. Foremost among these are mastering the demands of re-entering the Earth's atmosphere upon returning from the Moon.

text: It is possible to aim a spacecraft from Earth so that it will loop around the Moon and return to Earth without entering lunar orbit, following the so-called

text: free return trajectory

text: . Such circumlunar loop missions are simpler than lunar orbit missions because rockets for lunar orbit braking and Earth return are not required. However, a manned circumlunar loop trip poses significant challenges above and beyond those found in a manned low-Earth-orbit mission, offering valuable lessons in preparation for a manned Moon landing. Foremost among these are mastering the demands of re-entering the Earth's atmosphere upon returning from the Moon.

text: Because the Moon's orbit around Earth is inclined by about 5° to the orbit of Earth around the Sun, eclipses do not occur at every full and new moon. For an eclipse to occur, the Moon must be near the intersection of the two orbital planes. The periodicity and recurrence of eclipses of the Sun by the Moon, and of the Moon by Earth, is described by the saros, which has a period of approximately 18 years.

text: Because the Moon's orbit around Earth is inclined by about 5° to the

text: orbit of Earth around the Sun

text: , eclipses do not occur at every full and new moon. For an eclipse to occur, the Moon must be near the intersection of the two orbital planes. The periodicity and recurrence of eclipses of the Sun by the Moon, and of the Moon by Earth, is described by the

text: saros

text: , which has a period of approximately 18 years.

text: Other mechanisms that have been suggested at various times for the Moon's origin are that the Moon was spun off from the Earth's molten surface by centrifugal force; that it was formed elsewhere and was subsequently captured by the Earth's gravitational field; or that the Earth and the Moon formed at the same time and place from the same accretion disk. None of these hypotheses can account for the high angular momentum of the Earth–Moon system.

text: Other mechanisms that have been suggested at various times for the Moon's origin are that the Moon was spun off from the Earth's molten surface by

text: centrifugal force

text: ; that it was formed elsewhere and was subsequently

text: captured

text: by the Earth's gravitational field; or that the Earth and the Moon formed at the same time and place from the same

text: accretion disk

text: . None of these hypotheses can account for the high

text: angular momentum

text: of the Earth–Moon system.

text: Lorentz is a huge lunar crater that lies just beyond the northwest limb of the Moon, in a region that is brought into sight of the Earth during favorable librations. This formation is nearly as large as the Mare Nectaris on the near side of the Moon, although it has not been submerged by lava as have the lunar mare. Sections of the crater floor are, however, relatively level, particularly an arc along the western rim. But this last region is still marked by a number of tiny craterlets. The remainder of the interior is rough and irregular, and marked with a multitude of impacts.

text: Lorentz is a huge

text: lunar

text: crater

text: that lies just beyond the northwest limb of the

text: Moon

text: , in a region that is brought into sight of the

text: Earth

text: during favorable

text: libration

text: s. This formation is nearly as large as the

text: Mare Nectaris

text: on the near side of the Moon, although it has not been submerged by

text: lava

text: as have the

text: lunar mare

text: . Sections of the crater floor are, however, relatively level, particularly an arc along the western rim. But this last region is still marked by a number of tiny craterlets. The remainder of the interior is rough and irregular, and marked with a multitude of impacts.

text: The cratered terrain, a rolling surface covered by numerous impact craters and centered on Ariel's south pole, is the moon's oldest and most geographically extensive geological unit. It is intersected by a network of scarps, canyons (graben), and narrow ridges mainly occurring in Ariel's mid-southern latitudes. The canyons, known as chasmata, probably represent graben formed by extensional faulting, which resulted from global tensional stresses caused by the freezing of water (or aqueous ammonia) in the moon's interior (see below). They are 15–50 km wide and trend mainly in an east- or northeasterly direction. The floors of many canyons are convex; rising up by 1–2 km. Sometimes the floors are separated from the walls of canyons by grooves (troughs) about 1 km wide. The widest graben have grooves running along the crests of their convex floors, which are called valles. The longest canyon is Kachina Chasma, at over 620 km in length (the feature extends into the hemisphere of Ariel that Voyager 2 did not see illuminated).

text: The cratered terrain, a rolling surface covered by numerous impact craters and centered on Ariel's south pole, is the moon's oldest and most geographically extensive

text: geological unit

text: . It is intersected by a network of scarps, canyons (graben), and narrow ridges mainly occurring in Ariel's mid-southern latitudes. The canyons, known as

text: chasmata

text: , probably represent

text: graben

text: formed by

text: extensional fault

text: ing, which resulted from global tensional stresses caused by the freezing of water (or aqueous ammonia) in the moon's interior (see below). They are 15–50 km wide and trend mainly in an east- or northeasterly direction. The floors of many canyons are convex; rising up by 1–2 km. Sometimes the floors are separated from the walls of canyons by grooves (troughs) about 1 km wide. The widest graben have grooves running along the crests of their convex floors, which are called

text: valles

text: . The longest canyon is

text: Kachina Chasma

text: , at over 620 km in length (the feature extends into the hemisphere of Ariel that Voyager 2 did not see illuminated).

text: Han-era astronomers adopted a geocentric model of the universe, theorizing that it was shaped like a sphere surrounding the earth in the center. They assumed that the Sun, Moon, and planets were spherical and not disc-shaped. They also thought that the illumination of the Moon and planets was caused by sunlight, that lunar eclipses occurred when the Earth obstructed sunlight falling onto the Moon, and that a solar eclipse occurred when the Moon obstructed sunlight from reaching the Earth. Although others disagreed with his model, Wang Chong accurately described the water cycle of the evaporation of water into clouds.

text: Han-era astronomers adopted a

text: geocentric model

text: of the universe, theorizing that it was

text: shaped like a sphere

text: surrounding the earth in the center. They assumed that the Sun, Moon, and planets were spherical and not disc-shaped. They also thought that the illumination of the Moon and planets was caused by

text: sunlight

text: , that

text: lunar eclipse

text: s occurred when the Earth obstructed sunlight falling onto the Moon, and that a

text: solar eclipse

text: occurred when the Moon obstructed sunlight from reaching the Earth. Although others disagreed with his model, Wang Chong accurately described the

text: water cycle

text: of the

text: evaporation

text: of water into clouds.

text: A partial solar eclipse will occur on January 6, 2019. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on January 6, 2019. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The gravitational attraction that masses have for one another decreases inversely with the square of the distance of those masses from each other. As a result, the slightly greater attraction that the Moon has for the side of Earth closest to the Moon, as compared to the part of the Earth opposite the Moon, results in tidal forces. Tidal forces affect both the Earth's crust and oceans.

text: The gravitational attraction that masses have for one another decreases inversely with the square of the distance of those masses from each other. As a result, the slightly greater attraction that the Moon has for the side of Earth closest to the Moon, as compared to the part of the Earth opposite the Moon, results in

text: tidal forces

text: . Tidal forces affect both the Earth's crust and oceans.

text: A total solar eclipse will occur on September 3, 2081. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on September 3, 2081. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Baltimore, in the northern portion of the Bay, experiences a noticeable modulation to form its mixed tidal nature during spring vs. neap tides.  Spring tides, when the sun-earth-moon system forms a line, cause the largest tidal amplitudes during lunar monthly tidal variations.  In contrast, neap tides, when the sun-earth-moon system forms a right angle, are muted, and in a semi-diurnal tidal system (such as that seen at the CBBT site) this can be seen as a lowest intertidal range.

text: A study in 2012 evaluated South Africa's bucket eradication programme and highlighted the following weaknesses: "One-size-fits-all" toilets were constructed that did not meet the special sanitation needs of vulnerable groups; health and hygiene education and user education had not been integrated; community participation barely took place; and operation and maintenance of water treatment works were neglected, as were water conservation and water demand management.

text: An example of a body in a tadpole orbit is Polydeuces, a small moon of Saturn which librates around the trailing  point relative to a larger moon, Dione. In relation to the orbit of Earth, the 300-meter-diameter asteroid  is in a tadpole orbit around the leading  point.

text: An example of a body in a tadpole orbit is

text: Polydeuces

text: , a small moon of

text: Saturn

text: which librates around the trailing  point relative to a larger moon,

text: Dione

text: . In relation to the orbit of Earth, the 300-meter-diameter asteroid  is in a tadpole orbit around the leading  point.

text: Blanketed on top of the Moon's crust is a highly comminuted (broken into ever smaller particles) and impact gardened surface layer called regolith, formed by impact processes. The finer regolith, the lunar soil of silicon dioxide glass, has a texture resembling snow and a scent resembling spent gunpowder. The regolith of older surfaces is generally thicker than for younger surfaces: it varies in thickness from  in the highlands and  in the maria.Beneath the finely comminuted regolith layer is the megaregolith, a layer of highly fractured bedrock many kilometres thick.

text: Blanketed on top of the Moon's crust is a highly

text: comminuted

text: (broken into ever smaller particles) and

text: impact gardened

text: surface layer called

text: regolith

text: , formed by impact processes. The finer regolith, the

text: lunar soil

text: of

text: silicon dioxide

text: glass, has a texture resembling snow and a scent resembling spent

text: gunpowder

text: . The regolith of older surfaces is generally thicker than for younger surfaces: it varies in thickness from  in the highlands and  in the maria.Beneath the finely comminuted regolith layer is the megaregolith, a layer of highly fractured bedrock many kilometres thick.

text: In 2006, NASA reported that Cassini had found evidence of liquid water reservoirs that erupt in geysers on Saturn's moon Enceladus. Images had shown jets of icy particles being emitted into orbit around Saturn from vents in the moon's south polar region. According to Andrew Ingersoll, California Institute of Technology, "Other moons in the Solar System have liquid-water oceans covered by kilometers of icy crust. What's different here is that pockets of liquid water may be no more than tens of meters below the surface." Over 100 geysers have been identified on Enceladus. In May 2011, NASA scientists at an Enceladus Focus Group Conference reported that Enceladus "is emerging as the most habitable spot beyond Earth in the Solar System for life as we know it".

text: In 2006, NASA reported that Cassini had found evidence of liquid water reservoirs that erupt in

text: geyser

text: s on Saturn's moon

text: Enceladus

text: . Images had shown jets of icy particles being emitted into orbit around Saturn from vents in the moon's south polar region. According to Andrew Ingersoll, California Institute of Technology, "Other moons in the Solar System have liquid-water oceans covered by kilometers of icy crust. What's different here is that pockets of liquid water may be no more than tens of meters below the surface." Over 100 geysers have been identified on Enceladus. In May 2011, NASA scientists at an Enceladus Focus Group Conference reported that Enceladus "is emerging as the most habitable spot beyond Earth in the Solar System for life as we know it".

text: When viewed from the north celestial pole, i.e. from the approximate direction of the star Polaris, the Moon orbits Earth anticlockwise and Earth orbits the Sun anticlockwise, and the Moon and Earth rotate on their own axes anticlockwise.

text: When viewed from the north

text: celestial pole

text: , i.e. from the approximate direction of the star

text: Polaris

text: , the Moon orbits Earth

text: anticlockwise

text: and Earth orbits the Sun anticlockwise, and the Moon and Earth rotate on their own axes anticlockwise.

text: Ansgarius is a lunar impact crater that is located near the eastern limb of the Moon. When viewed from the Earth, the crater has a highly oval shape due to foreshortening, but the rim is actually nearly circular. To the northwest of Ansgarius is the crater La Pérouse, and south is Behaim.

text: Ansgarius is a

text: lunar

text: impact crater

text: Moon

text: . When viewed from the

text: Earth

text: , the crater has a highly oval shape due to foreshortening, but the rim is actually nearly circular. To the northwest of Ansgarius is the crater

text: La Pérouse

text: , and south is

text: Behaim

text: The 20th century brought more advances to study of the Moon. In 1959, Russia's Luna 3 sent back the first photographs of the far side of the Moon, giving the world the first glimpse of the until-then unseen side of our satellite. The United States launched the Ranger spacecraft between 1961 and 1965 to take photographs right down to the instant they impacted the surface, the Lunar Orbiters between 1966 and 1967 to photograph the Moon from orbit, and the Surveyors between 1966 and 1968 to take photos and soft land on the lunar surface. The Russian Lunokhods 1 (1970) and 2 (1973) traversed almost 50 km of the lunar surface, obtaining detailed images of the lunar surface. The Clementine spacecraft obtained the first near global map of the Moon's topography, as well as multispectral images. All of these missions sent back photographs that were of increasingly better resolution.

text: The 20th century brought more advances to study of the Moon. In 1959, Russia's

text: Luna 3

text: sent back the first photographs of the

text: far side of the Moon

text: , giving the world the first glimpse of the until-then unseen side of our

text: satellite

text: . The United States launched the

text: Ranger

text: spacecraft between 1961 and 1965 to take photographs right down to the instant they impacted the surface, the

text: Lunar Orbiter

text: s between 1966 and 1967 to photograph the Moon from orbit, and the

text: Surveyors

text: between 1966 and 1968 to take photos and soft land on the lunar surface. The Russian

text: Lunokhod

text: s

text: (1970) and

text: (1973) traversed almost 50 km of the lunar surface, obtaining detailed images of the lunar surface. The

text: Clementine

text: spacecraft obtained the first near global map of the Moon's topography, as well as multispectral images. All of these missions sent back photographs that were of increasingly better resolution.

text: A total solar eclipse occurred on October 2, 1959. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on October 2, 1959. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: According to an article in the Guardian, in 2005, deputy minister Qiu Baoxing stated that more than 100 out of the 660 cities had extreme water shortages. Pan Yue, deputy director of the state environment protection agency, warned that economic growth was unsustainable due to the water problems. In 2004 the World Bank warned  that the scarcity of the resource would lead to "a fight between rural interests, urban interests and industrial interests on who gets water in China." In April 2005 there were dozens of injuries in Dongyang city, Zhejiang Province, due to clashes over the nearby chemical factories of the Juxi Industrial Park accused of water pollution that harmed crops and led to deformed babies being born. According to the article, a quarter of the population lacked clean drinking water and less than a third of the waste was treated. China is expected to face worsening water shortages until 2030 when the population peaks.

text: According to an article in the Guardian, in 2005, deputy minister Qiu Baoxing stated that more than 100 out of the 660 cities had extreme water shortages. Pan Yue, deputy director of the state environment protection agency, warned that economic growth was unsustainable due to the water problems. In 2004 the

text: World Bank

text: warned  that the scarcity of the resource would lead to "a fight between rural interests, urban interests and industrial interests on who gets water in China." In April 2005 there were dozens of injuries in

text: Dongyang

text: city,

text: Zhejiang Province

text: , due to clashes over the nearby chemical factories of the Juxi Industrial Park accused of water pollution that harmed crops and led to deformed babies being born. According to the article, a quarter of the population lacked clean drinking water and less than a third of the waste was treated. China is expected to face worsening water shortages until 2030 when the population peaks.

text: A total solar eclipse occurred on November 30, 1853. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on November 30, 1853. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Sinus Iridum (Latin for "Bay of Rainbows") is a plain of basaltic lava that forms a northwestern extension to the Mare Imbrium on Earth's moon. It is surrounded from the northeast to the southwest by the Montes Jura range. The protruding part of the range at the southwest end is named Promontorium Heraclides, while that at the northeast end is called Promontorium Laplace. This bay and the surrounding mountains is considered one of the most beautiful features on the Moon, and is a favorite among lunar observers.

text: Sinus Iridum (

text: Latin

text: for "Bay of Rainbows") is a plain of

text: basalt

text: ic

text: lava

text: that forms a northwestern extension to the

text: Mare Imbrium

text: on Earth's moon. It is surrounded from the northeast to the southwest by the

text: Montes Jura

text: range. The protruding part of the range at the southwest end is named

text: Promontorium Heraclides

text: , while that at the northeast end is called

text: Promontorium Laplace

text: . This bay and the surrounding mountains is considered one of the most beautiful features on the Moon, and is a favorite among lunar observers.

text: ); thus, the orbital parameters of the planets are given in heliocentric terms. The difference between the primocentric and "absolute" orbits may best be illustrated by looking at the Earth–Moon system. The mass ratio in this case is . The Earth–Moon characteristic distance, the semi-major axis of the geocentric lunar orbit, is 384,400 km. The barycentric lunar orbit, on the other hand, has a semi-major axis of 379,700 km, the Earth's counter-orbit taking up the difference, 4,700 km. The Moon's average barycentric orbital speed is 1.010 km/s, whilst the Earth's is 0.012 km/s. The total of these speeds gives a geocentric lunar average orbital speed of 1.022 km/s; the same value may be obtained by considering just the geocentric semi-major axis value.

text: The dark and relatively featureless lunar plains, clearly be seen with the naked eye, are called maria (Latin for "seas"; singular mare), as they were once believed to be filled with water; they are now known to be vast solidified pools of ancient basaltic lava. Although similar to terrestrial basalts, lunar basalts have more iron and no minerals altered by water. The majority of these lavas erupted or flowed into the depressions associated with impact basins. Several geologic provinces containing shield volcanoes and volcanic domes are found within the near side "maria".

text: The dark and relatively featureless lunar plains, clearly be seen with the naked eye, are called

text: maria

text: Latin

text: for "seas"; singular mare), as they were once believed to be filled with water; they are now known to be vast solidified pools of ancient

text: basalt

text: ic lava. Although similar to terrestrial basalts, lunar basalts have more iron and no minerals altered by water. The majority of these lavas erupted or flowed into the depressions associated with

text: impact basins

text: . Several

text: geologic province

text: s containing

text: shield volcano

text: es and volcanic

text: domes

text: are found within the near side "maria".

text: If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same orbital plane, there would be total solar eclipses every month. However, the Moon's orbit is inclined (tilted) at more than 5 degrees to the Earth's orbit around the Sun (see ecliptic), so its shadow at new moon usually misses Earth. Earth's orbit is called the ecliptic plane as the Moon's orbit must cross this plane in order for an eclipse (both solar as well as lunar) to occur. In addition, the Moon's actual orbit is elliptical, often taking it far enough away from Earth that its apparent size is not large enough to block the Sun totally. The orbital planes cross each other at a line of nodes resulting in at least two, and up to five, solar eclipses occurring each year; no more than two of which can be total eclipses. However, total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's shadow or umbra.

text: If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same

text: orbital plane

text: , there would be total solar eclipses every month. However, the Moon's orbit is

text: inclined

text: (tilted) at more than 5 degrees to the Earth's orbit around the Sun (see

text: ecliptic

text: ), so its shadow at new moon usually misses Earth. Earth's orbit is called the ecliptic plane as the Moon's orbit must cross this plane in order for an eclipse (both solar as well as

text: lunar

text: ) to occur. In addition, the Moon's actual orbit is elliptical, often taking it far enough away from Earth that its

text: apparent size

text: is not large enough to block the Sun totally. The orbital planes cross each other at a

text: line of nodes

text: resulting in at least two, and up to five, solar eclipses occurring each year; no more than two of which can be total eclipses. However, total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's shadow or

text: umbra

text: The Aristotelian explanation of gravity is that all bodies move toward their natural place. For the elements earth and water, that place is the center of the (geocentric) universe; the natural place of water is a concentric shell around the earth because earth is heavier; it sinks in water. The natural place of air is likewise a concentric shell surrounding that of water; bubbles rise in water. Finally, the natural place of fire is higher than that of air but below the innermost celestial sphere (carrying the Moon).

text: The Aristotelian explanation of gravity is that all bodies move toward their natural place. For the elements earth and water, that place is the center of the (

text: geocentric

text: ) universe; the natural place of water is a concentric shell around the earth because earth is heavier; it sinks in water. The natural place of air is likewise a concentric shell surrounding that of water; bubbles rise in water. Finally, the natural place of fire is higher than that of air but below the innermost celestial sphere (carrying the Moon).

text: Most lunar meteorites are launched from the Moon by impacts making lunar craters of a few kilometers in diameter or less.   No source crater of lunar meteorites has been positively identified, although there is speculation that the highly anomalous lunar meteorite Sayh al Uhaymir 169 derives from the Lalande impact crater on the lunar nearside.

text: Most lunar meteorites are launched from the Moon by impacts making lunar craters of a few kilometers in diameter or less.   No source crater of lunar meteorites has been positively identified, although there is speculation that the highly anomalous lunar meteorite

text: Sayh al Uhaymir 169

text: derives from the

text: Lalande

text: impact crater on the lunar nearside.

text: Sklodowska (Skłodowska) is a large lunar impact crater that is located on the far side of the Moon. It lies just past the southeastern limb, and can sometimes be viewed from Earth under favorable conditions of libration and illumination. The crater is located to the northeast of the older walled plain Curie, and to the southwest of Pasteur, another walled plain.

text: Sklodowska (Skłodowska) is a large

text: lunar

text: impact crater

text: that is located on the

text: far side

text: of the

text: Moon

text: . It lies just past the southeastern limb, and can sometimes be viewed from

text: Earth

text: under favorable conditions of

text: libration

text: and illumination. The crater is located to the northeast of the older walled plain

text: Curie

text: , and to the southwest of

text: Pasteur

text: , another walled plain.

text: At a laboratory at Camp Evans (part of Fort Monmouth), in Wall Township, New Jersey, a large transmitter, receiver and antenna array were constructed for this purpose. The transmitter, a highly modified SCR-271 radar set from World War II,  provided 3 kilowatts (later upgraded to 50 kilowatts) at 111.5 MHz in -second pulses, applied to the  antenna, a "bedspring" reflective array antenna composed of an 8x8 array of half wave dipoles in front of a reflector which provided 24 dB of gain. Reflected signals were received about 2.5 seconds later, the time required for the radio waves to make the  round-trip journey from the Earth to the Moon and back.  The receiver had to compensate for the Doppler shift in frequency of the reflected signal due to the Moon's orbital motion relative to the Earth's surface, which was different each day, so this motion had to be carefully calculated for each trial.   The antenna could be rotated in azimuth only, so the attempt could be made only as the moon passed through the 15 degree wide beam at moonrise and moonset, as the antenna's elevation angle was horizontal. About 40 minutes of observation was available on each pass as the Moon transited the various lobes of the antenna pattern.

text: At a laboratory at

text: Camp Evans

text: (part of

text: Fort Monmouth

text: ), in

text: Wall Township, New Jersey

text: , a large

text: transmitter

text: receiver

text: and

text: antenna array

text: were constructed for this purpose. The transmitter, a highly modified SCR-271

text: radar

text: set from

text: World War II

text: ,  provided 3

text: kilowatt

text: s (later upgraded to 50 kilowatts) at 111.5

text: MHz

text: in -second pulses, applied to the  antenna, a "bedspring"

text: reflective array antenna

text: composed of an 8x8 array of

text: half wave dipole

text: s in front of a reflector which provided 24

text: dB

text: of gain. Reflected signals were received about 2.5 seconds later, the time required for the radio waves to make the  round-trip journey from the Earth to the Moon and back.  The receiver had to compensate for the

text: Doppler shift

text: in frequency of the reflected signal due to the Moon's orbital motion relative to the Earth's surface, which was different each day, so this motion had to be carefully calculated for each trial.   The antenna could be rotated in

text: azimuth

text: only, so the attempt could be made only as the moon passed through the 15 degree wide beam at moonrise and moonset, as the antenna's

text: elevation

text: angle was horizontal. About 40 minutes of observation was available on each pass as the Moon transited the various lobes of the

text: antenna pattern

text: During the sequence where Amy attempts to retrieve the keys for the Planet Express Ship from the vending machine, an arcade game titled Gender-Neutral Pac-Person can be seen in the background, a reference to the Namco arcade games Pac-Man and Ms. Pac-Man.Also, The Goophy Gopher Revue is said to have been sponsored by Monsanto, a bioengineering conglomerate from the United States. Crater Face, the Lunar Park mascot, is a reference to the moon from the 1902 French silent film A Trip to the Moon. Bender impales Crater Face in the eye with his beer bottle after Crater Face attempts to confiscate his alcohol, which is another reference to the film as the astronomers' capsule (which resembles a bottle) hitting the moon's eye when it crashes. The title of the episode itself is a reference to the quote "The Eagle has landed" said by astronaut Neil Armstrong when he and Buzz Aldrin touched down on the Moon during the Apollo 11 mission. Fry nearly makes a reference to Neil Armstrong's quote "That's one small step for man, one giant leap for mankind". At the "Destination Moon" lunar rover ride, there is a reference to Ralph and Alice Kramden from the sitcom The Honeymooners. When Fry and Leela are on the surface of the moon and it starts to get dark, it is possible to hear in the background the first chord of the song "Breathe" from Pink Floyd's album The Dark Side of the Moon.

text: During the sequence where Amy attempts to retrieve the keys for the Planet Express Ship from the vending machine, an

text: arcade game

text: titled Gender-Neutral Pac-Person can be seen in the background, a reference to the

text: Namco

text: arcade games

text: Pac-Man

text: and

text: Ms. Pac-Man

text: .Also, The Goophy Gopher Revue is said to have been sponsored by

text: Monsanto

text: , a bioengineering conglomerate from the United States. Crater Face, the Lunar Park mascot, is a reference to the moon from the 1902 French silent film

text: A Trip to the Moon

text: . Bender impales Crater Face in the eye with his beer bottle after Crater Face attempts to confiscate his alcohol, which is another reference to the film as the astronomers' capsule (which resembles a bottle) hitting the moon's eye when it crashes. The title of the episode itself is a reference to the quote "The Eagle has landed" said by astronaut

text: Neil Armstrong

text: when he and

text: Buzz Aldrin

text: touched down on the Moon during the Apollo 11 mission. Fry nearly makes a reference to Neil Armstrong's quote "That's one small step for man, one giant leap for mankind". At the "Destination Moon" lunar rover ride, there is a reference to Ralph and Alice Kramden from the sitcom

text: The Honeymooners

text: . When Fry and Leela are on the surface of the moon and it starts to get dark, it is possible to hear in the background the first chord of the song "

text: Breathe

text: " from

text: Pink Floyd

text: 's album

text: The Dark Side of the Moon

text: He suspected a correlation between the moon and seismic activity on earth, and developed his theory with the use of statistics.  He found that earth tremors occurred most frequently during full and new moons, when the earth is between the sun and moon, when the moon is between the earth and sun, and when the moon is closest in its orbit to the earth.  He also found indications in some cases that the moon had crossed the meridian of affected locales at the time of the earthquake.

text: Not all deformations originate within the Earth. The gravity of the Moon and Sun cause the Earth's surface at a given point to undulate by tenths of meters over a nearly 12-hour period (see Earth tide).

text: Not all deformations originate within the Earth. The gravity of the Moon and Sun cause the Earth's surface at a given point to undulate by tenths of meters over a nearly 12-hour period (see

text: Earth tide

text: Astronauts on the Apollo 11, 14, and 15 missions left retroreflectors on the Moon as part of the Lunar Laser Ranging Experiment. The Soviet Lunokhod 1 and Lunokhod 2 rovers also carried smaller arrays. Reflected signals were initially received from Lunokhod 1, but no return signals were detected from 1971 until 2010, at least in part due to some uncertainty in its location on the Moon.  In 2010, it was found in Lunar Reconnaissance Orbiter photographs and the retroreflectors have been used again.  Lunokhod 2's array continues to return signals to Earth. Even under good viewing conditions, only a single reflected photon is received every few seconds. This makes the job of filtering laser-generated photons from naturally occurring photons challenging.

text: Astronaut

text: s on the

text: Apollo 11

text: , and

text: missions left retroreflectors on the

text: Moon

text: as part of the

text: Lunar Laser Ranging Experiment

text: . The

text: Soviet

text: Lunokhod 1

text: and

text: Lunokhod 2

text: rovers also carried smaller arrays. Reflected signals were initially received from Lunokhod 1, but no return signals were detected from 1971 until 2010, at least in part due to some uncertainty in its location on the Moon.  In 2010, it was found in

text: Lunar Reconnaissance Orbiter

text: photographs and the retroreflectors have been used again.  Lunokhod 2's array continues to return signals to Earth. Even under good viewing conditions, only a single reflected photon is received every few seconds. This makes the job of filtering laser-generated photons from naturally occurring photons challenging.

text: Prior to the moon landings O'Keefe developed a theory that tektites, natural glass objects found in discrete strewn fields around the world, are actually volcanic ejecta from the Moon. He suggested that explosive, hydrogen-driven lunar volcanoes may be the mechanism that launched the tektites to Earth. After the moon landings his claim was apparently supported by a chemical analysis of a portion of lunar sample 12013 retrieved by Apollo 12 astronaut Pete Conrad that showed a similar major element composition to some tektites found in Southeast Asia. Some Apollo 14 samples also had chemistries similar to tektites. However, most other lunar data strongly challenged the O'Keefe hypothesis, and almost all researchers in this field now accept that tektites are of terrestrial origin, the products of large meteorite or cometary impacts on Earth. This is supported by geochemical, isotopic and mineralogical evidence, and the fact that most tektite strewn fields can now be confidently matched to known impact craters of similar age on Earth.

text: Prior to the moon landings O'Keefe developed a theory that

text: tektites

text: , natural glass objects found in discrete strewn fields around the world, are actually volcanic ejecta from the

text: Moon

text: . He suggested that explosive, hydrogen-driven lunar volcanoes may be the mechanism that launched the tektites to Earth. After the moon landings his claim was apparently supported by a chemical analysis of a portion of lunar sample 12013 retrieved by

text: Apollo 12

text: astronaut

text: Pete Conrad

text: that showed a similar major element composition to some tektites found in Southeast Asia. Some Apollo 14 samples also had chemistries similar to tektites. However, most other lunar data strongly challenged the O'Keefe hypothesis, and almost all researchers in this field now accept that tektites are of terrestrial origin, the products of large meteorite or cometary impacts on Earth. This is supported by geochemical, isotopic and mineralogical evidence, and the fact that most tektite strewn fields can now be confidently matched to known

text: impact craters

text: of similar age on Earth.

text: The concept of a habitable zone has been used by planetary scientists and astrobiologists to define an orbital region around a star in which a planet (or moon) can sustain liquid water. Under this definition, the inner edge of the habitable zone (i.e., the closest point to a star that a planet can be until it can no longer sustain liquid water) is determined by the point in which the runaway greenhouse process occurs. For sun-like stars, this inner edge is estimated to reside at roughly 84% the distance from the Earth to the sun although feedback such as cloud-induced albedo increase could modify this estimate somewhat.

text: The concept of a

text: habitable zone

text: has been used by planetary scientists and astrobiologists to define an orbital region around a star in which a planet (or moon) can sustain liquid water. Under this definition, the inner edge of the habitable zone (i.e., the closest point to a star that a planet can be until it can no longer sustain liquid water) is determined by the point in which the runaway greenhouse process occurs. For sun-like stars, this inner edge is estimated to reside at roughly 84% the distance from the Earth to the sun although feedback such as cloud-induced albedo increase could modify this estimate somewhat.

text: The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to "lunar science") is quite different from that of Earth. The Moon lacks a significant atmosphere, which eliminates erosion due to weather; it does not have any form of plate tectonics, it has a lower gravity, and because of its small size, it cooled more rapidly. The complex geomorphology of the lunar surface has been formed by a combination of processes, especially impact cratering and volcanism. The Moon is a differentiated body, with a crust, mantle, and core.

text: The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to "lunar science") is quite different from that of

text: Earth

text: . The

text: Moon

text: lacks a significant

text: atmosphere

text: , which eliminates

text: erosion

text: due to

text: weather

text: ; it does not have any form of

text: plate tectonics

text: , it has a lower

text: gravity

text: , and because of its small size, it cooled more rapidly. The complex

text: geomorphology

text: of the lunar surface has been formed by a combination of processes, especially

text: impact crater

text: ing and

text: volcanism

text: . The Moon is a differentiated body, with a

text: crust

text: mantle

text: , and

text: core

text: Ten Bruggencate is a lunar impact crater that lies on the far side of the Moon from the Earth, just to the east of the younger crater Lane. To the southeast of Ten Bruggencate is Chauvenet.

text: Ten Bruggencate is a

text: lunar

text: impact crater

text: that lies on the

text: far side

text: of the

text: Moon

text: from the

text: Earth

text: , just to the east of the younger crater

text: Lane

text: . To the southeast of Ten Bruggencate is

text: Chauvenet

text: Among the remaining irregular moons, Sao and Laomedeia follow prograde orbits, whereas Halimede, Psamathe and Neso follow retrograde orbits. Given the similarity of their orbits, it was suggested that Neso and Psamathe could have a common origin in the break-up of a larger moon. Psamathe and Neso have the largest orbits of any natural satellites discovered in the Solar system to date. They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. Neptune has the largest Hill sphere in the Solar System, owing primarily to its large distance from the Sun; this allows it to retain control of such distant moons. Nevertheless, Jupiter's S/2003 J 2 orbits at the greatest percentage of the primary's Hill radius of all the moons in the Solar System on average, and the Jovian moons in the Carme and Pasiphae groups orbit at a greater percentage of their primary's Hill radius than Psamathe and Neso.

text: Among the remaining irregular moons, Sao and Laomedeia follow prograde orbits, whereas Halimede, Psamathe and Neso follow retrograde orbits. Given the similarity of their orbits, it was suggested that Neso and Psamathe could have a common origin in the break-up of a larger moon. Psamathe and Neso have the largest orbits of any natural satellites discovered in the Solar system to date. They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon. Neptune has the largest

text: Hill sphere

text: in the Solar System, owing primarily to its large distance from the Sun; this allows it to retain control of such distant moons. Nevertheless, Jupiter's

text: S/2003 J 2

text: orbits at the greatest percentage of the primary's Hill radius of all the moons in the Solar System on average, and the Jovian moons in the

text: Carme

text: and

text: Pasiphae group

text: s orbit at a greater percentage of their primary's Hill radius than Psamathe and Neso.

text: Two lunar probes were launched in 2009; the Lunar Reconnaissance Orbiter and Lunar Crater Observation and Sensing Satellite were launched on a single Atlas V rocket on 18 June. LRO entered selenocentric orbit and began a series of experiments, whilst LCROSS remained attached to the Centaur upper stage of the carrier rocket, and flew past the Moon. After orbiting the Earth twice, LCROSS separated from the upper stage and both it and the Centaur impacted the Cabeus crater at the South Pole of the Moon, on 9 October. By observing the Centaur's impact, LCROSS was able to confirm the presence of water on the Moon. Several other Lunar probes ceased operations in 2009; Okina impacted the far side of the Moon on 12 February, Chang'e 1 was deorbited on 1 March, having completed its operations. Kaguya was also deorbited following a successful mission, impacting near Gill crater on 12 June. The Chandrayaan-1 spacecraft failed on 29 August, having operated for less than half of its design life.

text: Two

text: lunar

text: probes were launched in 2009; the

text: Lunar Reconnaissance Orbiter

text: and

text: Lunar Crater Observation and Sensing Satellite

text: were launched on a single

text: Atlas V

text: rocket on 18 June. LRO entered

text: selenocentric orbit

text: and began a series of experiments, whilst LCROSS remained attached to the

text: Centaur

text: upper stage of the carrier rocket, and flew past the Moon. After orbiting the Earth twice, LCROSS separated from the upper stage and both it and the Centaur impacted the

text: Cabeus

text: crater at the South Pole of the Moon, on 9 October. By observing the Centaur's impact, LCROSS was able to confirm the presence of water on the Moon. Several other Lunar probes ceased operations in 2009;

text: Okina

text: impacted the far side of the Moon on 12 February,

text: Chang'e 1

text: was deorbited on 1 March, having completed its operations.

text: Kaguya

text: was also deorbited following a successful mission, impacting near

text: Gill

text: crater on 12 June. The

text: spacecraft failed on 29 August, having operated for less than half of its design life.

text: In a review article, Schlesinger et al. list the properties of particulate matter that might elicit adverse effects. The properties that seem pertinent to lunar dust include: size distribution, mass concentration, particle surface area, number concentration, acidity, particle surface chemistry, particle reactivity, metal content, water solubility, and geometric form. In attempting to consider each of these properties, one property emerges as the most difficult to study; particle surface chemistry may be difficult to understand because the environment on the lunar surface is unlike any on Earth, and is likely to alter the surface of dust grains in a way that will render them highly reactive. Recreating the processes that could affect grain surface reactivity on the moon is difficult in an Earth-bound laboratory. Freshly fractured quartz is distinctly more toxic to the rat respiratory system than aged quartz. Quartz and lunar dust may have similar toxic properties, but breaking of surface bonds on mineral substrates has been shown to increase the toxicity of the well-studied mineral quartz.

text: By comparison, the Earth's Moon moves in an ellipse with one of its foci at the barycenter of the Moon and the Earth, this barycenter being within the Earth itself, while the Earth (more precisely, its center) moves in an ellipse with one focus at that same barycenter within the Earth. The barycenter is about three-quarters of the distance from Earth's center to its surface.

text: By comparison, the Earth's

text: Moon

text: moves in an ellipse with one of its foci at the barycenter of the Moon and the

text: Earth

text: , this barycenter being within the Earth itself, while the Earth (more precisely, its center) moves in an ellipse with one focus at that same barycenter within the Earth. The barycenter is about three-quarters of the distance from Earth's center to its surface.

text: The origin and development of water on terrestrial planets, Venus, Earth, Mars, and the closely related Earth's Moon, varies with each planetary body, with the exact origins remaining unclear. Additionally, the terrestrial dwarf planet, Ceres is known to have water ice on its surface.

text: The origin and development of

text: water

text: on

text: terrestrial planet

text: s,

text: Venus

text: Earth

text: Mars

text: , and the closely related Earth's

text: Moon

text: , varies with each planetary body, with the exact origins remaining unclear. Additionally, the terrestrial dwarf planet,

text: Ceres

text: is known to have water ice on its surface.

text: Another thing to consider is that the motion of the Moon is not a perfect circle.  Its orbit is distinctly elliptic, so the lunar distance from Earth varies throughout the lunar cycle. This varying distance changes the apparent diameter of the Moon, and therefore influences the chances, duration, and type (partial, annular, total, mixed) of an eclipse.  This orbital period is called the anomalistic month, and together with the synodic month causes the so-called "full moon cycle" of about 14 lunations in the timings and appearances of full (and new) Moons. The Moon moves faster when it is closer to the Earth (near perigee) and slower when it is near apogee (furthest distance), thus periodically changing the timing of syzygies by up to ±14 hours (relative to their mean timing), and changing the apparent lunar angular diameter by about ±6%.  An eclipse cycle must comprise close to an integer number of anomalistic months in order to perform well in predicting eclipses.

text: Another thing to consider is that the motion of the Moon is not a perfect circle.  Its orbit is distinctly elliptic, so the lunar distance from Earth varies throughout the lunar cycle. This varying distance changes the apparent diameter of the Moon, and therefore influences the chances, duration, and type (partial, annular, total, mixed) of an eclipse.  This orbital period is called the

text: anomalistic month

text: , and together with the synodic month causes the so-called "

text: full moon cycle

text: " of about 14 lunations in the timings and appearances of full (and new) Moons. The Moon moves faster when it is closer to the Earth (near perigee) and slower when it is near apogee (furthest distance), thus periodically changing the timing of syzygies by up to ±14 hours (relative to their mean timing), and changing the apparent lunar angular diameter by about ±6%.  An eclipse cycle must comprise close to an integer number of anomalistic months in order to perform well in predicting eclipses.

text: Around the Moon (, 1870), Jules Verne's sequel to From the Earth to the Moon, is a science fiction novel which continues the trip to the moon which was only partially described in the  previous novel. It was later combined with From the Earth to the Moon to create A Trip to the Moon and Around It.

text: Around the Moon (, 1870),

text: Jules Verne

text: 's sequel to

text: From the Earth to the Moon

text: , is a

text: science fiction

text: novel which continues the trip to the moon which was only partially described in the  previous novel. It was later combined with From the Earth to the Moon to create A Trip to the Moon and Around It.

text: Themisto's orbit is unusual: unlike most of Jupiter's moons, which orbit in distinct groups, Themisto orbits alone.  The moon is located midway between the Galilean moons and the first group of prograde irregular moons, called the Himalia group.

text: Themisto's orbit is unusual: unlike most of

text: Jupiter's moons

text: , which orbit in distinct groups, Themisto orbits alone.  The moon is located midway between the

text: Galilean moons

text: and the first group of prograde irregular moons, called the

text: Himalia group

text: Laveran is a lunar impact crater located on the lunar far side near the southern pole. The crater is located in between the prominent craters Schrödinger, Zeeman, Ashbrook, and South of De Forest. Laveran was adopted and named after French physician Charles Louis Alphonse Laveran by the IAU in 2009.

text: Laveran is a

text: lunar

text: impact crater

text: located on the

text: lunar far side

text: near the southern pole. The crater is located in between the prominent craters

text: Schrödinger

text: Zeeman

text: Ashbrook

text: , and South of

text: De Forest

text: . Laveran was adopted and named after French

text: physician

text: Charles Louis Alphonse Laveran

text: by the

text: IAU

text: in 2009.

text: The South Pole–Aitken basin is a huge impact crater on the far side of the Moon. Roughly  in diameter and  deep, it is one of the largest known impact craters in the Solar System. It is the largest, oldest and deepest basin recognized on the Moon. It was named for two features on opposing sides; the crater Aitken on the northern end and the southern lunar pole at the other end. The outer rim of this basin can be seen from Earth as a huge chain of mountains located on the lunar southern limb, sometimes called "Leibnitz mountains", although this name has not been considered official by the International Astronomical Union.

text: The South Pole–Aitken basin is a huge

text: impact crater

text: on the

text: far side of the Moon

text: . Roughly  in diameter and  deep, it is one of the

text: largest known impact craters in the Solar System

text: . It is the largest, oldest and deepest basin recognized on the Moon. It was named for two features on opposing sides; the crater

text: Aitken

text: on the northern end and the southern lunar pole at the other end. The outer rim of this basin can be seen from Earth as a huge chain of mountains located on the lunar southern limb, sometimes called "Leibnitz mountains", although this name has not been considered official by the

text: International Astronomical Union

text: Project Diana, named for the Roman moon goddess Diana, was an experimental project of the US Army Signal Corps in 1946 to bounce radar signals off the Moon and receive the reflected signals.  This was the first experiment in radar astronomy and the first active attempt to probe another celestial body.  It was the inspiration for later EME (Earth-Moon-Earth) communication techniques.

text: Project Diana, named for the

text: Roman

text: moon goddess

text: Diana

text: , was an experimental project of the

text: US Army Signal Corps

text: in 1946 to bounce

text: radar

text: signals off the

text: Moon

text: and receive the reflected signals.  This was the first experiment in

text: radar astronomy

text: and the first active attempt to probe another

text: celestial body

text: .  It was the inspiration for later

text: EME

text: (Earth-Moon-Earth) communication techniques.

text: Known or suspected collisional families include numerous asteroid families, most of the irregular moons of the outer planets, the Earth and the Moon, and the dwarf planets Pluto, Eris, and Haumea and their moons.

text: Known or suspected collisional families include numerous

text: asteroid families

text: , most of the

text: irregular moon

text: s of the outer planets, the Earth and the

text: Moon

text: , and the dwarf planets

text: Pluto

text: Eris

text: , and

text: Haumea

text: and their moons.

text: Cold surface oceans or lakes are found on two worlds, Earth and Saturn's moon Titan. Lava lakes are found on Earth and Jupiter's moon Io. Subsurface oceans or seas occur on the other Galilean moons of Jupiter, Saturn's moons Titan and Enceladus, and are suspected on the some of Saturn's other moons, the asteroid Ceres, the larger trans-Neptunian objects, and ice planets in planetary systems. Recent analysis of the interior of Ganymede, taking into account the effects of salt, suggests that it and some of the other icy bodies may not have a single interior global ocean but several stacked ones, separated by different phases of ice, with the lowest liquid layer adjacent to the rocky mantle below.

text: Cold surface oceans or lakes are found on two worlds, Earth and Saturn's moon Titan.

text: Lava lake

text: s are found on Earth and Jupiter's moon Io.

text: Subsurface ocean

text: s or seas occur on the other Galilean moons of Jupiter, Saturn's moons

text: Titan

text: and

text: Enceladus

text: , and are suspected on the some of Saturn's other moons, the asteroid Ceres, the larger

text: trans-Neptunian object

text: s, and

text: ice planet

text: s in

text: planetary system

text: s. Recent analysis of the interior of

text: Ganymede

text: , taking into account the effects of salt, suggests that it and some of the other icy bodies may not have a single interior global ocean but several stacked ones, separated by different

text: phases of ice

text: , with the lowest liquid layer adjacent to the rocky mantle below.

text: Doppler is a lunar impact crater named for Christian Doppler that is located at the southern edge of the walled plain Korolev, on the far side of the Moon. To the east are the craters Das and Galois. Farther to the southwest of Doppler is Mohorovičić.

text: Doppler is a

text: lunar

text: impact crater

text: named for

text: Christian Doppler

text: that is located at the southern edge of the walled plain

text: Korolev

text: , on the

text: far side

text: of the

text: Moon

text: . To the east are the craters

text: Das

text: and

text: Galois

text: . Farther to the southwest of Doppler is

text: Mohorovičić

text: In most locations, the largest constituent is the "principal lunar semi-diurnal", also known as the M2 (or M) tidal constituent. Its period is about 12 hours and 25.2 minutes, exactly half a tidal lunar day, which is the average time separating one lunar zenith from the next, and thus is the time required for the Earth to rotate once relative to the Moon. Simple tide clocks track this constituent. The lunar day is longer than the Earth day because the Moon orbits in the same direction the Earth spins. This is analogous to the minute hand on a watch crossing the hour hand at 12:00 and then again at about 1:05½ (not at 1:00).

text: In most locations, the largest constituent is the "principal lunar semi-diurnal", also known as the M2 (or M) tidal constituent. Its period is about 12 hours and 25.2 minutes, exactly half a tidal lunar day, which is the average time separating one lunar

text: zenith

text: from the next, and thus is the time required for the Earth to rotate once relative to the Moon. Simple

text: tide clock

text: s track this constituent. The lunar day is longer than the Earth day because the Moon orbits in the same direction the Earth spins. This is analogous to the minute hand on a watch crossing the hour hand at 12:00 and then again at about 1:05½ (not at 1:00).

text: In her 40 year long career, Maria Luisa Crawford wrote 68 separate articles in various journals. Her area of research changed several times throughout her career. However, the majority of Crawford's work centered around gaining an understanding of past geological processes related to the earth's crust. There was a period of time when Crawford became very interested in lunar petrology. She was involved in the study of several moon rocks that had been retrieved during the Apollo missions. By studying these rocks she was able to determine that sometime in the moon's history large meteorites struck its surface causing flood lavas. The work she did with lunar rocks is still mentioned in lunar studies to this day.

text: The tidal acceleration of the Moon slows the rotation rate of the Earth and increases the Earth-Moon distance. Friction effects—between the core and mantle and between the atmosphere and surface—can dissipate the Earth's rotational energy. These combined effects are expected to increase the length of the day by more than 1.5 hours over the next 250 million years, and to increase the obliquity by about a half degree. The distance to the Moon will increase by about 1.5 Earth radii during the same period.

text: The

text: tidal acceleration

text: of the Moon slows the rotation rate of the Earth and increases the

text: Earth-Moon distance

text: . Friction effects—between the core and

text: mantle

text: and between the atmosphere and surface—can dissipate the Earth's rotational energy. These combined effects are expected to increase the

text: length of the day

text: by more than 1.5 hours over the next 250 million years, and to increase the

text: obliquity

text: by about a half degree. The distance to the Moon will increase by about 1.5 Earth radii during the same period.

text: To return to Earth, the escape velocity of the Moon must be overcome for the spacecraft to escape the gravity well of the Moon. Rockets must be used to leave the Moon and return to space. Upon reaching Earth, atmospheric entry techniques are used to absorb the kinetic energy of a returning spacecraft and reduce its speed for safe landing. These functions greatly complicate a moon landing mission and lead to many additional operational considerations. Any moon departure rocket must first be carried to the Moon's surface by a moon landing rocket, increasing the latter's required size. The Moon departure rocket, larger moon landing rocket and any Earth atmosphere entry equipment such as heat shields and parachutes must in turn be lifted by the original launch vehicle, greatly increasing its size by a significant and almost prohibitive degree.

text: To return to Earth, the escape velocity of the Moon must be overcome for the spacecraft to escape the

text: gravity well

text: of the Moon. Rockets must be used to leave the Moon and return to space. Upon reaching Earth, atmospheric entry techniques are used to absorb the

text: kinetic energy

text: of a returning spacecraft and reduce its speed for safe landing. These functions greatly complicate a moon landing mission and lead to many additional operational considerations. Any moon departure rocket must first be carried to the Moon's surface by a moon landing rocket, increasing the latter's required size. The Moon departure rocket, larger moon landing rocket and any Earth atmosphere entry equipment such as heat shields and

text: parachute

text: s must in turn be lifted by the original launch vehicle, greatly increasing its size by a significant and almost prohibitive degree.

text: Gliese 876 b, discovered in 1998, and Gliese 876 c, discovered in 2001, are both gas giants discovered in the habitable zone around Gliese 876. Although they are not thought to possess significant water at their surfaces, both may have habitable moons. Upsilon Andromedae d, discovered in 1999, is a gas giant in its star's circumstellar habitable zone considered to be large enough to favor the formation of large, Earth-like moons.

text: Gliese 876 b

text: , discovered in 1998, and

text: Gliese 876 c

text: , discovered in 2001, are both gas giants discovered in the habitable zone around

text: Gliese 876

text: . Although they are not thought to possess significant water at their surfaces, both may have

text: habitable moons

text: Upsilon Andromedae d

text: , discovered in 1999, is a gas giant in its star's circumstellar habitable zone considered to be large enough to favor the formation of large, Earth-like moons.

text: When Shea was hired by NASA, President John F. Kennedy's commitment to landing men on the Moon was still only seven months old, and many of the major decisions that shaped the Apollo program were yet to be made. Foremost among these was the mode that NASA would use to land on the Moon. When Shea first began to consider the issue in 1962, most NASA engineers and managersincluding Wernher von Braun, the director of the Marshall Space Flight Centerfavored either an approach called direct ascent, where the Apollo spacecraft would land on the Moon and return to the Earth as one unit, or Earth orbit rendezvous, where the spacecraft would be assembled while still in orbit around the Earth. However, dissenters such as John Houbolt, a Langley engineer, favored an approach that was then considered to be more risky: lunar orbit rendezvous, in which two spacecraft would be used. A command/service module (CSM) would remain in orbit around the Moon, while a lunar module would land on the Moon and return to dock with the CSM in lunar orbit, then be discarded.

text: When Shea was hired by NASA, President

text: John F. Kennedy

text: 's commitment to

text: landing men on the Moon

text: was still only seven months old, and many of the major decisions that shaped the

text: Apollo program

text: were yet to be made. Foremost among these was the mode that NASA would use to land on the Moon. When Shea first began to consider the issue in 1962, most NASA engineers and managersincluding

text: Wernher von Braun

text: , the director of the

text: Marshall Space Flight Center

text: favored either an approach called

text: direct ascent

text: , where the Apollo spacecraft would land on the Moon and return to the Earth as one unit, or

text: Earth orbit rendezvous

text: , where the spacecraft would be assembled while still in orbit around the Earth. However, dissenters such as

text: John Houbolt

text: , a

text: Langley

text: engineer, favored an approach that was then considered to be more risky:

text: lunar orbit rendezvous

text: , in which two spacecraft would be used. A

text: command/service module

text: (CSM) would remain in

text: orbit

text: around the Moon, while a

text: lunar module

text: would land on the Moon and return to dock with the CSM in lunar orbit, then be discarded.

text:
|- bgcolor="bbffbb"| 1| October 31| Philadelphia| | Andrea Bargnani (20)| Carlos Delfino, Anthony Parker (6) | T. J. Ford (12)| Air Canada Centre
19,800| 1–0|- bgcolor="#bbffbb" | 2| November 2| @ New Jersey| | Andrea Bargnani (21)| Andrea Bargnani, Carlos Delfino (6)| José Calderón (8)| Izod Center
14,980| 2–0|- bgcolor="#ffcccc"| 3| November 4| Boston| | T. J. Ford (32)| Chris Bosh (10)| T. J. Ford (5)| Air Canada Centre
19,800| 2–1|- bgcolor="#ffcccc"| 4| November 6| @ Milwaukee| | Juan Dixon (20)| Kris Humphries (9)| José Calderón (8)| Bradley Center
13,495| 2–2|- bgcolor="#ffcccc"| 5| November 7| Orlando| | Chris Bosh (26)| Chris Bosh (10)| T. J. Ford (8)| Air Canada Centre
17,977| 2–3|- bgcolor="#bbffbb"| 6| November 9| @ Philadelphia| | Chris Bosh (24)| Chris Bosh (10)| José Calderón (7)| Wachovia Center
10,886| 3–3|- bgcolor="#bbffbb"| 7| November 10| @ Chicago| | Carlos Delfino (16)| Radoslav Nesterović (8)| T. J. Ford (14)| United Center
22,467| 4–3|- bgcolor="#ffcccc"| 8| November 14| Utah| | Anthony Parker (19)| Kris Humphries (14)| T. J. Ford (8)| Air Canada Centre
17,337| 4–4|- bgcolor="#bbffbb"| 9| November 16| Indiana| | Chris Bosh (22)| Jamario Moon (7)| José Calderón (10)| Air Canada Centre
19,800| 5–4|- bgcolor="#ffcccc"| 10| November 18| Golden State| | T. J. Ford (29)| Chris Bosh (11)| T. J. Ford (9)| Air Canada Centre
19,800| 5–5|- bgcolor="#ffcccc"| 11| November 20| @ Dallas| | Chris Bosh (31)| Chris Bosh, Jamario Moon (12)| José Calderón (6)| American Airlines Center
20,272| 5–6|- bgcolor="#bbffbb"| 12| November 21| @ Memphis| | Chris Bosh (22)| Chris Bosh (19)| José Calderón (8)| FedExForum
12,217| 6–6|- bgcolor="#ffcccc"| 13| November 24| @ Cleveland| | Chris Bosh (41)| Anthony Parker (7)| José Calderón (13)| Quicken Loans Arena
20,018| 6–7|- bgcolor="#bbffbb"| 14| November 25| Chicago| | José Calderón (19)| Chris Bosh (13)| José Calderón (14)| Air Canada Centre
19,800| 7–7|- bgcolor="#bbffbb"| 15| November 28| Memphis| | Anthony Parker (19)| Jamario Moon, Anthony Parker (8)| José Calderón (10)| Air Canada Centre
18,906| 8–7|- bgcolor="#bbffbb"| 16| November 30| Cleveland| | Andrea Bargnani (26)| Jamario Moon, Radoslav Nesterović (9)| José Calderón (10)| Air Canada Centre
19,800| 9–7|- bgcolor="#ffcccc"| 17| December 1| @ Washington| | Jason Kapono (23)| Jamario Moon (13)| José Calderón (11)| Verizon Center
20,173| 9–8|- bgcolor="#bbffbb"| 18| December 3| Charlotte| | Carlos Delfino, Kris Humphries (17)| Jamario Moon (12)| José Calderón (9)| Air Canada Centre
17,439| 10–8|- bgcolor="#ffcccc"| 19| December 5| Phoenix| | T. J. Ford (27)| Jamario Moon (10)| José Calderón (9)| Air Canada Centre
19,800| 10–9|- bgcolor="#ffcccc"| 20| December 7| @ Boston| | Anthony Parker (13)| Joey Graham (6)| Carlos Delfino, Darrick Martin (4)| TD Banknorth Garden
18,624| 10–10|- bgcolor="#bbffbb"| 21| December 9 | Houston| | Chris Bosh (21)| Chris Bosh (10)| José Calderón (6)| Air Canada Centre
19,800| 11–10|- bgcolor="#bbffbb"| 22| December 11| @ Atlanta| | T. J. Ford (26)| Chris Bosh (13)| T. J. Ford (8)| Philips Arena
13,173| 12–10|- bgcolor="#bbffbb"| 23| December 12| Dallas| | Chris Bosh (17)| Kris Humphries (12)| José Calderón (7)| Air Canada Centre
19,800| 13–10|- bgcolor="#bbffbb"| 24| December 14| @ Indiana| | Jason Kapono (29)| Chris Bosh (16)| José Calderón (16)| Conseco Fieldhouse
10,437| 14–10|- bgcolor="#ffcccc"| 25| December 16| Boston| | Chris Bosh (17)| Chris Bosh (13)| Chris Bosh, José Calderón (5)| Air Canada Centre
19,800| 14–11|- bgcolor="#bbffbb"| 26| December 18| @ L.A. Clippers| | Chris Bosh (24)| Chris Bosh (9)| José Calderón (9)| Staples Center
14,455| 15–11|- bgcolor="#ffcccc"| 27| December 19| @ Portland| | José Calderón (19)| Chris Bosh (11)| José Calderón (9)| Rose Garden Arena
16,066| 15–12|- bgcolor="#ffcccc"| 28| December 21| @ Seattle| | Chris Bosh (26)| Chris Bosh (13)| José Calderón (16)| KeyArena
13,661| 15–13|- bgcolor="#ffcccc"| 29| December 22| @ Phoenix| | Chris Bosh (42)| Chris Bosh (13)| José Calderón, Juan Dixon (4)| US Airways Center
18,422| 15–14|- bgcolor="#bbffbb"| 30| December 28| @ San Antonio| | Jason Kapono (15)| Kris Humphries (11)| José Calderón (5)| AT&T Center
18,797| 16–14|- bgcolor="#ffcccc"| 31| December 29| @ Houston| | Chris Bosh (19)| Chris Bosh (12)| José Calderón (10)| Toyota Center
18,103| 16–15|- bgcolor="#bbffbb"| 32| December 31| @ New Orleans| | Chris Bosh (29)| Jamario Moon (10)| José Calderón (12)| New Orleans Arena
11,444| 17–15|- bgcolor="#ffcccc"| 33| January 4| Detroit| | Andrea Bargnani (25)| Chris Bosh (16)| José Calderón (9)| Air Canada Centre
19,800| 17–16|- bgcolor="#ffcccc"| 34| January 6| Cleveland| | Chris Bosh (23)| Anthony Parker (9)| José Calderón (11)| Air Canada Centre
19,800| 17–17|- bgcolor="#bbffbb"| 35| January 9| Philadelphia| | Anthony Parker (22)| Jamario Moon (9)| José Calderón (9)| Air Canada Centre
18,067| 18–17|- bgcolor="#bbffbb"| 36| January 11| @ New York| | Chris Bosh (40)| Chris Bosh (11)| José Calderón (8)| Madison Square Garden
17,456| 19–17|- bgcolor="#bbffbb"| 37| January 13| Portland| | Chris Bosh (38)| Chris Bosh (14)| José Calderón (10)| Air Canada Centre
19,800| 20–17|- bgcolor="#ffcccc"| 38| January 15| @ Detroit| | Chris Bosh (16)| Chris Bosh (11)| José Calderón (5)| The Palace of Auburn Hills
22,076| 20–18|- bgcolor="#bbffbb"| 39| January 16| Sacramento| | Chris Bosh (31)| Chris Bosh (9)| José Calderón (14)| Air Canada Centre
17,760| 21–18|- bgcolor="#bbffbb"| 40| January 18| Atlanta| | Chris Bosh (35)| Chris Bosh (9)| José Calderón (9)| Air Canada Centre
19,800| 22–18|- bgcolor="#ffcccc"| 41| January 19| @ Philadelphia| | Chris Bosh (25)| Chris Bosh, Jamario Moon (9)| José Calderón (11)| Wachovia Center
13,853| 22–19|- bgcolor="#bbffbb"| 42|  January 23| @ Boston| | José Calderón (24)| Andrea Bargnani, Chris Bosh (7)| José Calderón (13)| TD Banknorth Garden
18,624| 23–19|- bgcolor="#bbffbb"| 43| January 25| Milwaukee| | Chris Bosh (32)| Andrea Bargnani, Chris Bosh (7)| José Calderón (12)| Air Canada Centre
19,800| 24–19|- bgcolor="#ffcccc"| 44| January 29| @ Washington| | Chris Bosh (37)| Chris Bosh (12)| José Calderón (13)| Verizon Center
12,905| 24–20|- bgcolor="#bbffbb"| 45| January 30| Washington| | Andrea Bargnani (19)| Radoslav Nesterović (8)| José Calderón (11)| Air Canada Centre
19,800| 25–20|- bgcolor="#ffcccc"| 46| February 1| L.A. Lakers| | Andrea Bargnani (28)| Chris Bosh (15)| Juan Dixon (6)| Air Canada Centre
19,800| 25–21 |- bgcolor="#bbffbb"| 47| February 4| @ Miami| | Chris Bosh (24)| Jamario Moon (9)| José Calderón (10)| American Airlines Arena
19,600| 26–21|- bgcolor="#ffcccc"| 48| February 8 | L.A. Clippers| | Chris Bosh (29)| Chris Bosh (12)| José Calderón (14)| Air Canada Centre
19,800| 26–22|- bgcolor="#bbffbb"| 49| February 10| @ Minnesota| | Andrea Bargnani (16)| Chris Bosh, Carlos Delfino (9)| T. J. Ford (13)| Target Center
13,785| 27–22|- bgcolor="#ffcccc"| 50| February 11| San Antonio| | José Calderón (27)| Chris Bosh, Carlos Delfino, Jamario Moon (8)| José Calderón (6)| Air Canada Centre
19,800| 27–23|- bgcolor="#bbffbb"| 51| February 13| New Jersey| | Chris Bosh (27)| Chris Bosh, Carlos Delfino (9)| José Calderón (12)| Air Canada Centre
19,800| 28–23|- bgcolor="#bbffbb"| 52| February 20| Orlando| | Chris Bosh (40)| Jamario Moon (12)| José Calderón (13)| Air Canada Centre
19,800| 29–23|- bgcolor="#ffcccc"| 53| February 22| @ New York| | Chris Bosh (23)| Chris Bosh, Jamario Moon (8)| José Calderón (6)| Madison Square Garden
19,763| 29–24|- bgcolor="#bbffbb"| 54| February 24| New York| | Andrea Bargnani (25)| Jamario Moon, Radoslav Nesterović (8)| José Calderón (7)| Air Canada Centre
19,800| 30–24|- bgcolor="#bbffbb"| 55| February 25| @ Indiana| | Chris Bosh (24)| Anthony Parker (11)| T. J. Ford (7)| Conseco Fieldhouse
10,468| 31–24|- bgcolor="#bbffbb"| 56| February 27| Minnesota| | Chris Bosh (28)| Chris Bosh, Jamario Moon (7)| José Calderón (7)| Air Canada Centre
18,325| 32–24|- bgcolor="#ffcccc"| 57| February 29| Indiana| | Andrea Bargnani (27)| Andrea Bargnani (9)| José Calderón (11)| Air Canada Centre
19,800| 32–25|- bgcolor="#ffcccc"| 58| March 2| @ Charlotte| | Anthony Parker (24)| Kris Humphries, Anthony Parker (6)| José Calderón (10)| Charlotte Bobcats Arena
12,083| 32–26|- bgcolor="#ffcccc"| 59| March 4| @ Orlando| | T. J. Ford (20)| Carlos Delfino, Anthony Parker (9)| José Calderón, Carlos Delfino (3)| Amway Arena
17,519| 32–27|- bgcolor="#bbffbb"| 60| March 5| @ Miami| | Radoslav Nesterović (16)| Radoslav Nesterović (10)| José Calderón (13)| American Airlines Arena
19,143| 33–27|- bgcolor="#ffcccc"| 61| March 7| Washington| | Andrea Bargnani (27)| Radoslav Nesterović (12)| José Calderón (9)| Air Canada Centre
19,800| 33–28|- bgcolor="#bbffbb"| 62| March 9| Seattle| | Anthony Parker (23)| Andrea Bargnani (7)| Radoslav Nesterović (6)| Air Canada Centre
19,800| 34–28|- bgcolor="#ffcccc"| 63| March 11| @ L.A. Lakers| | T. J. Ford (28)| Radoslav Nesterović (8)| Andrea Bargnani, José Calderón (6)| Staples Center
18,997| 34–29|- bgcolor="#ffcccc"| 64| March 12| @ Golden State| | T. J. Ford (23)| Anthony Parker (9)| T. J. Ford (8)| Oracle Arena
19,596| 34–30|- bgcolor="#ffcccc"| 65| March 14| @ Denver| | Anthony Parker (19)| Carlos Delfino, Jamario Moon (7)| José Calderón (7)| Pepsi Center
17,952| 34–31|- bgcolor="#ffcccc"| 66| March 16| @ Sacramento| | Jason Kapono (26)| Radoslav Nesterović (8)| José Calderón (9)| ARCO Arena
13,963| 34–32|- bgcolor="#ffcccc"| 67| March 17| @ Utah| | José Calderón (16)| Radoslav Nesterović (12)| José Calderón (7)| EnergySolutions Arena
19,911| 34–33|- bgcolor="#bbffbb"| 68| March 19| Miami| | Andrea Bargnani, Anthony Parker (14)| Jamario Moon (14)| José Calderón (10)| Air Canada Centre
19,800| 35–33|- bgcolor="#ffcccc"| 69| March 21| @ Cleveland| | Chris Bosh (24)| Jamario Moon (10)| T. J. Ford (5)| Quicken Loans Arena
20,562| 35–34|- bgcolor="#ffcccc"| 70| March 23 || Denver| | Chris Bosh, José Calderón (17)| Jamario Moon (15)| Chris Bosh (9)| Air Canada Centre
19,800| 35–35|- bgcolor="#bbffbb" | 71| March 26| Detroit| | Chris Bosh (21)| Radoslav Nesterović (9)| T. J. Ford (9)| Air Canada Centre
19,800| 36–35|- bgcolor="#bbffbb"| 72| March 28| New York| | Chris Bosh (29)| Chris Bosh, Carlos Delfino (10)| T. J. Ford (9)| Air Canada Centre
19,800| 37–35|- bgcolor="#ffcccc"| 73| March 30| New Orleans| | Chris Bosh (21)| Chris Bosh, Kris Humphries (7)| José Calderón (11)| Air Canada Centre
19,800| 37–36|- bgcolor="#bbffbb" | 74| March 31| @ Charlotte| | Chris Bosh (32)| Radoslav Nesterović (11)| T. J. Ford (7)| Charlotte Bobcats Arena
12,188| 38–36|- bgcolor="#ffcccc"| 75| April 2| @ Atlanta| | Chris Bosh (24)| Carlos Delfino (11)| T. J. Ford (13)| Philips Arena
14,691| 38–37|- bgcolor="#ffcccc"| 76| April 4| Charlotte| | Chris Bosh, Radoslav Nesterović (23)| Radoslav Nesterović (10)| T. J. Ford (14)| Air Canada Centre
19,800| 38–38|- bgcolor="#ffcccc"| 77| April 5| @ New Jersey| | Radoslav Nesterović (22)| Radoslav Nesterović (14)| Chris Bosh (6)| Izod Center
15,927| 38–39|- bgcolor="#bbffbb"| 78| April 9| Milwaukee| | Chris Bosh (32)| Chris Bosh (11)| José Calderón (12)| Air Canada Centre
18,569| 39–39|- bgcolor="#bbffbb"| 79| April 11| New Jersey| | Carlos Delfino (24)| Chris Bosh (9)| José Calderón (10)| Air Canada Centre
19,800| 40–39|- bgcolor="#ffcccc"| 80| April 13| @ Detroit| | Chris Bosh (30)| Chris Bosh (10)| T. J. Ford (8)| The Palace of Auburn Hills
22,076| 40–40|- bgcolor="#bbffbb"| 81| April 14| Miami| | Radoslav Nesterović (20)| Andrea Bargnani, Radoslav Nesterović, Anthony Parker (7)| José Calderón (11)| Air Canada Centre
18,855| 41–40|- bgcolor="#ffcccc" | 82| April 16| @ Chicago| | T. J. Ford (18)| Kris Humphries (7)| José Calderón (8)| United Center
21,909| 41–41

text: |- bgcolor="bbffbb"| 1| October 31|

text: Philadelphia

text: Andrea Bargnani

text: Carlos Delfino

text: Anthony Parker

text: (6) |

text: T. J. Ford

text: Air Canada Centre

text: <br>19,800| 1–0|- bgcolor="#bbffbb" | 2| November 2| @

text: New Jersey

text: Andrea Bargnani

text: Andrea Bargnani

text: Carlos Delfino

text: José Calderón

text: Izod Center

text: <br>14,980| 2–0|- bgcolor="#ffcccc"| 3| November 4|

text: Boston

text: T. J. Ford

text: Chris Bosh

text: T. J. Ford

text: Air Canada Centre

text: <br>19,800| 2–1|- bgcolor="#ffcccc"| 4| November 6| @

text: Milwaukee

text: Juan Dixon

text: Kris Humphries

text: José Calderón

text: Bradley Center

text: <br>13,495| 2–2|- bgcolor="#ffcccc"| 5| November 7|

text: Orlando

text: Chris Bosh

text: Chris Bosh

text: T. J. Ford

text: Air Canada Centre

text: <br>17,977| 2–3|- bgcolor="#bbffbb"| 6| November 9| @

text: Philadelphia

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Wachovia Center

text: <br>10,886| 3–3|- bgcolor="#bbffbb"| 7| November 10| @

text: Chicago

text: Carlos Delfino

text: Radoslav Nesterović

text: T. J. Ford

text: United Center

text: <br>22,467| 4–3|- bgcolor="#ffcccc"| 8| November 14|

text: Utah

text: Anthony Parker

text: Kris Humphries

text: T. J. Ford

text: Air Canada Centre

text: <br>17,337| 4–4|- bgcolor="#bbffbb"| 9| November 16|

text: Indiana

text: Chris Bosh

text: Jamario Moon

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 5–4|- bgcolor="#ffcccc"| 10| November 18|

text: Golden State

text: T. J. Ford

text: Chris Bosh

text: T. J. Ford

text: Air Canada Centre

text: <br>19,800| 5–5|- bgcolor="#ffcccc"| 11| November 20| @

text: Dallas

text: Chris Bosh

text: Chris Bosh

text: Jamario Moon

text: José Calderón

text: American Airlines Center

text: <br>20,272| 5–6|- bgcolor="#bbffbb"| 12| November 21| @

text: Memphis

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: FedExForum

text: <br>12,217| 6–6|- bgcolor="#ffcccc"| 13| November 24| @

text: Cleveland

text: Chris Bosh

text: Anthony Parker

text: José Calderón

text: Quicken Loans Arena

text: <br>20,018| 6–7|- bgcolor="#bbffbb"| 14| November 25|

text: Chicago

text: José Calderón

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 7–7|- bgcolor="#bbffbb"| 15| November 28|

text: Memphis

text: Anthony Parker

text: Jamario Moon

text: Anthony Parker

text: José Calderón

text: Air Canada Centre

text: <br>18,906| 8–7|- bgcolor="#bbffbb"| 16| November 30|

text: Cleveland

text: Andrea Bargnani

text: Jamario Moon

text: Radoslav Nesterović

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 9–7|- bgcolor="#ffcccc"| 17| December 1| @

text: Washington

text: Jason Kapono

text: Jamario Moon

text: José Calderón

text: Verizon Center

text: <br>20,173| 9–8|- bgcolor="#bbffbb"| 18| December 3|

text: Charlotte

text: Carlos Delfino

text: Kris Humphries

text: Jamario Moon

text: José Calderón

text: Air Canada Centre

text: <br>17,439| 10–8|- bgcolor="#ffcccc"| 19| December 5|

text: Phoenix

text: T. J. Ford

text: Jamario Moon

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 10–9|- bgcolor="#ffcccc"| 20| December 7| @

text: Boston

text: Anthony Parker

text: Joey Graham

text: Carlos Delfino

text: Darrick Martin

text: TD Banknorth Garden

text: <br>18,624| 10–10|- bgcolor="#bbffbb"| 21| December 9 |

text: Houston

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 11–10|- bgcolor="#bbffbb"| 22| December 11| @

text: Atlanta

text: T. J. Ford

text: Chris Bosh

text: T. J. Ford

text: Philips Arena

text: <br>13,173| 12–10|- bgcolor="#bbffbb"| 23| December 12|

text: Dallas

text: Chris Bosh

text: Kris Humphries

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 13–10|- bgcolor="#bbffbb"| 24| December 14| @

text: Indiana

text: Jason Kapono

text: Chris Bosh

text: José Calderón

text: Conseco Fieldhouse

text: <br>10,437| 14–10|- bgcolor="#ffcccc"| 25| December 16|

text: Boston

text: Chris Bosh

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 14–11|- bgcolor="#bbffbb"| 26| December 18| @

text: L.A. Clippers

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Staples Center

text: <br>14,455| 15–11|- bgcolor="#ffcccc"| 27| December 19| @

text: Portland

text: José Calderón

text: Chris Bosh

text: José Calderón

text: Rose Garden Arena

text: <br>16,066| 15–12|- bgcolor="#ffcccc"| 28| December 21| @

text: Seattle

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: KeyArena

text: <br>13,661| 15–13|- bgcolor="#ffcccc"| 29| December 22| @

text: Phoenix

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Juan Dixon

text: US Airways Center

text: <br>18,422| 15–14|- bgcolor="#bbffbb"| 30| December 28| @

text: San Antonio

text: Jason Kapono

text: Kris Humphries

text: José Calderón

text: AT&T Center

text: <br>18,797| 16–14|- bgcolor="#ffcccc"| 31| December 29| @

text: Houston

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Toyota Center

text: <br>18,103| 16–15|- bgcolor="#bbffbb"| 32| December 31| @

text: New Orleans

text: Chris Bosh

text: Jamario Moon

text: José Calderón

text: New Orleans Arena

text: <br>11,444| 17–15|- bgcolor="#ffcccc"| 33| January 4|

text: Detroit

text: Andrea Bargnani

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 17–16|- bgcolor="#ffcccc"| 34| January 6|

text: Cleveland

text: Chris Bosh

text: Anthony Parker

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 17–17|- bgcolor="#bbffbb"| 35| January 9|

text: Philadelphia

text: Anthony Parker

text: Jamario Moon

text: José Calderón

text: Air Canada Centre

text: <br>18,067| 18–17|- bgcolor="#bbffbb"| 36| January 11| @

text: New York

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Madison Square Garden

text: <br>17,456| 19–17|- bgcolor="#bbffbb"| 37| January 13|

text: Portland

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 20–17|- bgcolor="#ffcccc"| 38| January 15| @

text: Detroit

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: The Palace of Auburn Hills

text: <br>22,076| 20–18|- bgcolor="#bbffbb"| 39| January 16|

text: Sacramento

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>17,760| 21–18|- bgcolor="#bbffbb"| 40| January 18|

text: Atlanta

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 22–18|- bgcolor="#ffcccc"| 41| January 19| @

text: Philadelphia

text: Chris Bosh

text: Chris Bosh

text: Jamario Moon

text: José Calderón

text: Wachovia Center

text: <br>13,853| 22–19|- bgcolor="#bbffbb"| 42|  January 23| @

text: Boston

text: José Calderón

text: Andrea Bargnani

text: Chris Bosh

text: José Calderón

text: TD Banknorth Garden

text: <br>18,624| 23–19|- bgcolor="#bbffbb"| 43| January 25|

text: Milwaukee

text: Chris Bosh

text: Andrea Bargnani

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 24–19|- bgcolor="#ffcccc"| 44| January 29| @

text: Washington

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Verizon Center

text: <br>12,905| 24–20|- bgcolor="#bbffbb"| 45| January 30|

text: Washington

text: Andrea Bargnani

text: Radoslav Nesterović

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 25–20|- bgcolor="#ffcccc"| 46| February 1|

text: L.A. Lakers

text: Andrea Bargnani

text: Chris Bosh

text: Juan Dixon

text: Air Canada Centre

text: <br>19,800| 25–21 |- bgcolor="#bbffbb"| 47| February 4| @

text: Miami

text: Chris Bosh

text: Jamario Moon

text: José Calderón

text: American Airlines Arena

text: <br>19,600| 26–21|- bgcolor="#ffcccc"| 48| February 8 |

text: L.A. Clippers

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 26–22|- bgcolor="#bbffbb"| 49| February 10| @

text: Minnesota

text: Andrea Bargnani

text: Chris Bosh

text: Carlos Delfino

text: T. J. Ford

text: Target Center

text: <br>13,785| 27–22|- bgcolor="#ffcccc"| 50| February 11|

text: San Antonio

text: José Calderón

text: Chris Bosh

text: Carlos Delfino

text: Jamario Moon

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 27–23|- bgcolor="#bbffbb"| 51| February 13|

text: New Jersey

text: Chris Bosh

text: Chris Bosh

text: Carlos Delfino

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 28–23|- bgcolor="#bbffbb"| 52| February 20|

text: Orlando

text: Chris Bosh

text: Jamario Moon

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 29–23|- bgcolor="#ffcccc"| 53| February 22| @

text: New York

text: Chris Bosh

text: Chris Bosh

text: Jamario Moon

text: José Calderón

text: Madison Square Garden

text: <br>19,763| 29–24|- bgcolor="#bbffbb"| 54| February 24|

text: New York

text: Andrea Bargnani

text: Jamario Moon

text: Radoslav Nesterović

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 30–24|- bgcolor="#bbffbb"| 55| February 25| @

text: Indiana

text: Chris Bosh

text: Anthony Parker

text: T. J. Ford

text: Conseco Fieldhouse

text: <br>10,468| 31–24|- bgcolor="#bbffbb"| 56| February 27|

text: Minnesota

text: Chris Bosh

text: Chris Bosh

text: Jamario Moon

text: José Calderón

text: Air Canada Centre

text: <br>18,325| 32–24|- bgcolor="#ffcccc"| 57| February 29|

text: Indiana

text: Andrea Bargnani

text: Andrea Bargnani

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 32–25|- bgcolor="#ffcccc"| 58| March 2| @

text: Charlotte

text: Anthony Parker

text: Kris Humphries

text: Anthony Parker

text: José Calderón

text: Charlotte Bobcats Arena

text: <br>12,083| 32–26|- bgcolor="#ffcccc"| 59| March 4| @

text: Orlando

text: T. J. Ford

text: Carlos Delfino

text: Anthony Parker

text: José Calderón

text: Carlos Delfino

text: Amway Arena

text: <br>17,519| 32–27|- bgcolor="#bbffbb"| 60| March 5| @

text: Miami

text: Radoslav Nesterović

text: Radoslav Nesterović

text: José Calderón

text: American Airlines Arena

text: <br>19,143| 33–27|- bgcolor="#ffcccc"| 61| March 7|

text: Washington

text: Andrea Bargnani

text: Radoslav Nesterović

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 33–28|- bgcolor="#bbffbb"| 62| March 9|

text: Seattle

text: Anthony Parker

text: Andrea Bargnani

text: Radoslav Nesterović

text: Air Canada Centre

text: <br>19,800| 34–28|- bgcolor="#ffcccc"| 63| March 11| @

text: L.A. Lakers

text: T. J. Ford

text: Radoslav Nesterović

text: Andrea Bargnani

text: José Calderón

text: Staples Center

text: <br>18,997| 34–29|- bgcolor="#ffcccc"| 64| March 12| @

text: Golden State

text: T. J. Ford

text: Anthony Parker

text: T. J. Ford

text: Oracle Arena

text: <br>19,596| 34–30|- bgcolor="#ffcccc"| 65| March 14| @

text: Denver

text: Anthony Parker

text: Carlos Delfino

text: Jamario Moon

text: José Calderón

text: Pepsi Center

text: <br>17,952| 34–31|- bgcolor="#ffcccc"| 66| March 16| @

text: Sacramento

text: Jason Kapono

text: Radoslav Nesterović

text: José Calderón

text: ARCO Arena

text: <br>13,963| 34–32|- bgcolor="#ffcccc"| 67| March 17| @

text: Utah

text: José Calderón

text: Radoslav Nesterović

text: José Calderón

text: EnergySolutions Arena

text: <br>19,911| 34–33|- bgcolor="#bbffbb"| 68| March 19|

text: Miami

text: Andrea Bargnani

text: Anthony Parker

text: Jamario Moon

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 35–33|- bgcolor="#ffcccc"| 69| March 21| @

text: Cleveland

text: Chris Bosh

text: Jamario Moon

text: T. J. Ford

text: Quicken Loans Arena

text: <br>20,562| 35–34|- bgcolor="#ffcccc"| 70| March 23 ||

text: Denver

text: Chris Bosh

text: José Calderón

text: Jamario Moon

text: Chris Bosh

text: Air Canada Centre

text: <br>19,800| 35–35|- bgcolor="#bbffbb" | 71| March 26|

text: Detroit

text: Chris Bosh

text: Radoslav Nesterović

text: T. J. Ford

text: Air Canada Centre

text: <br>19,800| 36–35|- bgcolor="#bbffbb"| 72| March 28|

text: New York

text: Chris Bosh

text: Chris Bosh

text: Carlos Delfino

text: T. J. Ford

text: Air Canada Centre

text: <br>19,800| 37–35|- bgcolor="#ffcccc"| 73| March 30|

text: New Orleans

text: Chris Bosh

text: Chris Bosh

text: Kris Humphries

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 37–36|- bgcolor="#bbffbb" | 74| March 31| @

text: Charlotte

text: Chris Bosh

text: Radoslav Nesterović

text: T. J. Ford

text: Charlotte Bobcats Arena

text: <br>12,188| 38–36|- bgcolor="#ffcccc"| 75| April 2| @

text: Atlanta

text: Chris Bosh

text: Carlos Delfino

text: T. J. Ford

text: Philips Arena

text: <br>14,691| 38–37|- bgcolor="#ffcccc"| 76| April 4|

text: Charlotte

text: Chris Bosh

text: Radoslav Nesterović

text: Radoslav Nesterović

text: T. J. Ford

text: Air Canada Centre

text: <br>19,800| 38–38|- bgcolor="#ffcccc"| 77| April 5| @

text: New Jersey

text: Radoslav Nesterović

text: Radoslav Nesterović

text: Chris Bosh

text: Izod Center

text: <br>15,927| 38–39|- bgcolor="#bbffbb"| 78| April 9|

text: Milwaukee

text: Chris Bosh

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>18,569| 39–39|- bgcolor="#bbffbb"| 79| April 11|

text: New Jersey

text: Carlos Delfino

text: Chris Bosh

text: José Calderón

text: Air Canada Centre

text: <br>19,800| 40–39|- bgcolor="#ffcccc"| 80| April 13| @

text: Detroit

text: Chris Bosh

text: Chris Bosh

text: T. J. Ford

text: The Palace of Auburn Hills

text: <br>22,076| 40–40|- bgcolor="#bbffbb"| 81| April 14|

text: Miami

text: Radoslav Nesterović

text: Andrea Bargnani

text: Radoslav Nesterović

text: Anthony Parker

text: José Calderón

text: Air Canada Centre

text: <br>18,855| 41–40|- bgcolor="#ffcccc" | 82| April 16| @

text: Chicago

text: T. J. Ford

text: Kris Humphries

text: José Calderón

text: United Center

text: <br>21,909| 41–41

text: This shows the spring tide/ neap tide cycle in the amplitudes of the tides as the  moon orbits the earth from being in line (Sun - Earth - Moon, or Sun - Moon - Earth) when the two main influences combine to give the spring tides, to when the two forces are opposing each other as when the angle Moon - Earth - Sun is close to ninety degrees producing the neap tides. Note also as the moon moves around its orbit it also changes from north of the equator to south of the equator. The alternation in the heights of the high tides becomes smaller, until they are the same (the moon is above the equator), then redevelops but with the other polarity, waxing to a maximum difference and then waning again.

text: Because the Moon's mass is a considerable fraction of that of Earth (about 1:81), the two bodies can be regarded as a double planet system, rather than as a planet with a satellite.  The plane of the Moon's orbit around Earth lies close to the plane of Earth's orbit around the Sun (the ecliptic), rather than in the plane perpendicular to the axis of rotation of Earth (the equator) as is usually the case with planetary satellites.  The mass of the Moon is sufficiently large, and it is sufficiently close, to raise tides in the matter of Earth. In particular, the water of the oceans bulges out towards and away from the Moon. The average tidal bulge is synchronized with the Moon's orbit, and Earth rotates under this tidal bulge in just over a day. However, Earth's rotation drags the position of the tidal bulge ahead of the position directly under the Moon. As a consequence, there exists a substantial amount of mass in the bulge that is offset from the line through the centers of Earth and the Moon. Because of this offset, a portion of the gravitational pull between Earth's tidal bulges and the Moon is not perpendicular to the Earth–Moon line, i.e. there exists a torque between Earth and the Moon. This boosts the Moon in its orbit, and slows the rotation of Earth.

text: Because the

text: Moon

text: 's mass is a considerable fraction of that of Earth (about 1:81), the two bodies can be regarded as a

text: double planet

text: system, rather than as a planet with a satellite.  The plane of the Moon's

text: orbit

text: around Earth lies close to the plane of Earth's orbit around the Sun (the

text: ecliptic

text: ), rather than in the plane perpendicular to the axis of rotation of Earth (the

text: equator

text: ) as is usually the case with planetary satellites.  The mass of the Moon is sufficiently large, and it is sufficiently close, to raise

text: tide

text: s in the matter of Earth. In particular, the

text: water

text: of the

text: ocean

text: s bulges out towards and away from the Moon. The average tidal bulge is synchronized with the Moon's orbit, and Earth rotates under this tidal bulge in just over a

text: day

text: . However, Earth's rotation drags the position of the tidal bulge ahead of the position directly under the Moon. As a consequence, there exists a substantial amount of mass in the bulge that is offset from the line through the centers of Earth and the Moon. Because of this offset, a portion of the gravitational pull between Earth's tidal bulges and the Moon is not perpendicular to the Earth–Moon line, i.e. there exists a

text: torque

text: between Earth and the Moon. This boosts the Moon in its orbit, and slows the rotation of Earth.

text: Eclipses may occur when the Earth and the Moon are equal in value weight and mass with the Sun, and the shadow of one body cast by the Sun falls on the other.  So at new moon, when the Moon is in conjunction with the Sun, the Moon may pass in front of the Sun as seen from a narrow region on the surface of the Earth and cause a solar eclipse.  At full moon, when the Moon is in opposition to the Sun, the Moon may pass through the shadow of the Earth, and a lunar eclipse is visible from the night half of the Earth. Conjunction and opposition of the Moon together have a special name: syzygy (from Greek for "junction"), because of the importance of these lunar phases.

text: Eclipse

text: s may occur when the

text: Earth

text: and the

text: Moon

text: are equal in value weight and mass with the

text: Sun

text: , and the shadow of one body cast by the Sun falls on the other.  So at

text: new moon

text: , when the Moon is in

text: conjunction

text: with the Sun, the Moon may pass in front of the Sun as seen from a narrow region on the surface of the Earth and cause a

text: solar eclipse

text: .  At

text: full moon

text: , when the Moon is in

text: opposition

text: to the Sun, the Moon may pass through the shadow of the Earth, and a

text: lunar eclipse

text: is visible from the night half of the Earth. Conjunction and opposition of the Moon together have a special name:

text: syzygy

text: (from

text: Greek

text: for "junction"), because of the importance of these

text: lunar phase

text: s.

text: Lunar soil is the fine fraction of the regolith found on the surface of the Moon. Its properties can differ significantly from those of terrestrial soil. The physical properties of lunar soil are primarily the result of mechanical disintegration of basaltic and anorthositic rock, caused by continuous meteoric impact and bombardment by interstellar charged atomic particles over years. The process is largely one of mechanical weathering in which the particles are ground to finer and finer size over time. This situation contrasts fundamentally to terrestrial soil formation, mediated by the presence of molecular oxygen (O), humidity, atmospheric wind, and a robust array of contributing biological processes. Some have argued that the term "soil" is not correct in reference to the Moon because on the Earth, soil is defined as having organic content, whereas the Moon has none. However, standard usage among lunar scientists is to ignore that distinction.

text: Lunar soil is the fine fraction of the

text: regolith

text: found on the surface of the

text: Moon

text: . Its properties can differ significantly from those of terrestrial

text: soil

text: . The physical properties of lunar soil are primarily the result of mechanical disintegration of

text: basaltic

text: and

text: anorthositic

text: rock, caused by continuous meteoric impact and bombardment by interstellar charged atomic particles over years. The process is largely one of mechanical weathering in which the particles are ground to finer and finer size over time. This situation contrasts fundamentally to terrestrial soil formation, mediated by the presence of

text: molecular oxygen

text: (O), humidity, atmospheric wind, and a robust array of contributing biological processes. Some have argued that the term "soil" is not correct in reference to the Moon because on the

text: Earth

text: , soil is defined as having

text: organic

text: content, whereas the Moon has none. However, standard usage among lunar scientists is to ignore that distinction.

text: Recent measurements of the chemical composition of Moon rocks suggest that Earth was born with its water already present. Investigating lunar samples carried to Earth by the Apollo 15 and 17 missions found a deuterium-to-hydrogen ratio that matched the isotopic ratio in carbonaceous chondrites. The ratio is also similar to that found in water on Earth. The findings suggest a common source of water for both objects.  This supports a theory that Jupiter temporarily migrated into the inner Solar System, destabilizing the orbits of water-rich carbonaceous chondrites.  As a result, some of the bodies could have fallen inwards and become part of the raw material for making Earth and its neighbors. The discovery of water vapor out-gassing from Ceres provides related information on water-ice content of the asteroid belt.

text: The original Proto-Indo-European lunar deity appears to have been a male god. In subsequent traditions, the number of male moon deities (or words for "moon" with a male gender) seem to vastly outnumber female ones, which appear to be an exclusively eastern Mediterranean invention. Several goddesses, like Artemis or Hecate, did not originally have lunar aspects, and only acquired them late in antiquity, due to syncretism with Selene/Luna, the de facto Greco-Latin lunar deity. In traditions with male gods, there is little evidence of such syncretism, though the Greco-Roman Hermes has been equated with male Egyptian lunar gods like Thoth. In Greece proper, remnants of male moon gods are also seen with Menelaus.

text: The original

text: Proto-Indo-European

text: lunar deity appears to have been a male god. In subsequent traditions, the number of male moon deities (or words for "moon" with a male gender) seem to vastly outnumber female ones, which appear to be an exclusively eastern Mediterranean invention. Several goddesses, like

text: Artemis

text: or

text: Hecate

text: , did not originally have lunar aspects, and only acquired them late in antiquity, due to syncretism with

text: Selene

text: Luna

text: , the de facto Greco-Latin lunar deity. In traditions with male gods, there is little evidence of such syncretism, though the Greco-Roman

text: Hermes

text: has been equated with male Egyptian lunar gods like

text: Thoth

text: . In Greece proper, remnants of male moon gods are also seen with

text: Menelaus

text: Rotovators can thus be charged by momentum exchange. Momentum charging uses the rotovator to move mass from a place that is "higher" in a gravity field to a place that is "lower". The technique to do this uses the Oberth effect, where releasing the payload when the tether is moving with higher linear speed, lower in a gravitational potential gives more specific energy, and ultimately more speed than the energy lost picking up the payload at a higher gravitational potential, even if the rotation rate is the same. For example, it is possible to use a system of two or three rotovators to implement trade between the Moon and Earth. The rotovators are charged by lunar mass (dirt, if exports are not available) dumped on or near the Earth, and can use the momentum so gained to boost Earth goods to the Moon. The momentum and energy exchange can be balanced with equal flows in either direction, or can increase over time.

text: Rotovators can thus be charged by

text: momentum

text: exchange. Momentum charging uses the rotovator to move mass from a place that is "higher" in a

text: gravity field

text: to a place that is "lower". The technique to do this uses the

text: Oberth effect

text: , where releasing the payload when the tether is moving with higher linear speed, lower in a gravitational potential gives more

text: specific energy

text: , and ultimately more speed than the energy lost picking up the payload at a higher gravitational potential, even if the rotation rate is the same. For example, it is possible to use a system of two or three rotovators to implement trade between the

text: Moon

text: and

text: Earth

text: . The rotovators are charged by lunar mass (dirt, if exports are not available) dumped on or near the Earth, and can use the momentum so gained to boost Earth goods to the Moon. The momentum and energy exchange can be balanced with equal flows in either direction, or can increase over time.

text: Tides are controlled mainly by the gravitational pull of the moon. About once a day the moon rotates about the earth, attracting as it travels the bulge of water called the high tide that also travels round the earth. There are actually two high tides, because the earth and moon, as a system, both rotate about a common centre of mass. This centre is two-thirds out from the centre of the earth, not at the centre of the earth. The effect of the earth spinning about this centre is that it behaves as a centrifuge, resulting in a second high tide bulge in the ocean most distant from the moon.

text: Tide

text: s are controlled mainly by the

text: gravitational pull

text: of the moon. About once a day the moon rotates about the earth, attracting as it travels the bulge of water called the

text: high tide

text: that also travels round the earth. There are actually two high tides, because the earth and moon, as a system, both rotate about a common centre of mass. This centre is two-thirds out from the centre of the earth, not at the centre of the earth. The effect of the earth spinning about this centre is that it behaves as a centrifuge, resulting in a second high tide bulge in the ocean most distant from the moon.

text: Zernike is a lunar crater that is located on the far side of the Moon.

text: Zernike is a

text: lunar

text: crater

text: that is located on the

text: far side

text: of the

text: Moon

text: Protagonists Mario Esteban Rioz and Ted Long are Scavengers: Mars-born humans who scour space for the spent lower stages of spacecraft, which are then recycled on the Martian moon of Phobos. At the beginning of the story, Rioz scolds Long for wasting power listening to Grounder (Earth-born) politician John Hilder's argument that Earth's settlements on Mars, Venus, and the Moon are useless drains on Earth's economy, and that spaceships are wasting irreplaceable water by using it as reaction mass.

text: Protagonists Mario Esteban Rioz and Ted Long are Scavengers: Mars-born humans who scour space for the spent lower stages of spacecraft, which are then recycled on the Martian moon of Phobos. At the beginning of the story, Rioz scolds Long for wasting power listening to Grounder (Earth-born) politician John Hilder's argument that Earth's settlements on

text: Mars

text: Venus

text: , and the

text: Moon

text: are useless drains on Earth's economy, and that spaceships are wasting irreplaceable water by using it as

text: reaction mass

text: Generally, the Moon can be viewed even with the naked eye, however it may be more enjoyable with optical instruments. The primary lunar surface features detectable to the naked eye are the lunar maria or "seas", large basaltic plains which form imaginary figures as the traditional "Moon Rabbit" or familiar "Man in the Moon". The maria cover about 35% of the surface. The contrast between the less reflective dark gray maria and the more reflective gray/white lunar highlands is easily visible without optical aid. Under good viewing conditions, those with keen eyesight may also be able to see some of the following features:

text: Generally, the Moon can be viewed even with the naked eye, however it may be more enjoyable with optical instruments. The primary lunar surface features detectable to the naked eye are the

text: lunar maria

text: or "seas", large

text: basalt

text: ic plains which form imaginary figures as the traditional "

text: Moon Rabbit

text: " or familiar "

text: Man in the Moon

text: ". The maria cover about 35% of the surface. The contrast between the less reflective dark gray maria and the more reflective gray/white lunar highlands is easily visible without optical aid. Under good viewing conditions, those with keen eyesight may also be able to see some of the following features:

text: Geological studies of the Moon are based on a combination of Earth-based telescope observations, measurements from orbiting spacecraft, lunar samples, and geophysical data. Six locations were sampled directly during the manned Apollo program landings from 1969 to 1972, which returned  of lunar rock and soil to Earth. In addition, three robotic Soviet Luna spacecraft returned another  from 1970 to 1976. The Moon is the only extraterrestrial body for which we have samples with a known geologic context. A handful of lunar meteorites have been recognized on Earth, though their source craters on the Moon are unknown. A substantial portion of the lunar surface has not been explored, and a number of geological questions remain unanswered.

text: Geological

text: studies of the Moon are based on a combination of Earth-based

text: telescope

text: observations, measurements from

text: orbiting spacecraft

text: lunar samples

text: , and geophysical data. Six locations were sampled directly during the manned

text: Apollo program

text: landings from 1969 to 1972, which returned  of lunar rock and soil to Earth. In addition, three robotic

text: Soviet

text: Luna spacecraft

text: returned another  from 1970 to 1976. The Moon is the only extraterrestrial body for which we have samples with a known geologic context. A handful of

text: lunar meteorite

text: s have been recognized on Earth, though their source

text: craters

text: on the Moon are unknown. A substantial portion of the lunar surface has not been explored, and a number of geological questions remain unanswered.

text: In the second episode, Brian considers the nature of motion and explores how the celestial clockwork of the Sun and the Earth-Moon system account for a wide range of natural phenomena observed on Earth, from tropical cyclones and tidal waves to sunrises and seasonal changes. The episode begins in Warton Aerodrome in England with Brian taking to the air in a Eurofighter Typhoon, in an attempt to "beat the Earth's rotation and reverse the passage of the day." In Tacloban, Philippines, Brian narrates how the Coriolis force (caused by the Earth's spin) and the warmth of the tropical waters conspire to give rise to some of the deadliest storms in the world, like Typhoon Haiyan that hit the country in 2013.  Then, in Amapá, Brazil, he relates how the complex gravitational interaction between the Sun and the Moon are not just responsive for the gentle and familiar rise and fall of tides, but also for monstrous tidal bores, like the Pororoca on the waters of the Amazon. Towards the end, he lays out photographs from different points in his life – as a baby, getting married, with his own son, etc. – and concludes by stating that "if Einstein is right, then the past events we remember and our unforeseen future are all out there, somewhere in spacetime."

text: In the second episode, Brian considers the nature of motion and explores how the celestial clockwork of the Sun and the Earth-Moon system account for a wide range of natural phenomena observed on Earth, from

text: tropical cyclones

text: and

text: tidal waves

text: to

text: sunrises

text: and

text: seasonal changes

text: . The episode begins in

text: Warton Aerodrome

text: in

text: England

text: with Brian taking to the air in a

text: Eurofighter Typhoon

text: , in an attempt to "beat the Earth's rotation and reverse the passage of the day." In

text: Tacloban

text: Philippines

text: , Brian narrates how the

text: Coriolis force

text: (caused by the Earth's spin) and the warmth of the tropical waters conspire to give rise to some of the deadliest storms in the world, like

text: Typhoon Haiyan

text: that hit the country in 2013.  Then, in

text: Amapá

text: Brazil

text: , he relates how the complex gravitational interaction between the Sun and the Moon are not just responsive for the gentle and familiar rise and fall of tides, but also for monstrous tidal bores, like the

text: Pororoca

text: on the waters of the

text: Amazon

text: . Towards the end, he lays out photographs from different points in his life – as a baby, getting married, with his own son, etc. – and concludes by stating that "if

text: Einstein

text: is right, then the past events we remember and our unforeseen future are all out there, somewhere in

text: spacetime

text: The Moon used to rotate at a faster rate, but early in its history, its rotation slowed and became tidally locked in this orientation as a result of frictional effects associated with tidal deformations caused by Earth. With time, the energy of rotation of the Moon on its axis was dissipated as heat, until there was no rotation of the Moon relative to the Earth. The side of the Moon that faces Earth is called the near side, and the opposite the far side. The far side is often inaccurately called the "dark side", but it is in fact illuminated as often as the near side: once per lunar day, during the new moon phase we observe on Earth when the near side is dark. In 2016, planetary scientists, using data collected on the much earlier Nasa Lunar Prospector mission, found two hydrogen-rich areas on opposite sides of the Moon, probably in the form of water ice. It is speculated that these patches were the poles of the Moon billions of years ago, before it was tidally locked to Earth.

text: The Moon used to rotate at a faster rate, but early in its history, its rotation slowed and became

text: tidally locked

text: in this orientation as a result of

text: friction

text: al effects associated with

text: tidal

text: deformations caused by Earth. With time, the energy of rotation of the Moon on its axis was dissipated as heat, until there was no rotation of the Moon relative to the Earth. The side of the Moon that faces Earth is called the

text: near side

text: , and the opposite the

text: far side

text: . The far side is often inaccurately called the "dark side", but it is in fact illuminated as often as the near side: once per lunar day, during the new moon phase we observe on Earth when the near side is dark. In 2016, planetary scientists, using data collected on the much earlier Nasa

text: Lunar Prospector

text: mission, found two hydrogen-rich areas on opposite sides of the Moon, probably in the form of water ice. It is speculated that these patches were the poles of the Moon billions of years ago, before it was tidally locked to Earth.

text: Later the crater was nicknamed "the Monarch of the Moon" by lunar cartographer Thomas Gwyn Elger.

text: Later the crater was nicknamed "the Monarch of the Moon" by lunar cartographer

text: Thomas Gwyn Elger

text: Bae proposed a 4-staged developmental map towards interstellar flight. This would involve the Photonic Railway, a permanent energy-efficient transportation infrastructure based on Photonic Laser Thruster (PLT) in combination with Forward's model of beamed-laser propulsion (BLP), a PLT-BLP hybrid. This would reduce the cost and duration of interstellar commutes via proposed spacetrains.  The Stage-1 focuses on the near-earth space endeavors, such as orbit tuning, with Photonic Laser Thruster.  The Stage-2 focuses on Interlunar Photonic Railway between the earth and the moon.  The Stage-3 focuses on Interplanetary Photonic Railway between the earth and planets, moons and asteroids in the solar system.  The Stage-4 focuses on Interstellar Photonic Railway between the planets and moons of the solar system and those of other star systems.

text: A tide clock is a specially designed clock that keeps track of the Moon's apparent motion around the Earth. Along many coastlines the Moon contributes the major part (67 percent) of the combined lunar and solar tides. The exact interval between tides is influenced by the position of the Moon and Sun relative to the Earth as well as the specific location on earth where the tide is being measured. Owing to the Moon's orbital progress, it takes a particular point on the Earth (on average) 24 hours, 50.5 minutes to rotate under the Moon, so the time between high lunar tides fluctuates between 12 and 13 hours. A tide clock is divided into two six-hour-long tidal periods that shows the average length of time between high and low tide in a semi-diurnal tide region such as most areas of the Atlantic Ocean.  Therefore, compared with the actual time between the high lunar tides, tide clocks gain approximately 15 minutes per month and must be reset periodically.

text: A tide clock is a specially designed

text: clock

text: that keeps track of the Moon's apparent motion around the

text: Earth

text: . Along many coastlines the Moon contributes the major part (67 percent) of the combined lunar and solar

text: tide

text: s. The exact interval between tides is influenced by the position of the Moon and Sun relative to the Earth as well as the specific location on earth where the tide is being measured. Owing to the Moon's orbital progress, it takes a particular point on the Earth (on average) 24 hours, 50.5 minutes to rotate under the Moon, so the time between high lunar tides fluctuates between 12 and 13 hours. A tide clock is divided into two six-hour-long tidal periods that shows the average length of time between high and low tide in a

text: semi-diurnal

text: tide region such as most areas of the Atlantic Ocean.  Therefore, compared with the actual time between the high lunar tides, tide clocks gain approximately 15 minutes per month and must be reset periodically.

text: A small lunar crater is named after Daniel Barringer on the far side of the Moon.

text: A small lunar crater

text: is named after Daniel Barringer on the far side of the

text: Moon

text: Several lines of evidence imply that the lunar core is small, with a radius of about 350 km or less. The size of the lunar core is only about 20% the size of the Moon itself, in contrast to about 50% as is the case for most other terrestrial bodies. The composition of the lunar core is not well constrained, but most believe that it is composed of metallic iron alloyed with a small amount of sulfur and nickel. Analyses of the Moon's time-variable rotation indicate that the core is at least partly molten.

text: Several lines of evidence imply that the lunar core is small, with a radius of about 350 km or less. The size of the lunar core is only about 20% the size of the Moon itself, in contrast to about 50% as is the case for most other terrestrial bodies. The composition of the lunar core is not well constrained, but most believe that it is composed of metallic iron alloyed with a small amount of

text: sulfur

text: and

text: nickel

text: . Analyses of the Moon's time-variable rotation indicate that the core is at least partly molten.

text: This path (or limiting path) may not be unique: there may be many "shortest paths." Also, no path may exist; for example, suppose A lies in a black hole and B lies outside the black hole—since nothing can exit a black hole, such a path would not exist. Finally, because of general relativity, this path is not a "straight line" in the strict Euclidean sense, but is "curved." For example, if we aimed a rocket at the Moon traveling near the speed of light, the shortest path to the Moon is still a curved path. In fact, even if we aimed a photon of light at the Moon, it will follow a curved path, since gravity bends all things. The space along which the photon travels is, in fact, curved because gravity curves space itself.  Just like traveling along the surface of water; if the surface of the water is swelled in a wave, then it would still be possible to travel in a straight line through the water (traveling underneath the wave,) but it would require more effort than just traveling along the curved surface of the water.  It is still possible to travel in a straight line to the Moon, yet since the curved light beam is the best, the curved path close to this beam (following the path of the curved space) is better than the straight path.  This is because the light beam is technically actually traveling in a straight line, relative to the curved space it is traveling in, but the space itself is curved, so it appears to an outside observer that the light beam is traveling in a curved line.  Of course, if we take energy expenditures into account, then the minimum energy paths are just transfer orbits and gravity boosts that Earth space agencies predominantly use although these are not 'fast'.

text: This path (or limiting path) may not be unique: there may be many "shortest paths." Also, no path may exist; for example, suppose A lies in a

text: black hole

text: and B lies outside the black hole—since nothing can exit a black hole, such a path would not exist. Finally, because of

text: general relativity

text: The acceleration due to gravity on the surface of the Moon is 1.62519 m/s, about 16.6% that on Earth's surface or 0.16 . Over the entire surface, the variation in gravitational acceleration is about 0.0253 m/s (1.6% of the acceleration due to gravity). Because weight is directly dependent upon gravitational acceleration, things on the Moon will weigh only 16.6% of what they weigh on the Earth.

text: The acceleration due to gravity on the surface of the Moon is 1.62519 m/s, about 16.6% that on Earth's surface or 0.16

text: . Over the entire surface, the variation in gravitational acceleration is about 0.0253 m/s (1.6% of the acceleration due to gravity). Because

text: weight

text: is directly dependent upon gravitational acceleration, things on the Moon will weigh only 16.6% of what they weigh on the Earth.

text: Experiments with a mirror are used to show that the moon's surface must be opaque and not a perfect crystal sphere as Simplicio believes. He  refuses to accept that mountains on the moon cause shadows, or that reflected light from the earth is responsible for the faint outline in a crescent moon.

text: The lunar horizontal parallax at any time depends on the linear distance of the Moon from the Earth. The Earth–Moon linear distance varies continuously as the Moon follows its perturbed and approximately elliptical orbit around the Earth. The range of the variation in linear distance is from about 56 to 63.7 Earth radii, corresponding to horizontal parallax of about a degree of arc, but ranging from about 61.4' to about 54'. The Astronomical Almanac and similar publications tabulate the lunar horizontal parallax and/or the linear distance of the Moon from the Earth on a periodical e.g. daily basis for the convenience of astronomers (and formerly, of navigators), and the study of the way in which this coordinate varies with time forms part of lunar theory.

text: The lunar horizontal parallax at any time depends on the linear distance of the Moon from the Earth. The Earth–Moon linear distance varies continuously as the Moon follows its

text: perturbed and approximately elliptical orbit

text: around the Earth. The range of the variation in linear distance is from about 56 to 63.7 Earth radii, corresponding to horizontal parallax of about a degree of arc, but ranging from about 61.4' to about 54'. The

text: Astronomical Almanac

text: and similar publications tabulate the lunar horizontal parallax and/or the linear distance of the Moon from the Earth on a periodical e.g. daily basis for the convenience of astronomers (and formerly, of navigators), and the study of the way in which this coordinate varies with time forms part of

text: lunar theory

text: Pettit is a lunar impact crater that lies near the western limb of the Moon. In this location the crater is viewed nearly from the side by observers on Earth, and visibility can be significantly affected by libration effects.

text: Pettit is a

text: lunar

text: impact crater

text: that lies near the western limb of the

text: Moon

text: . In this location the crater is viewed nearly from the side by observers on

text: Earth

text: , and visibility can be significantly affected by

text: libration

text: effects.

text: Crookes is a lunar impact crater that lies on the Moon's far side as seen from the Earth. It lies just to the southwest of the giant crater Korolev. To the southwest of Crookes is McKellar.

text: Crookes is a

text: lunar

text: impact crater

text: that lies on the

text: Moon

text: 's

text: far side

text: as seen from the

text: Earth

text: . It lies just to the southwest of the giant crater

text: Korolev

text: . To the southwest of Crookes is

text: McKellar

text: Part II of the book, "From the Earth to the Moon," focuses on Earth's orbit and atmosphere and the Moon, with particular emphasis on how photon scattering results in the sky appearing blue, the impact of axial tilt on seasons, the impact of the Moon's presence, and misconceptions regarding the "Moon Size Illusion," explaining why and how the Moon appears larger when closer to the horizon.

text: Part II of the book, "From the Earth to the Moon," focuses on Earth's orbit and atmosphere and the Moon, with particular emphasis on how photon scattering results in the sky appearing blue, the impact of axial tilt on seasons, the impact of the Moon's presence, and misconceptions regarding the "

text: Moon Size Illusion

text: ," explaining why and how the Moon appears larger when closer to the horizon.

text: One such claim is based on an interpretation of the passage in the Quran which states: "Have not those who disbelieve known that the heavens and the earth were of one piece, then We parted them and we made every living thing of water? Will they not then believe?" Muslims claim that the first part of the verse is referring to the Big Bang and the second part of the verse refers to the fact that all living things are made of water since and water being a necessary component for life. The notion of "separation of heaven and earth" is common in several other creation stories, some of which preceded the Quran, such as Egyptian mythology, Sumerian mythology, Greek mythology, Hindu mythology, Japanese mythology and Maori mythology. Muslims also believe that the Quran also refers to the protective properties of the atmosphere when it says, "We made the sky a preserved and protected roof yet still they turn away from Our Signs." However, another verse of the Quran says that god withholds the sky from falling on the earth, "Seest thou not that God has made subject to you (men) all that is on the earth, and the ships that sail through the sea by His Command? He withholds the sky from falling on the earth except by His leave: for God is Most Kind and Most Merciful to man." Muslims also believe the Quran mentions the rotation and orbit of the Sun and the Moon when one of its verse states, "It is He who created the night and the day, and the sun, and the moon; each of them swim along in its rounded course." However, others claim that this Quran verse describes the sun and the moon in parallel orbits, as Quran verse 36:40 says, "It is not allowable for the sun to reach the moon, nor does the night overtake the day, but each, in an orbit, is swimming." However, understanding of the rotation and orbit of the Sun and the Moon, called Geocentrism, existed long before the Quran was written.

text: One such claim is based on an interpretation of the passage in the Quran which states: "Have not those who disbelieve known that the heavens and the earth were of one piece, then We parted them and we made every living thing of water? Will they not then believe?" Muslims claim that the first part of the verse is referring to the

text: Big Bang

text: and the second part of the verse refers to the fact that all living things are made of water since and water being a necessary component for life. The notion of "separation of heaven and earth" is common in several other creation stories, some of which preceded the Quran, such as

text: Egyptian mythology

text: Sumerian mythology

text: Greek mythology

text: Hindu mythology

text: Japanese mythology

text: and

text: Maori mythology

text: . Muslims also believe that the Quran also refers to the protective properties of the

text: atmosphere

text: when it says, "We made the sky a preserved and protected roof yet still they turn away from Our Signs." However, another verse of the Quran says that god withholds the sky from falling on the earth, "Seest thou not that God has made subject to you (men) all that is on the earth, and the ships that sail through the sea by His Command? He withholds the sky from falling on the earth except by His leave: for God is Most Kind and Most Merciful to man." Muslims also believe the Quran mentions the rotation and orbit of the

text: Sun

text: and the

text: Moon

text: when one of its verse states, "It is He who created the night and the day, and the sun, and the moon; each of them swim along in its rounded course." However, others claim that this Quran verse describes the sun and the moon in parallel orbits, as Quran verse 36:40 says, "It is not allowable for the sun to reach the moon, nor does the night overtake the day, but each, in an orbit, is swimming." However, understanding of the rotation and orbit of the

text: Sun

text: and the

text: Moon

text: , called

text: Geocentrism

text: , existed long before the Quran was written.

text: Riccioli and Grimaldi extensively studied the moon, of which Grimaldi drew maps. This material was included in Book 4 of the New Almagest. Grimaldi's maps were based on earlier work by Johannes Hevelius and Michael Van Langren. On one of these maps, Riccioli provided names for lunar features—names which are the basis for the nomenclature of lunar features still in use today. For example, Mare Tranquillitatis (The Sea of Tranquility, site of the Apollo 11 landing in 1969), received its name from Riccioli. Riccioli named large lunar areas for weather. He named craters for significant astronomers, grouping them by philosophies and time periods. Although Riccioli rejected the Copernican theory, he named a prominent lunar crater "Copernicus", and he named other important craters after other proponents of the Copernican theory such as Kepler, Galileo and Lansbergius. Because craters that he and Grimaldi named after themselves are in the same general vicinity as these, while craters named for some other Jesuit astronomers are in a different part of the Moon, near the very prominent crater named for Tycho Brahe, Riccioli's lunar nomenclature has at times been considered to be a tacit expression of sympathy for a Copernican theory that, as a Jesuit, he could not publicly support. However, Riccioli said he put the Copernicans all in stormy waters (the Oceanus Procellarum). Another noteworthy feature of the map is that Riccioli included on it a direct statement that the moon is not inhabited. This ran counter to speculations about an inhabited moon that had been present in the works of Nicholas of Cusa, Giordano Bruno, and even Kepler, and which would continue on in works of later writers such as Bernard de Fontenelle and William Herschel.

text: Riccioli and Grimaldi extensively studied the moon, of which Grimaldi drew maps. This material was included in Book 4 of the New Almagest. Grimaldi's maps were based on earlier work by Johannes Hevelius and Michael Van Langren. On one of these maps, Riccioli provided names for lunar features—names which are the basis for the nomenclature of lunar features still in use today. For example,

text: Mare Tranquillitatis

text: (The Sea of Tranquility, site of the Apollo 11 landing in 1969), received its name from Riccioli. Riccioli named large lunar areas for weather. He named craters for significant astronomers, grouping them by philosophies and time periods. Although Riccioli rejected the Copernican theory, he named a prominent lunar crater

text: "Copernicus"

text: , and he named other important craters after other proponents of the Copernican theory such as

text: Kepler

text: Galileo

text: and

text: Lansbergius

text: . Because craters that he and Grimaldi named after themselves are in the same general vicinity as these, while craters named for some other Jesuit astronomers are in a different part of the Moon, near the very prominent crater named for

text: Tycho

text: Brahe, Riccioli's lunar nomenclature has at times been considered to be a tacit expression of sympathy for a Copernican theory that, as a Jesuit, he could not publicly support. However, Riccioli said he put the Copernicans all in stormy waters (the Oceanus Procellarum). Another noteworthy feature of the map is that Riccioli included on it a direct statement that the moon is not inhabited. This ran counter to speculations about an inhabited moon that had been present in the works of Nicholas of Cusa, Giordano Bruno, and even Kepler, and which would continue on in works of later writers such as

text: Bernard de Fontenelle

text: and

text: William Herschel

text: There are two points in space where an elevator's docking port could maintain a stable, lunar-synchronous position: the Earth-Moon Lagrange points  and .  is 56,000 km away from the Earth-facing side of the Moon, (at the lunar equator) and  is 67,000 km from the center of the Moon's far side, in the exact opposite direction. At these points, the effect of the Moon's gravity and the effect of the centrifugal force resulting from the elevator system's synchronous, rigid body rotation cancel each other out.  The gravitational stability of these Lagrange points are not permanent, ( and  are in unstable equilibrium along a straight line between Earth and Moon,) but so long as small inertial adjustments are made to account for minor gravitational perturbations, any object positioned there can remain stationary.

text: There are two points in space where an elevator's docking port could maintain a stable, lunar-synchronous position: the Earth-Moon Lagrange points  and .  is 56,000 km away from the Earth-facing side of the Moon, (at the lunar equator) and  is 67,000 km from the center of the Moon's

text: far side

text: , in the exact opposite direction. At these points, the effect of the Moon's

text: gravity

text: and the effect of the

text: centrifugal force

text: resulting from the elevator system's synchronous,

text: rigid body

text: rotation cancel each other out.  The gravitational stability of these Lagrange points are not permanent, ( and  are in unstable equilibrium along a straight line between Earth and Moon,) but so long as small inertial adjustments are made to account for minor gravitational perturbations, any object positioned there can remain stationary.

text: One way to determine the lunar parallax from one location is by using a lunar eclipse. A full shadow of the Earth on the Moon has an apparent radius of curvature equal to the difference between the apparent radii of the Earth and the Sun as seen from the Moon. This radius can be seen to be equal to 0.75 degree, from which (with the solar apparent radius 0.25 degree) we get an Earth apparent radius of 1 degree. This yields for the Earth–Moon distance 60.27 Earth radii or  This procedure was first used by Aristarchus of Samos and Hipparchus, and later found its way into the work of Ptolemy. The diagram at right shows how daily lunar parallax arises on the geocentric and geostatic planetary model in which the Earth is at the centre of the planetary system and does not rotate. It also illustrates the important point that parallax need not be caused by any motion of the observer, contrary to some definitions of parallax that say it is, but may arise purely from motion of the observed.

text: One way to determine the lunar parallax from one location is by using a lunar eclipse. A full shadow of the Earth on the Moon has an apparent radius of curvature equal to the difference between the apparent radii of the Earth and the Sun as seen from the Moon. This radius can be seen to be equal to 0.75 degree, from which (with the solar apparent radius 0.25 degree) we get an Earth apparent radius of 1 degree. This yields for the Earth–Moon distance 60.27 Earth radii or  This procedure was first used by

text: Aristarchus of Samos

text: and

text: Hipparchus

text: , and later found its way into the work of

text: Ptolemy

text: . The diagram at right shows how daily lunar parallax arises on the geocentric and geostatic planetary model in which the Earth is at the centre of the planetary system and does not rotate. It also illustrates the important point that parallax need not be caused by any motion of the observer, contrary to some definitions of parallax that say it is, but may arise purely from motion of the observed.

text: There are three main components to the Team FREDNET mission which include (a) the transfer mission (i.e. getting the rover from the Earth to the Moon), (b) the Moon mission (i.e. directing the rover to accomplish the tasks needed to win the Google Lunar X-Prize), and (c) the Earth mission (i.e. receiving the data that the rover must transmit to Earth to win the Google Lunar X PRIZE).

text: Water vapor is a significant component of the Earth's atmosphere and a greenhouse gas. It is also common in the Solar System and by extension, other planetary systems. Its signature has been detected in the atmospheres of the Sun, occurring in sunspots. The presence of water vapor has been detected in the atmospheres of Mercury, Venus, Earth (and Moon), Mars, Jupiter, Saturn, Uranus and Neptune, the planets of the Solar System, although typically in only trace amounts.

text: Water vapor is a significant component of the Earth's atmosphere and a greenhouse gas. It is also common in the

text: Solar System

text: and by extension, other

text: planetary system

text: s. Its signature has been detected in the atmospheres of the Sun, occurring in

text: sunspots

text: . The presence of water vapor has been detected in the atmospheres of Mercury, Venus, Earth (and Moon), Mars, Jupiter, Saturn, Uranus and Neptune, the planets of the Solar System, although typically in only trace amounts.

text: A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth, and moon are aligned (in "syzygy") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can occur only the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes.

text: A lunar eclipse occurs when the

text: Moon

text: passes directly behind the

text: Earth

text: into its

text: umbra

text: (shadow). This can occur only when the sun, Earth, and moon are aligned (in "

text: syzygy

text: ") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can occur only the night of a

text: full moon

text: . The type and length of an

text: eclipse

text: depend upon the Moon's location relative to its

text: orbital node

text: s.

text: A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the Sun, Earth, and Moon are aligned (in "syzygy") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes.

text: A

text: lunar eclipse

text: occurs when the

text: Moon

text: passes directly behind the

text: Earth

text: into its

text: umbra

text: (shadow). This can occur only when the Sun, Earth, and Moon are aligned (in "

text: syzygy

text: ") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a

text: full moon

text: . The type and length of an

text: eclipse

text: orbital node

text: s.

text: Waters has also regularly included it on his solo tours. For his tour supporting The Pros and Cons of Hitch Hiking, he sang the lead vocals himself. For his Radio K.A.O.S. tour, guest vocalist and keyboardist Paul Carrack sung the lead. For the American part of his In the Flesh tour, it was sung by Doyle Bramhall II, while for the European part it was sung by Chester Kamen. For The Dark Side of the Moon Live, it was sung by Dave Kilminster. "Money" was also performed by Waters at Live Earth's Concert at Giants Stadium on 7 July 2007.

text: Waters has also regularly included it on his solo tours. For his tour supporting

text: The Pros and Cons of Hitch Hiking

text: , he sang the lead vocals himself. For his

text: Radio K.A.O.S.

text: tour, guest vocalist and keyboardist

text: Paul Carrack

text: sung the lead. For the American part of his

text: In the Flesh

text: tour, it was sung by

text: Doyle Bramhall II

text: , while for the European part it was sung by

text: Chester Kamen

text: . For

text: The Dark Side of the Moon Live

text: , it was sung by

text: Dave Kilminster

text: . "Money" was also performed by Waters at

text: Live Earth

text: 's

text: Concert at Giants Stadium

text: on 7 July 2007.

text: So, clearly these bodies are well outside their Roche limits by various factors, from 21 for the Moon (over its fluid-body Roche limit) as part of the Earth–Moon system, upwards to thousands for Earth and Jupiter.

text: As seen from the Earth, a solar eclipse is a type of eclipse that occurs when the Moon passes between the Sun and Earth, and the Moon fully or partially blocks ("occults") the Sun. This can happen only at new moon when the Sun and the Moon are in conjunction as seen from Earth in an alignment referred to as syzygy. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses, only part of the Sun is obscured.

text: As seen from the

text: Earth

text: , a solar eclipse is a type of

text: eclipse

text: that occurs when the

text: Moon

text: passes between the

text: Sun

text: and Earth, and the Moon fully or partially blocks ("

text: occults

text: ") the Sun. This can happen only at

text: new moon

text: when the Sun and the Moon are in

text: conjunction

text: as seen from Earth in an alignment referred to as

text: syzygy

text: . In a total

text: eclipse

text: , the disk of the Sun is fully obscured by the Moon. In

text: partial and annular eclipses

text: , only part of the Sun is obscured.

text: A lighthouse keeper named Basil Elton engages upon a peculiar fantasy in which a robed, bearded man is piloting a mystical white ship which appears when the moon is full. Elton walks out across the water on a bridge of moonbeams and joins the bearded man on this ship, and together they explore a mystical chain of islands unlike anything that can be found on Earth.

text: A lighthouse keeper named

text: Basil Elton

text: engages upon a peculiar fantasy in which a robed, bearded man is piloting a mystical white ship which appears when the moon is full. Elton walks out across the water on a bridge of moonbeams and joins the bearded man on this ship, and together they explore a mystical chain of islands unlike anything that can be found on Earth.

text: The dark areas visible on Earth's moon, the lunar maria, are plains of flood basaltic lava flows. These rocks were sampled by the manned American Apollo program, the robotic Russian Luna program, and are represented among the lunar meteorites.

text: The dark areas visible on Earth's

text: moon

text: , the

text: lunar maria

text: , are plains of

text: flood basalt

text: ic lava flows. These rocks were sampled by the manned American

text: Apollo program

text: , the robotic Russian

text: Luna program

text: , and are represented among the

text: lunar meteorites

text: Due to the synchronous rotation of the Moon about the Earth, Earthrise is not generally visible from the lunar surface. Earthrise is generally only visible when orbiting the Moon, other than at selected places near the Moon's limb, where libration carries the Earth slightly above and below the lunar horizon.

text: Due to the

text: synchronous rotation

text: of the Moon about the Earth, Earthrise is not generally visible from the lunar surface. Earthrise is generally only visible when orbiting the Moon, other than at selected places near the Moon's

text: limb

text: , where

text: libration

text: carries the Earth slightly above and below the lunar horizon.

text: Cruithne is mentioned on the QI season 1 episode "Astronomy", in which it is incorrectly described as a second moon of Earth. In a later episode, this mistake was rectified and it was added that earth has over 18,000 mini-moons.

text: Cruithne is mentioned on the

text: QI

text: season 1 episode "Astronomy", in which it is incorrectly described as a second moon of Earth. In a later episode, this mistake was rectified and it was added that earth has over 18,000 mini-moons.

text: The smallest craters found have been microscopic in size, found in rocks returned to Earth from the Moon.  The largest crater called such is about 290 kilometres (181 mi) across in diameter, located near the lunar South Pole. However, it is believed that many of the lunar maria were formed by giant impacts, with the resulting depression filled by upwelling lava .

text: The smallest craters found have been microscopic in size, found in rocks returned to Earth from the Moon.  The largest crater called such is about 290 kilometres (181 mi) across in diameter, located near the lunar South Pole. However, it is believed that many of the

text: lunar maria

text: were formed by giant impacts, with the resulting depression filled by upwelling

text: lava

text: Every human language has its own word for the Earth's Moon, and these words are the ones normally used in astronomical contexts. However, a number of fanciful or mythological names for the Moon have been used in the context of astronomy (an even larger number of lunar epithets have been used in non-astronomical contexts). In the 17th century, the Moon was sometimes referred to as Proserpina. More recently, especially in science-fictional contexts, the Moon has been called by the Latin name Luna, presumably on the analogy of the Latin names of the planets, or by association with the adjectival form lunar. In technical terminology, the word-stems seleno- (from Greek selēnē "moon") and cynthi- (from Cynthia, an epithet of the goddess Artemis) are sometimes used to refer to the Moon, as in selenography, selenology, and pericynthion.

text: Every human language has its own word for the Earth's

text: Moon

text: , and these words are the ones normally used in astronomical contexts. However, a number of fanciful or mythological names for the Moon have been used in the context of astronomy (an even larger number of lunar epithets have been used in non-astronomical contexts). In the 17th century, the Moon was sometimes referred to as Proserpina. More recently, especially in science-fictional contexts, the Moon has been called by the

text: Latin

text: name Luna, presumably on the analogy of the Latin names of the planets, or by association with the adjectival form lunar. In technical terminology, the word-stems seleno- (from

text: Greek

text: selēnē "moon") and cynthi- (from Cynthia, an epithet of the goddess

text: Artemis

text: ) are sometimes used to refer to the Moon, as in selenography, selenology, and pericynthion.

text: California Grunion fish have an unusual mating and spawning ritual during the spring and summer months.  The egg laying takes place on four consecutive nights, beginning on the nights of the full and new Moons, when tides are highest.  However, this is a well understood reproductive strategy that is more related to tides than it is to lunar phase.  It happens to correlate with the lunar phase because tides are highest when the Sun, Earth, and Moon are aligned, i.e., at new Moon or full Moon.

text: California Grunion

text: fish have an unusual mating and spawning ritual during the spring and summer months.  The egg laying takes place on four consecutive nights, beginning on the nights of the full and new Moons, when tides are highest.  However, this is a well understood reproductive strategy that is more related to tides than it is to lunar phase.  It happens to correlate with the lunar phase because tides are highest when the Sun, Earth, and Moon are aligned, i.e., at new Moon or full Moon.

text: The earthquake generated a seismic oscillation of the Earth's surface of up to , equivalent to the effect of the tidal forces caused by the Sun and Moon. The shock waves of the earthquake were felt across the planet; as far away as the U.S. state of Oklahoma, where vertical movements of  were recorded. By February 2005, the earthquake's effects were still detectable as a  complex harmonic oscillation of the Earth's surface, which gradually diminished and merged with the incessant free oscillation of the Earth more than 4 months after the earthquake.

text: The earthquake generated a seismic oscillation of the Earth's surface of up to , equivalent to the effect of the

text: tidal forces

text: caused by the Sun and Moon. The shock waves of the earthquake were felt across the planet; as far away as the U.S. state of

text: Oklahoma

text: , where vertical movements of  were recorded. By February 2005, the earthquake's effects were still detectable as a  complex harmonic oscillation of the Earth's surface, which gradually diminished and merged with the incessant free oscillation of the Earth more than 4 months after the earthquake.

text: It might be expected that once every month, when the Moon passes between Earth and the Sun during a new moon, its shadow would fall on Earth causing a solar eclipse, but this does not happen every month. Nor is it true that during every full moon, the Earth's shadow falls on the Moon, causing a lunar eclipse. Solar and lunar eclipses are not observed every month because the plane of the Moon's orbit around the Earth is tilted by about five degrees with respect to the plane of Earth's orbit around the Sun (the plane of the ecliptic). Thus, when new and full moons occur, the Moon usually lies to the north or south of a direct line through the Earth and Sun.  Although an eclipse can only occur when the Moon is either new (solar) or full (lunar), it must also be positioned very near the intersection of Earth's orbit plane about the Sun and the Moon's orbit plane about the Earth (that is, at one of its nodes).  This happens about twice per year, and so there are between four and seven eclipses in a calendar year. Most of these events are quite insignificant; major eclipses of the Moon or Sun are less frequent.

text: It might be expected that once every month, when the Moon passes between Earth and the Sun during a new moon, its shadow would fall on Earth causing a

text: solar eclipse

text: , but this does not happen every month. Nor is it true that during every full moon, the Earth's shadow falls on the Moon, causing a

text: lunar eclipse

text: . Solar and lunar eclipses are not observed every month because the plane of the Moon's orbit around the Earth is tilted by about five degrees with respect to the plane of Earth's orbit around the Sun (the

text: plane of the ecliptic

text: ). Thus, when new and full moons occur, the Moon usually lies to the north or south of a direct line through the Earth and Sun.  Although an

text: eclipse

text: can only occur when the Moon is either new (solar) or full (lunar), it must also be positioned very near the intersection of Earth's orbit plane about the Sun and the Moon's orbit plane about the Earth (that is, at one of its

text: node

text: s).  This happens about twice per year, and so there are between four and seven eclipses in a calendar year. Most of these events are quite insignificant; major eclipses of the Moon or Sun are less frequent.

text: The lunar maria represent ancient flood basaltic eruptions. In comparison to terrestrial lavas, these contain higher iron abundances, have low viscosities, and some contain highly elevated abundances of the titanium-rich mineral ilmenite. The majority of basaltic eruptions occurred between about 3 and 3.5 Ga ago, though some mare samples have ages as old as 4.2 Ga, and the youngest (based on the method of crater counting) are believed to have erupted only 1 billion years ago. Along with mare volcanism came pyroclastic eruptions, which launched molten basaltic materials hundreds of kilometres away from the volcano. A large portion of the mare formed, or flowed into, the low elevations associated with the nearside impact basins. However, Oceanus Procellarum does not correspond to any known impact structure, and the lowest elevations of the Moon within the farside South Pole-Aitken basin are only modestly covered by mare (see lunar mare for a more detailed discussion).Impacts by meteorites and comets are the only abrupt geologic force acting on the Moon today, though the variation of Earth tides on the scale of the Lunar anomalistic month causes small variations in stresses. Some of the most important craters used in lunar stratigraphy formed in this recent epoch. For example, the crater Copernicus, which has a depth of 3.76 km and a radius of 93 km, is believed to have formed about 900 million years ago (though this is debatable). The Apollo 17 mission landed in an area in which the material coming from the crater Tycho might have been sampled. The study of these rocks seem to indicate that this crater could have formed 100 million years ago, though this is debatable as well. The surface has also experienced space weathering due to high energy particles, solar wind implantation, and micrometeorite impacts. This process causes the ray systems associated with young craters to darken until it matches the albedo of the surrounding surface. However, if the composition of the ray is different from the underlying crustal materials (as might occur when a "highland" ray is emplaced on the mare), the ray could be visible for much longer times.

text: The

text: lunar maria

text: represent ancient flood basaltic eruptions. In comparison to terrestrial lavas, these contain higher iron abundances, have low viscosities, and some contain highly elevated abundances of the

text: titanium

text: -rich mineral

text: ilmenite

text: . The majority of

text: basalt

text: ic eruptions occurred between about 3 and 3.5 Ga ago, though some mare samples have ages as old as 4.2 Ga, and the youngest (based on the method of crater counting) are believed to have erupted only 1 billion years ago. Along with mare volcanism came

text: pyroclastic eruptions

text: , which launched molten basaltic materials hundreds of kilometres away from the

text: volcano

text: . A large portion of the mare formed, or flowed into, the low elevations associated with the nearside impact basins. However,

text: Oceanus Procellarum

text: does not correspond to any known impact structure, and the lowest elevations of the Moon within the farside

text: South Pole-Aitken basin

text: are only modestly covered by mare (see

text: lunar mare

text: for a more detailed discussion).Impacts by

text: meteorite

text: s and

text: comet

text: s are the only abrupt geologic force acting on the Moon today, though the variation of Earth tides on the scale of the Lunar

text: anomalistic month

text: causes small variations in stresses. Some of the most important

text: crater

text: s used in lunar stratigraphy formed in this recent epoch. For example, the crater

text: Copernicus

text: , which has a depth of 3.76 km and a radius of 93 km, is believed to have formed about 900 million years ago (though this is debatable). The

text: Apollo 17

text: mission landed in an area in which the material coming from the crater

text: Tycho

text: might have been sampled. The study of these rocks seem to indicate that this crater could have formed 100 million years ago, though this is debatable as well. The surface has also experienced

text: space weathering

text: due to high energy particles,

text: solar wind

text: implantation, and

text: micrometeorite

text: impacts. This process causes the

text: ray system

text: s associated with young craters to darken until it matches the albedo of the surrounding surface. However, if the composition of the ray is different from the underlying crustal materials (as might occur when a "highland" ray is emplaced on the mare), the ray could be visible for much longer times.

text: Hugh Klein was an American Astronaut on Apollo XXV, the last manned Moon mission. While on the Moon, Hugh discovered an ancient structure, thereafter referred to as the 'Lunar Villa'. Inside, Hugh finds an infant girl in a cradle, and is then confronted by a ghostly consortium identified as The Hundred. Caelius, speaker for the Hundred, explained how they were a group of scholars and philosophers devoted to peace who fled Rome during the time of the emperors. Using alchemical processes, they created the Lunar Villa and attempted to create a champion of their peaceful ideas on Earth. Unfortunately, they accidentally created the villain known as Valkus, the Centurion instead. To atone for this mistake, and to perpetuate their beliefs, they created a child they called the Praemonstra Supra, meaning "She Who Will Point the Way'. Hugh returned to Earth with the infant child, and he and his new wife, Jenny, were allowed to adopt and raise the infant, whom they named Laura.

text: Hugh Klein was an

text: American

text: Astronaut

text: on Apollo XXV, the last manned

text: Moon

text: mission. While on the Moon, Hugh discovered an ancient structure, thereafter referred to as the 'Lunar Villa'. Inside, Hugh finds an infant girl in a cradle, and is then confronted by a ghostly consortium identified as The Hundred. Caelius, speaker for the Hundred, explained how they were a group of scholars and philosophers devoted to peace who fled

text: Rome

text: during the time of the emperors. Using

text: alchemical

text: processes, they created the Lunar Villa and attempted to create a champion of their peaceful ideas on

text: Earth

text: . Unfortunately, they accidentally created the villain known as Valkus, the Centurion instead. To atone for this mistake, and to perpetuate their beliefs, they created a child they called the Praemonstra Supra, meaning "She Who Will Point the Way'. Hugh returned to Earth with the infant child, and he and his new wife, Jenny, were allowed to adopt and raise the infant, whom they named Laura.

text: The lunar (horizontal) parallax can alternatively be defined as the angle subtended at the distance of the Moon by the radius of the Earth—equal to angle p in the diagram when scaled-down and modified as mentioned above.

text: The Moon orbits the Earth in the same direction as the Earth rotates on its axis, so it takes slightly more than a day—about 24 hours and 50 minutes—for the Moon to return to the same location in the sky. During this time, it has passed overhead (culmination) once and underfoot once (at an hour angle of 00:00 and 12:00 respectively), so in many places the period of strongest tidal forcing is the above-mentioned, about 12 hours and 25 minutes. The moment of highest tide is not necessarily when the Moon is nearest to zenith or nadir, but the period of the forcing still determines the time between high tides.

text: The Moon orbits the Earth in the same direction as the Earth rotates on its axis, so it takes slightly more than a day—about 24 hours and 50 minutes—for the Moon to return to the same location in the sky. During this time, it has passed overhead (

text: culmination

text: ) once and underfoot once (at an

text: hour angle

text: of 00:00 and 12:00 respectively), so in many places the period of strongest tidal forcing is the above-mentioned, about 12 hours and 25 minutes. The moment of highest tide is not necessarily when the Moon is nearest to

text: zenith

text: or

text: nadir

text: , but the period of the forcing still determines the time between high tides.

text: The physics modeled included the mutual Newtonian gravitational accelerations and their relativistic corrections (a modified form of the Einstein-Infeld-Hoffmann equation), the accelerations caused by the tidal distortion of the Earth, the accelerations caused by the figure of the Earth and Moon, and a model of the lunar librations.

text: The physics modeled included the mutual

text: Newtonian

text: gravitational accelerations and their

text: relativistic corrections

text: (a modified form of the

text: Einstein-Infeld-Hoffmann equation

text: ), the

text: accelerations caused by the tidal distortion

text: of the Earth, the accelerations caused by the

text: figure of the Earth

text: and Moon, and a model of the lunar

text: libration

text: s.

text: To reduce the cost of transport, the Moon could store propellants produced from lunar water at one or several depots between the Earth and the Moon, to resupply rockets or satellites in Earth orbit. The Shackleton Energy Company estimate investment in this infrastructure could cost around $25 billion.

text: To reduce the cost of transport, the Moon could store

text: propellants produced from lunar water

text: at one or several

text: depots

text: between the Earth and the Moon, to resupply rockets or satellites in Earth orbit. The

text: Shackleton Energy Company

text: estimate investment in this infrastructure could cost around $25 billion.

text: Thundarr the Barbarian is set in a future (3994 AD) post-apocalyptic wasteland divided into kingdoms or territories — the majority of which are ruled by wizards – and whose ruins typically feature recognizable geographical features from the United States, starting in New York City and working itself to Los Angeles, Las Vegas, Mount Rushmore, San Francisco and Washington, D.C.. Other episodes with recognizable settings are located in Mexico, while one is in London. Another notable feature of this future Earth is that the Moon was broken in two pieces. The shattered moon and the ruins of the former human civilization were caused by the passage of a runaway planet between the Earth and the Moon in 1994, which, from scenes shown in the opening sequence, caused radical changes in the Earth's climate and geography. However, by the time period in which the series is set, the Earth and Moon seem to have settled into a new balance. Earth is reborn in a world of "savagery, super-science, and sorcery".

text: Thundarr the Barbarian is set in a future (3994 AD)

text: post-apocalyptic

text: wasteland divided into kingdoms or territories — the majority of which are ruled by

text: wizards

text: – and whose

text: ruins

text: typically feature recognizable geographical features from the

text: United States

text: , starting in

text: New York City

text: and working itself to

text: Los Angeles

text: Las Vegas

text: Mount Rushmore

text: San Francisco

text: and

text: Washington, D.C.

text: . Other episodes with recognizable settings are located in

text: Mexico

text: , while one is in

text: London

text: . Another notable feature of this future

text: Earth

text: is that the

text: Moon

text: was broken in two pieces. The shattered moon and the ruins of the former human civilization were caused by the passage of a runaway planet between the Earth and the Moon in 1994, which, from scenes shown in the opening sequence, caused radical changes in the Earth's climate and geography. However, by the time period in which the series is set, the Earth and Moon seem to have settled into a new balance. Earth is reborn in a world of "savagery, super-science, and sorcery".

text: The Earth subtends an angle of about two degrees, when seen from the Moon. This means that an observer on Earth who sees the Moon when it is close to the eastern horizon sees it from an angle that is about two degrees different from the line of sight of an observer who sees the Moon on the western horizon. The Moon moves about 12 degrees around its orbit per day, so, if these observers were stationary, they would see the phases of the Moon at times that differ by about one-sixth of a day, or four hours. But in reality the observers are on the surface of the rotating Earth, so someone who sees the Moon on the eastern horizon at one moment sees it on the western horizon about 12 hours later. This adds an oscillation to the apparent progression of the lunar phases. They appear to occur more slowly when the Moon is high in the sky than when it is below the horizon. The Moon appears to move jerkily, and the phases do the same. The amplitude of this oscillation is never more than about four hours, which is a small fraction of a month. It does not have any obvious effect on the appearance of the Moon. However, it does affect accurate calculations of the times of lunar phases.

text: Von Békésy is a worn lunar crater on the far side of the Moon. It is located in the northern latitudes, behind the northeastern limb of the Moon as seen from the Earth. This is a relatively isolated crater formation, the closest named crater being Volterra, just over one crater diameter to the north-northeast. To the southwest lies Millikan.

text: Von Békésy is a worn

text: lunar

text: crater

text: on the

text: far side

text: of the

text: Moon

text: . It is located in the northern latitudes, behind the northeastern limb of the Moon as seen from the

text: Earth

text: . This is a relatively isolated crater formation, the closest named crater being

text: Volterra

text: , just over one crater diameter to the north-northeast. To the southwest lies

text: Millikan

text: A lunar day is the period of time it takes for the Earth's Moon to complete one full rotation on its axis with respect to the Sun. Equivalently, it is the time it takes the Moon to make one complete orbit around the Earth and come back to the same phase. It is marked from a new moon to the next new moon.

text: A lunar day is the period of time it takes for the

text: Earth's Moon

text: to complete one full rotation on its

text: axis

text: with respect to the

text: Sun

text: . Equivalently, it is the time it takes the Moon to make one complete

text: orbit

text: around the

text: Earth

text: and come back to the same

text: phase

text: . It is marked from a

text: new moon

text: to the next new moon.

text: On 21 July 1969, while Apollo 11 astronauts finished the first human moonwalk, Luna 15, an unmanned Soviet spacecraft in lunar orbit at the time, began its descent to the lunar surface.  Launched three days before the Apollo 11 mission, it was the second Soviet attempt to return lunar soil back to Earth with a goal to outstrip the US in sample return under Moon race. The Soviet craft crashed into the Moon at 15:50 UT, hours before the scheduled American lift off from the Moon.

text: On 21 July 1969, while

text: Apollo 11

text: astronauts finished the first human moonwalk, Luna 15, an unmanned Soviet spacecraft in lunar orbit at the time, began its descent to the

text: lunar surface

text: .  Launched three days before the Apollo 11 mission, it was the second Soviet attempt to

text: return lunar soil back to Earth

text: with a goal to outstrip the US in sample return under

text: Moon race

text: . The Soviet craft crashed into the

text: Moon

text: at 15:50 UT, hours before the scheduled American lift off from the Moon.

text: An eclipse season is the only time during which the Sun (from the perspective of the Earth) is close enough to one of the Moon's nodes to allow for an eclipse to occur. During the season, whenever there is a full moon a lunar eclipse will occur and whenever there is a new moon a solar eclipse will occur. If the Sun is close enough to a node, then a total eclipse will occur. Each season lasts from 31 to 37 days, recurring about every 6 months. At least two (one solar and one lunar, in any order), and at most three eclipses (solar, lunar, then solar again, or vice versa), will occur during every eclipse season. This is because it is about 15 days (a fortnight) between full moon and new moon and vice versa. If there is an eclipse at the very beginning of the season, then there is enough time (30 days) for two more eclipses.

text: An eclipse season is the only time during which the Sun (from the perspective of the Earth) is close enough to one of the

text: Moon's nodes

text: to allow for an

text: eclipse

text: to occur. During the season, whenever there is a full moon a

text: lunar

text: eclipse will occur and whenever there is a new moon a

text: solar eclipse

text: will occur. If the Sun is close enough to a node, then a

text: total eclipse

text: will occur. Each season lasts from 31 to 37 days, recurring about every 6 months. At least two (one solar and one lunar, in any order), and at most three eclipses (solar, lunar, then solar again, or vice versa), will occur during every eclipse season. This is because it is about 15 days (a

text: fortnight

text: ) between full moon and new moon and vice versa. If there is an eclipse at the very beginning of the season, then there is enough time (30 days) for two more eclipses.

text: Scott is a lunar impact crater near the south pole of the Moon. Its location close to the lunar limb hinders observation, both from the foreshortening of the crater as seen from Earth and from the limited sunlight that enters the basin. In fact the northern end of this crater is in near perpetual darkness, and has not been mapped in detail. Scott lies between the similar-sized crater Amundsen to the southeast and Schomberger to the northwest. Just to the northeast is the crater Demonax.

text: Scott is a

text: lunar

text: impact crater

text: near the south pole of the

text: Moon

text: . Its location close to the lunar limb hinders observation, both from the foreshortening of the crater as seen from

text: Earth

text: and from the limited sunlight that enters the basin. In fact the northern end of this crater is in near perpetual darkness, and has not been mapped in detail. Scott lies between the similar-sized crater

text: Amundsen

text: to the southeast and

text: Schomberger

text: to the northwest. Just to the northeast is the crater

text: Demonax

text: The current model of the interior of the Moon was derived using seismometers left behind during the manned Apollo program missions, as well as investigations of the Moon's gravity field and rotation.

text: The current model of the interior of the Moon was derived using

text: seismometer

text: s left behind during the manned Apollo program missions, as well as investigations of the Moon's gravity field and rotation.

text: Priestley is a lunar crater that is located on the far side of the Moon from the Earth, in the low southern latitudes. It lies to the southeast of the flooded crater Kugler.

text: Priestley is a

text: lunar

text: crater

text: that is located on the

text: far side

text: of the

text: Moon

text: from the

text: Earth

text: , in the low southern

text: latitude

text: s. It lies to the southeast of the flooded crater

text: Kugler

text: Liquid water cannot persist on the lunar surface. When exposed to solar radiation, water quickly decomposes through a process known as photodissociation and is lost to space. However, since the 1960s, scientists have hypothesized that water ice may be deposited by impacting comets or possibly produced by the reaction of oxygen-rich lunar rocks, and hydrogen from solar wind, leaving traces of water which could possibly survive in cold, permanently shadowed craters at either pole on the Moon. Computer simulations suggest that up to  of the surface may be in permanent shadow. The presence of usable quantities of water on the Moon is an important factor in rendering lunar habitation as a cost-effective plan; the alternative of transporting water from Earth would be prohibitively expensive.

text: Liquid water cannot persist on the lunar surface. When exposed to solar radiation, water quickly decomposes through a process known as

text: photodissociation

text: and is lost to space. However, since the 1960s, scientists have hypothesized that water ice may be deposited by impacting

text: comets

text: or possibly produced by the reaction of oxygen-rich lunar rocks, and hydrogen from

text: solar wind

text: , leaving traces of water which could possibly survive in cold, permanently shadowed craters at either pole on the Moon. Computer simulations suggest that up to  of the surface may be in permanent shadow. The presence of usable quantities of water on the Moon is an important factor in rendering

text: lunar habitation

text: as a cost-effective plan; the alternative of transporting water from Earth would be prohibitively expensive.

text: A supermoon is the coincidence of a full moon or a new moon with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth.

text: A supermoon is the coincidence of a

text: full moon

text: or a

text: new moon

text: with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth.

text: Lipskiy is a lunar crater on the far side of the Moon. It lies just to the south of the lunar equator, and is the closest named crater to the antipode of the Earth zenith point. That is, it lies in the region of the Moon that is the most distant from the Earth. Lipskiy is located less than one crater diameter to the north of the prominent crater Daedalus. To the northeast is Krasovskiy.

text: Lipskiy is a

text: lunar

text: crater

text: on the

text: far side

text: of the

text: Moon

text: . It lies just to the south of the lunar

text: equator

text: , and is the closest named crater to the

text: antipode

text: of the

text: Earth

text: zenith

text: point. That is, it lies in the region of the Moon that is the most distant from the Earth. Lipskiy is located less than one crater diameter to the north of the prominent crater

text: Daedalus

text: . To the northeast is

text: Krasovskiy

text: An unstable surface could represent another potential problem. It has been shown that the moon is geologically active, with an outer crust with plate tectonics that resembles that on Earth. The reconstruction of the geological activity over a few years of an area the size of the state Alabama showed that a piece of the surface as big as Massachusetts had moved down underneath the crust and disappeared.

text: An unstable surface could represent another potential problem. It has been shown that the moon is geologically active, with an outer crust with

text: plate tectonics

text: that resembles that on Earth. The reconstruction of the geological activity over a few years of an area the size of the state

text: Alabama

text: showed that a piece of the surface as big as

text: Massachusetts

text: had moved down underneath the crust and disappeared.

text: In Norse mythology, Viðfinnr ("wood-Finn") is the father of Hjúki and Bil, a brother and sister who, according to Gylfaginning, were taken up from the earth by Máni, the personified moon, as they were fetching water from the well Byrgir.

text: In

text: Norse mythology

text: , Viðfinnr ("wood-

text: Finn

text: ") is the father of

text: Hjúki and Bil

text: , a brother and sister who, according to

text: Gylfaginning

text: , were taken up from the

text: earth

text: by

text: Máni

text: , the personified moon, as they were fetching water from the well

text: Byrgir

text: The Moon generally has one hemisphere facing the Earth, due to tidal locking. Therefore, humans' first view of the far side of the Moon resulted from lunar exploration on October 7, 1959. However, this simple picture is only approximately true: over time, slightly more than half (about 59%) of the Moon's surface is seen from Earth due to libration.

text: The Moon generally has one

text: hemisphere

text: facing the Earth, due to

text: tidal locking

text: . Therefore, humans' first view of the

text: far side of the Moon

text: resulted from

text: lunar exploration

text: on October 7, 1959. However, this simple picture is only approximately true: over time, slightly more than half (about 59%) of the Moon's surface is seen from Earth due to libration.

text: The theoretical amplitude of oceanic tides caused by the moon is about  at the highest point, which corresponds to the amplitude that would be reached if the ocean possessed a uniform depth, there were no landmasses, and the Earth were rotating in step with the moon's orbit. The sun similarly causes tides, of which the theoretical amplitude is about  (46% of that of the moon) with a cycle time of 12 hours. At spring tide the two effects add to each other to a theoretical level of , while at neap tide the theoretical level is reduced to . Since the orbits of the Earth about the sun, and the moon about the Earth, are elliptical, tidal amplitudes change somewhat as a result of the varying Earth–sun and Earth–moon distances. This causes a variation in the tidal force and theoretical amplitude of about ±18% for the moon and ±5% for the sun. If both the sun and moon were at their closest positions and aligned at new moon, the theoretical amplitude would reach .

text: Roughly speaking, the Moon's prime meridian lies near the center of the Moon's disc as seen from Earth. For precise applications, many coordinate systems have been defined for the Moon, each with a slightly different prime meridian. The IAU recommends the "mean Earth/polar axis" system, in which the prime meridian is the average direction (from the Moon's center) of the Earth's center.

text: Roughly speaking, the Moon's prime meridian lies near the center of the Moon's disc as seen from Earth. For precise applications, many coordinate systems have been defined for the Moon, each with a slightly different prime meridian. The

text: IAU

text: recommends the "mean Earth/polar axis" system, in which the prime meridian is the average direction (from the Moon's center) of the Earth's center.

text: Idolmaster: Xenoglossia centers around mecha and re-imagines the ten prospective idols from The Idolmaster as fighter pilots of those robots, with eight of them also posing as students. The large robots are called Immortal Defender of Legatee (IDOL) and their pilots are called Idolmasters. IDOL pilots have to be girls, and they have to be chosen by the IDOL itself. The Moon was destroyed 107 years prior to the beginning of the story in an event called Lost Artemis. This event caused numerous fragments to fall onto the Earth, which killed about one quarter of the Earth's total population. The remaining fragments of the Moon which orbit around the Earth are called Kompeito or Confeito. Once a fragment falls onto Earth, it is called a Drop. If the Drop is big, resulting in a moderate threat to the Earth, then it will be called Mint Drop or Lemon Drop according to sizes. Humans found a special silicon on Earth, probably from fallen Drops, and started research to turn that silicon into IDOL cores, of which there are five. The IDOLs are named after Lunar maria.

text: Idolmaster: Xenoglossia centers around

text: mecha

text: and re-imagines the ten prospective idols from The Idolmaster as fighter pilots of those robots, with eight of them also posing as students. The large robots are called Immortal Defender of Legatee (IDOL) and their pilots are called Idolmasters. IDOL pilots have to be girls, and they have to be chosen by the IDOL itself. The Moon was destroyed 107 years prior to the beginning of the story in an event called Lost Artemis. This event caused numerous fragments to fall onto the Earth, which killed about one quarter of the Earth's total population. The remaining fragments of the Moon which orbit around the Earth are called

text: Kompeito

text: or Confeito. Once a fragment falls onto Earth, it is called a Drop. If the Drop is big, resulting in a moderate threat to the Earth, then it will be called Mint Drop or Lemon Drop according to sizes. Humans found a special silicon on Earth, probably from fallen Drops, and started research to turn that silicon into IDOL cores, of which there are five. The IDOLs are named after

text: Lunar maria

text: Newton also showed that the same pattern of perturbation applies, not only to the Moon, in its relation to the Earth as disturbed by the Sun, but also to other particles more generally in their relation to the solid Earth as disturbed by the Sun (or by the Moon); for example different portions of the tidal waters at the Earth's surface. The study of the common pattern of these perturbing accelerations grew out of Newton's initial study of the perturbations of the Moon, which he also applied to the forces moving tidal waters. Nowadays this common pattern itself has become often known as a tidal force whether it is being applied to the disturbances of the motions of the Moon, or of the Earth's tidal waters – or of the motions of any other object that suffers perturbations of analogous pattern.

text: Newton also showed that the same pattern of perturbation applies, not only to the Moon, in its relation to the Earth as disturbed by the Sun, but also to other particles more generally in their relation to the solid Earth as disturbed by the Sun (or by the Moon); for example different portions of the tidal waters at the Earth's surface. The study of the common pattern of these perturbing accelerations grew out of Newton's initial study of the perturbations of the Moon, which he also applied to the forces moving tidal waters. Nowadays this common pattern itself has become often known as a

text: tidal force

text: whether it is being applied to the disturbances of the motions of the Moon, or of the Earth's tidal waters – or of the motions of any other object that suffers perturbations of analogous pattern.

text: Quetelet is a lunar crater that lies in the Moon's northern hemisphere, on the far side from the Earth. It lies to the southeast of the crater Schlesinger, and to the east of Von Zeipel. To the east of Quetelet is Perrine.

text: Quetelet is a

text: lunar

text: crater

text: that lies in the

text: Moon

text: 's northern

text: hemisphere

text: , on the

text: far side

text: from the

text: Earth

text: . It lies to the southeast of the crater

text: Schlesinger

text: , and to the east of

text: Von Zeipel

text: . To the east of Quetelet is

text: Perrine

text: Other factors which may affect the properties of lunar soil include large temperature differentials, the presence of a hard vacuum, and the absence of a significant lunar magnetic field (thereby allowing charged solar wind particles to continuously hit the surface of the moon).

text: Other factors which may affect the properties of lunar soil include large

text: temperature

text: differentials

text: , the presence of a hard

text: vacuum

text: , and the absence of a significant lunar

text: magnetic field

text: (thereby allowing charged solar wind particles to continuously hit the surface of the moon).

text: Earth–Moon–Earth communication (EME), also known as moon bounce, is a radio communications technique that relies on the propagation of radio waves from an Earth-based transmitter directed via reflection from the surface of the Moon back to an Earth-based receiver.

text: Earth–Moon–Earth communication (EME), also known as moon bounce, is a

text: radio communications

text: technique that relies on the

text: propagation

text: of

text: radio waves

text: from an

text: Earth

text: -based

text: transmitter

text: directed via

text: reflection

text: from the surface of the

text: Moon

text: back to an Earth-based

text: receiver

text: Since ancient times, the Moon's mean rate of motion relative to the stars had been treated as a constant rate, but in 1695, Edmond Halley had suggested that this mean rate was gradually increasing.  Later, during the eighteenth century, Richard Dunthorne estimated the rate as +10" (arcseconds/century) in terms of the resulting difference in lunar longitude, an effect that became known as the secular acceleration of the Moon. Pierre-Simon Laplace had given an explanation in 1787 in terms of changes in the eccentricity of the Earth's orbit. He considered only the radial gravitational force on the Moon, from the Sun and Earth but obtained close agreement with the historical record of observations.

text: Since ancient times, the

text: Moon

text: 's mean rate of motion relative to the stars had been treated as a constant rate, but in 1695,

text: Edmond Halley

text: had suggested that this mean rate was gradually increasing.  Later, during the eighteenth century,

text: Richard Dunthorne

text: estimated the rate as +10" (arcseconds/century) in terms of the resulting difference in lunar longitude, an effect that became known as the secular acceleration of the Moon.

text: Pierre-Simon Laplace

text: had given an

text: explanation

text: in 1787 in terms of changes in the

text: eccentricity of the Earth's orbit

text: . He considered only the radial gravitational force on the

text: Moon

text: , from the

text: Sun

text: and Earth but obtained close agreement with the historical record of observations.

text: Gravitational Tides are caused by changes in the relative location of the Earth, sun, and moon, whose orbits are perturbed slightly by Jupiter.  Newton's law of universal gravitation states that the gravitational force between a mass at a reference point on the surface of the Earth and another object such as the Moon is inversely proportional to the square of the distance between them.  The declination of the Moon relative to the Earth means that as the Moon orbits the Earth during half the lunar cycle the Moon is closer to the Northern Hemisphere and during the other half the Moon is closer to the Southern Hemisphere.  This periodic shift in distance gives rise to the lunar fortnightly tidal constituent.  The ellipticity of the lunar orbit gives rise to a lunar monthly tidal constituent.  Because of the nonlinear dependence of the force on distance additional tidal constituents exist with frequencies which are the sum and differences of these fundamental frequencies.  Additional fundamental frequencies are introduced by the motion of the Sun and Jupiter, thus tidal constituents exist at all of these frequencies as well as all of the sums and differences of these frequencies, etc.  The mathematical description of the tidal forces is greatly simplified by expressing the forces in terms of gravitational potentials.  Because of the fact that the Earth is approximately a sphere and the orbits are approximately circular it also turns out to be very convenient to describe these gravitational potentials in spherical coordinates using spherical harmonic expansions.

text: Gravitational

text: Tides

text: are caused by changes in the relative location of the Earth, sun, and moon, whose orbits are perturbed slightly by Jupiter.

text: Newton's law of universal gravitation

text: states that the gravitational force between a mass at a reference point on the surface of the Earth and another object such as the Moon is inversely proportional to the square of the distance between them.  The

text: declination

text: Due to the angle at which sunlight strikes this portion of the moon, shadows cast by craters and other geological features are elongated, thereby making such features more apparent to the observer. This phenomenon is similar to the lengthening of shadows on Earth when the sun is low in the sky.  For this reason, much lunar photographic study centers on the illuminated area near the lunar terminator, and the resulting shadows provide accurate descriptions of the terrain.

text: Due to the angle at which

text: sunlight

text: strikes this portion of the moon, shadows cast by

text: crater

text: s and other geological features are elongated, thereby making such features more apparent to the observer. This phenomenon is similar to the lengthening of shadows on Earth when the sun is low in the sky.  For this reason, much lunar photographic study centers on the illuminated area near the lunar terminator, and the resulting shadows provide accurate descriptions of the terrain.

text: Pentland is a lunar impact crater that lies in the southern part of the Moon, and appears foreshortened when viewed from the Earth. About one crater diameter to the southwest is the larger crater Curtius, and to the north-northwest lies Zach.

text: Pentland is a

text: lunar

text: impact crater

text: that lies in the southern part of the

text: Moon

text: , and appears foreshortened when viewed from the

text: Earth

text: . About one crater diameter to the southwest is the larger crater

text: Curtius

text: , and to the north-northwest lies

text: Zach

text: In a like manner, the lunar surface experiences tides of around  amplitude over 27 days, with two components: a fixed one due to Earth, because they are in synchronous rotation, and a varying component from the Sun. The Earth-induced component arises from libration, a result of the Moon's orbital eccentricity (if the Moon's orbit were perfectly circular, there would only be solar tides). Libration also changes the angle from which the Moon is seen, allowing a total of about 59% of its surface to be seen from Earth over time. The cumulative effects of stress built up by these tidal forces produces moonquakes. Moonquakes are much less common and weaker than are earthquakes, although moon quakes can last for up to an hour—a significantly longer time than terrestrial quakes—because of the absence of water to damp out the seismic vibrations. The existence of moonquakes was an unexpected discovery from seismometers placed on the Moon by Apollo astronauts from 1969 through 1972.

text: In a like manner, the lunar surface experiences tides of around  amplitude over 27 days, with two components: a fixed one due to Earth, because they are in

text: synchronous rotation

text: , and a varying component from the Sun. The Earth-induced component arises from

text: libration

text: , a result of the Moon's orbital eccentricity (if the Moon's orbit were perfectly circular, there would only be solar tides). Libration also changes the angle from which the Moon is seen, allowing a total of about 59% of its surface to be seen from Earth over time. The cumulative effects of stress built up by these tidal forces produces

text: moonquakes

text: . Moonquakes are much less common and weaker than are earthquakes, although moon quakes can last for up to an hour—a significantly longer time than terrestrial quakes—because of the absence of water to damp out the seismic vibrations. The existence of moonquakes was an unexpected discovery from

text: seismometer

text: s placed on the Moon by

text: Apollo

text: astronaut

text: s from 1969 through 1972.

text: An experiment was conducted in 1957 at the U.S. Naval Research Laboratory that used the echo from radar signals to determine the Earth-Moon distance. Radar pulses lasting  were broadcast from a  diameter radio dish. After the radio waves echoed off the surface of the Moon, the return signal was detected and the delay time measured. From that measurement, the distance could be calculated.  In practice, however, the signal-to-noise ratio was so low that an accurate measurement could not be reliably produced.

text: An experiment was conducted in 1957 at the U.S. Naval Research Laboratory that used the echo from radar signals to determine the Earth-Moon distance. Radar pulses lasting  were broadcast from a  diameter radio dish. After the radio waves echoed off the surface of the Moon, the return signal was detected and the delay time measured. From that measurement, the distance could be calculated.  In practice, however, the

text: signal-to-noise ratio

text: was so low that an accurate measurement could not be reliably produced.

text: In the alternate universe of Earth X (Earth-9997), the skeletal remains of Devil and Moon-Boy are at the Blue Area of the Moon. In Paradise X, the sequel to Earth X, it is revealed Moon-Boy's people are the ancestors of Wolverine.

text: In the alternate universe of

text: Earth X

text: (Earth-9997), the skeletal remains of Devil and Moon-Boy are at the

text: Blue Area of the Moon

text: . In Paradise X, the sequel to Earth X, it is revealed Moon-Boy's people are the ancestors of

text: Wolverine

text: For other places on the Earth's surface, positions of the Moon can be calculated using the JPL ephemeris calculator.

text: The fact that the Moon is less dense than the Earth is advanced as support for it to be hollow.  The moon's mean density is 3.3 gm/cm3 whereas the Earth's is 5.5. One explanation of this discrepancy is that the moon may have been formed by a giant impact which ejected some of the early Earth's upper crust into its orbit. The Earth's upper mantle and crust are less dense than its core.

text: The fact that the Moon is less dense than the Earth is advanced as support for it to be hollow.  The moon's mean density is 3.3 gm/cm3 whereas the Earth's is 5.5. One explanation of this discrepancy is that

text: the moon may have been formed

text: by a giant impact which ejected some of the early Earth's upper crust into its orbit. The Earth's upper mantle and crust are less dense than its core.

text: Frank, Tank, and Jerry now work to bring the shuttle back to earth, with the plan to achieve a low enough altitude to allow the shuttle to be evacuated over water since landing it would be difficult. Frank successfully pilots the shuttle to reenter orbit but with too fast a speed. After safely ejecting Ethan and Roger, Tank and Jerry stay with Frank regardless of the risk. Frank recalls a maneuver Hawk had used before, purposely stalling the shuttle to drop its speed quickly and allowing him to land the shuttle safely. The crew is welcomed back as heroes. Later, Frank talks with his wife Barbara and contemplates if Hawk made it to the Moon. The film ends with the song Frank Sinatra song "Fly Me to the Moon", zooming in on the surface of the Moon showing that Hawk had indeed arrived, having died while peacefully watching the Earth.

text: Frank, Tank, and Jerry now work to bring the shuttle back to earth, with the plan to achieve a low enough altitude to allow the shuttle to be evacuated over water since landing it would be difficult. Frank successfully pilots the shuttle to reenter orbit but with too fast a speed. After safely ejecting Ethan and Roger, Tank and Jerry stay with Frank regardless of the risk. Frank recalls a maneuver Hawk had used before, purposely

text: stalling

text: the shuttle to drop its speed quickly and allowing him to land the shuttle safely. The crew is welcomed back as heroes. Later, Frank talks with his wife Barbara and contemplates if Hawk made it to the Moon. The film ends with the song

text: Frank Sinatra

text: song "

text: Fly Me to the Moon

text: ", zooming in on the surface of the Moon showing that Hawk had indeed arrived, having died while peacefully watching the Earth.

text: A partial solar eclipse occurred on April 6, 1913. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on April 6, 1913. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The Sun's gravitational effect on the Moon is more than twice that of Earth's on the Moon; consequently, the Moon's trajectory is always convex (as seen when looking Sunward at the entire Sun–Earth–Moon system from a great distance outside Earth–Moon solar orbit), and is nowhere concave (from the same perspective) or looped. That is, the region enclosed by the Moon's orbit of the Sun is a convex set.

text: The Sun's gravitational effect on the Moon is more than twice that of Earth's on the Moon; consequently, the Moon's trajectory is always convex (as seen when looking Sunward at the entire Sun–Earth–Moon system from a great distance outside Earth–Moon solar orbit), and is nowhere concave (from the same perspective) or looped. That is, the region enclosed by the Moon's orbit of the Sun is a

text: convex set

text: The semi-diurnal range (the difference in height between high and low waters over about half a day) varies in a two-week cycle. Approximately twice a month, around new moon and full moon when the Sun, Moon, and Earth form a line (a condition known as syzygy), the tidal force due to the sun reinforces that due to the Moon. The tide's range is then at its maximum; this is called the spring tide. It is not named after the season, but, like that word, derives from the meaning "jump, burst forth, rise", as in a natural spring.

text: The semi-diurnal range (the difference in height between high and low waters over about half a day) varies in a two-week cycle. Approximately twice a month, around

text: new moon

text: and

text: full moon

text: when the Sun, Moon, and Earth form a line (a condition known as

text: syzygy

text: ), the

text: tidal force

text: due to the sun reinforces that due to the Moon. The tide's range is then at its maximum; this is called the spring tide. It is not named after the

text: season

text: , but, like that word, derives from the meaning "jump, burst forth, rise", as in a natural

text: spring

text: Shown here is Newton's diagram from the first (1687) Latin edition of the Principia (Book 3, Proposition 25, at p. 434). Here he introduced his analysis of perturbing accelerations on the Moon in the Sun-Earth-Moon system. Q represents the Sun, S the Earth, and P the Moon.

text: On October 7, 1959, the Soviet probe Luna 3 took the first photographs of the lunar far side, eighteen of them resolvable, covering one-third of the surface invisible from the Earth. The images were analysed, and the first atlas of the far side of the Moon was published by the USSR Academy of Sciences on November 6, 1960. It included a catalog of 500 distinguished features of the landscape. A year later the first globe (1:13 600 000 scale ) containing lunar features invisible from the Earth was released in the USSR, based on images from Luna 3. On July 20, 1965 another Soviet probe, Zond 3, transmitted 25 pictures of very good quality of the lunar far side, with much better resolution than those from Luna 3. In particular, they revealed chains of craters, hundreds of kilometers in length. In 1967 the second part of the "Atlas of the Far Side of the Moon" was published in Moscow, based on data from Zond 3, with the catalog now including 4,000 newly discovered features of the lunar far side landscape. In the same year the first "Complete Map of the Moon" (1:5 000 000 scale) and updated complete globe (1:10 000 000 scale), featuring 95 percent of the lunar surface, were released in the Soviet Union.

text: On October 7, 1959, the

text: Soviet

text: probe

text: Luna 3

text: took the first photographs of the lunar far side, eighteen of them resolvable, covering one-third of the surface invisible from the Earth. The images were analysed, and the first atlas of the far side of the Moon was published by the

text: USSR Academy of Sciences

text: on November 6, 1960. It included a catalog of 500 distinguished features of the landscape. A year later the first globe (1:13 600 000

text: scale

text: ) containing lunar features invisible from the Earth was released in the

text: USSR

text: , based on images from Luna 3. On July 20, 1965 another Soviet probe,

text: Zond 3

text: , transmitted 25 pictures of very good quality of the lunar far side, with much better resolution than those from Luna 3. In particular, they revealed chains of craters, hundreds of kilometers in length. In 1967 the second part of the "Atlas of the Far Side of the Moon" was published in

text: Moscow

text: , based on data from Zond 3, with the catalog now including 4,000 newly discovered features of the lunar far side landscape. In the same year the first "Complete Map of the Moon" (1:5 000 000 scale) and updated complete globe (1:10 000 000 scale), featuring 95 percent of the lunar surface, were released in the Soviet Union.

text: In a turn from the usual engineer-designed lunar habitats, London-based Foster + Partners architectural firm proposed a building construction 3D-printer technology in January 2013 that would use Lunar regolith raw materials to produce Lunar building structures while using enclosed inflatable habitats for housing the human occupants inside the hard-shell Lunar structures. Overall, these habitats would require only ten percent of the structure mass to be transported from Earth, while using local Lunar materials for the other 90 percent of the structure mass."Printed" Lunar soil will provide both "radiation and temperature insulation. Inside, a lightweight pressurized inflatable with the same dome shape will be the living environment for the first human Moon settlers."The building technology will include mixing Lunar material with magnesium oxide, which will turn the "moonstuff into a pulp that can be sprayed to form the block" when a binding salt is applied that "converts [this] material into a stone-like solid."Terrestrial versions of this 3D-printing building technology are already printing  of building material per hour with the next-generation printers capable of  per hour, sufficient to complete a building in a week.

text: In a turn from the usual engineer-designed lunar habitats,

text: London

text: -based

text: Foster + Partners

text: architectural firm proposed a

text: building construction 3D-printer

text: technology in January 2013 that would use Lunar regolith raw materials to produce Lunar building structures while using

text: enclosed inflatable habitats

text: for housing the human occupants inside the hard-shell Lunar structures. Overall, these habitats would require only ten percent of the structure mass to be

text: transported

text: from Earth, while using local Lunar materials for the other 90 percent of the structure mass."Printed" Lunar soil will provide both "

text: radiation

text: and

text: temperature

text: insulation. Inside, a lightweight pressurized inflatable with the same dome shape will be the living environment for the first human Moon settlers."The building technology will include mixing Lunar material with

text: magnesium oxide

text: , which will turn the "moonstuff into a pulp that can be sprayed to form the block" when a binding salt is applied that "converts [this] material into a stone-like solid."Terrestrial versions of this 3D-printing building technology are already printing  of building material per hour with the next-generation printers capable of  per hour, sufficient to complete a building in a week.

text: A partial solar eclipse occurred on March 7, 1989. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on March 7, 1989. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The possibility that water and other volatiles were delivered to the Moon in bolides about 4.0 b.y. accords with available data on volatile contents of igneous rocks [e.g., R. Tartese and M. Anand, Earth Planet. Sci. Letters, v. 361, p. 480-486] but has not been specified in the chemical literature. Earth, Moon, Mars, and Venus thus may all have been recipients of a bombardment of icy bolides, formed originally in the outer half of the asteroid belt, at about this time, which made life on Earth possible. This inference is consistent with current concepts of the formation of asteroids, and of the disruption and loss of most of them, in response to migrations of, particularly, Jupiter, although these concepts carry few constraints on when this occurred.

text: A total solar eclipse will occur on December 26, 2038. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on December 26, 2038. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: The band was protagonist of pictures book, published in November 2009, and called "Il Ritmo Nel Tacco", with Sud Sound System, Raffaele Casarano, Cesare Dell'Anna. The preface author was Caparezza.

text: During dry periods, however, much of the Senne's water was diverted for the needs of the populace of the city as well as to maintain the water level in the Charleroi Canal. This left a flow too feeble to evacuate the filthy water, leaving the sewage, garbage, detritus and industrial waste that had been dumped into the river to accumulate in the stagnant water. The Senne, which a witness in 1853 described as "the most nauseous little river in the world", had become an open-air sewer spreading pestilential odours throughout the city. Early in the second half of the 19th century, Brussels saw numerous dry periods, floods and a cholera epidemic, caused as much by the river itself as by the poverty and the lack of hygiene and potable water in the lower city. This forced the governments of the Province of Brabant and the City of Brussels to act.

text: During dry periods, however, much of the Senne's water was diverted for the needs of the populace of the city as well as to maintain the water level in the Charleroi Canal. This left a flow too feeble to evacuate the filthy water, leaving the

text: sewage

text: , garbage,

text: detritus

text: and industrial waste that had been dumped into the river to accumulate in the stagnant water. The Senne, which a witness in 1853 described as "the most nauseous little river in the world", had become an open-air

text: sewer

text: spreading pestilential odours throughout the city. Early in the second half of the 19th century, Brussels saw numerous dry periods, floods and a

text: cholera

text: epidemic, caused as much by the river itself as by the poverty and the lack of

text: hygiene

text: and

text: potable water

text: in the lower city. This forced the governments of the

text: Province of Brabant

text: and the

text: City of Brussels

text: to act.

text: Racah is a lunar impact crater on the far side of the moon. It lies almost due south of the larger crater Daedalus, and lies across lunar longitude 180°W, i.e. the longitude that is diametrically opposite to the Earth. To the west-southwest of Racah is the crater Aitken, and to the southeast lies De Vries.

text: Racah is a

text: lunar

text: impact crater

text: on the

text: far side

text: of the moon. It lies almost due south of the larger crater

text: Daedalus

text: , and lies across lunar longitude 180°W, i.e. the longitude that is diametrically opposite to the Earth. To the west-southwest of Racah is the crater

text: Aitken

text: , and to the southeast lies

text: De Vries

text: Lyapunov is a lunar crater named for Aleksandr Lyapunov that is located along the east-northeastern limb of the Moon, and is viewed from the side by observers on Earth. The eastern rim of this crater just falls into the section of the Moon called the far side, and visibility of this formation is affected by libration.

text: Lyapunov is a

text: lunar

text: crater

text: named for

text: Aleksandr Lyapunov

text: that is located along the east-northeastern limb of the

text: Moon

text: , and is viewed from the side by observers on

text: Earth

text: . The eastern rim of this crater just falls into the section of the Moon called the

text: far side

text: , and visibility of this formation is affected by

text: libration

text: The gas giant planet "b" is located in the liquid water habitable zone of Mu Arae. This would prevent an Earth-like planet from forming in the habitable zone, however large moons of the gas giant could potentially support liquid water. On the other hand, it is unclear whether such massive moons could actually form around a gas giant planet, thanks to an apparent scaling law between the mass of the planet and its satellite system. In addition, measurements of the star's ultraviolet flux suggest that any potentially habitable planets or moons may not receive enough ultraviolet to trigger the formation of biomolecules.  Planet "d" would receive a similar amount of ultraviolet to the Earth and thus lies in the ultraviolet habitable zone, however, it would be too hot for any moons to support surface liquid water.

text: The gas giant planet "b" is located in the liquid water habitable zone of Mu Arae. This would prevent an Earth-like planet from forming in the habitable zone, however large

text: moons

text: of the gas giant could potentially support liquid water. On the other hand, it is unclear whether such massive moons could actually form around a gas giant planet, thanks to an apparent scaling law between the mass of the planet and its satellite system. In addition, measurements of the star's

text: ultraviolet

text: flux

text: suggest that any potentially

text: habitable

text: planets or moons may not receive enough ultraviolet to trigger the formation of

text: biomolecule

text: s.  Planet "d" would receive a similar amount of ultraviolet to the Earth and thus lies in the

text: ultraviolet habitable zone

text: , however, it would be too hot for any moons to support surface liquid water.

text: An orrery should properly include the Sun, the Earth and the Moon (plus optionally other planets). A model that only includes the Earth, the Moon and the Sun is called a tellurion or tellurium, and one which only includes the Earth and the Moon is a lunarium. A jovilabe is a model of Jupiter and its moons.

text: An orrery should properly include the Sun, the Earth and the Moon (plus optionally other planets). A model that only includes the Earth, the Moon and the Sun is called a

text: tellurion

text: or tellurium, and one which only includes the Earth and the Moon is a

text: lunarium

text: . A

text: jovilabe

text: is a model of

text: Jupiter

text: and its moons.

text: American aerospace engineer and political scientist Thomas Gangale first published regarding the Darian calendar in 1986, with additional details published in 1998 and 2006. It has 24 months to accommodate the longer Martian year while keeping the notion of a "month" that is reasonably similar to the length of an Earth month. On Mars, a "month" would have no relation to the orbital period of any moon of Mars, since Phobos and Deimos orbit in about 7 hours and 30 hours respectively. However, Earth and Moon would generally be visible to the naked eye when they were above the horizon at night, and the time it takes for the Moon to move from maximum separation in one direction to the other and back as seen from Mars is close to a Lunar month.

text: American aerospace engineer and political scientist Thomas Gangale first published regarding the

text: Darian calendar

text: in 1986, with additional details published in 1998 and 2006. It has 24 months to accommodate the longer Martian year while keeping the notion of a "month" that is reasonably similar to the length of an Earth month. On Mars, a "month" would have no relation to the orbital period of any moon of Mars, since

text: Phobos

text: and

text: Deimos

text: orbit in about 7 hours and 30 hours respectively. However, Earth and Moon would generally be visible to the naked eye when they were above the horizon at night, and the time it takes for the Moon to move from maximum separation in one direction to the other and back as seen from Mars is close to a

text: Lunar month

text: Luna 17 continued the spate of successes in Soviet lunar exploration begun by Luna 16 and Zond 8. Luna 17 carried Lunokhod 1, the first in a series of robot lunar roving vehicles whose conception had begun in the early 1960s, originally as part of the piloted lunar landing operations. This was the second attempt to land such a vehicle on the Moon after a failure in February 1969. The descent stage was equipped with two landing ramps for the "ascent stage," that is, the rover, to disembark onto the Moon’s surface. The 756-kilogram rover stood about 1.35 meters high and was 2.15 meters across. Each of its eight wheels could be controlled independently for two forward and two reverse speeds. Its top speed was about 100 meters per hour, with commands issued by a five-man team of "drivers" on Earth who had to deal with the 5-second delay. The set of scientific instruments was powered by solar cells (installed on the inside of the hinged top lid of the rover) and chemical batteries. After two mid-course corrections en route to the Moon, Luna 17 entered lunar orbit and then landed on the lunar surface at 03:46:50 UT on 17 November 1970 at 38°17' north latitude and 35° west longitude, about 2,500 kilometers from the Luna 16 site in the Sea of Rains. The Lunokhod 1 rover rolled over the ramps and onto the lunar surface at 06:28 UT. During its 322 Earth days of operation, the rover traveled 10.54 kilometers and returned more than 20,000 TV images and 206 high-resolution panoramas. In addition, Lunokhod 1 performed twenty-five soil analyses with its RIFMA X-ray fluorescence spectrometer and used its penetrometer at 500 different locations. Controllers finished the last communications session with Lunokhod 1 at 13:05 UT on 14 September 1971. Attempts to reestablish contact were finally discontinued on 4 October.

text: Luna 17 continued the spate of successes in Soviet lunar exploration begun by

text: Luna 16

text: and

text: Zond 8

text: . Luna 17 carried Lunokhod 1, the first in a series of robot lunar roving vehicles whose conception had begun in the early 1960s, originally as part of the piloted lunar landing operations. This was the second attempt to land such a vehicle on the Moon after a failure in February 1969. The descent stage was equipped with two landing ramps for the "ascent stage," that is, the rover, to disembark onto the Moon’s surface. The 756-kilogram rover stood about 1.35 meters high and was 2.15 meters across. Each of its eight wheels could be controlled independently for two forward and two reverse speeds. Its top speed was about 100 meters per hour, with commands issued by a five-man team of "drivers" on Earth who had to deal with the 5-second delay. The set of scientific instruments was powered by solar cells (installed on the inside of the hinged top lid of the rover) and chemical batteries. After two mid-course corrections en route to the Moon, Luna 17 entered lunar orbit and then landed on the lunar surface at 03:46:50 UT on 17 November 1970 at 38°17' north latitude and 35° west longitude, about 2,500 kilometers from the

text: Luna 16

text: site in the

text: Sea of Rains

text: . The Lunokhod 1 rover rolled over the ramps and onto the lunar surface at 06:28 UT. During its 322 Earth days of operation, the rover traveled 10.54 kilometers and returned more than 20,000 TV images and 206 high-resolution panoramas. In addition, Lunokhod 1 performed twenty-five soil analyses with its RIFMA X-ray fluorescence spectrometer and used its penetrometer at 500 different locations. Controllers finished the last communications session with Lunokhod 1 at 13:05 UT on 14 September 1971. Attempts to reestablish contact were finally discontinued on 4 October.

text: Lunar eclipses occur when the Moon passes through the Earth's shadow. This happens only during a full moon, when the Moon is on the far side of the Earth from the Sun. Unlike a solar eclipse, an eclipse of the Moon can be observed from nearly an entire hemisphere. For this reason it is much more common to observe a lunar eclipse from a given location. A lunar eclipse lasts longer, taking several hours to complete, with totality itself usually averaging anywhere from about 30 minutes to over an hour.

text: Lunar eclipses occur when the Moon passes through the Earth's shadow. This happens only during a

text: full moon

text: , when the Moon is on the far side of the Earth from the Sun. Unlike a solar eclipse, an eclipse of the Moon can be observed from nearly an entire hemisphere. For this reason it is much more common to observe a lunar eclipse from a given location. A lunar eclipse lasts longer, taking several hours to complete, with totality itself usually averaging anywhere from about 30 minutes to over an hour.

text: White toured with Waters in The Dark Side of the Moon Live tour from June 2006, having played in Europe, North America, Australia, Asia and South America. He also performed with Waters at Live Earth.

text: White toured with Waters in

text: The Dark Side of the Moon Live

text: tour from June 2006, having played in Europe, North America, Australia, Asia and South America. He also performed with Waters at

text: Live Earth

text: The first memory is one from the clone Emily's childhood, involving a controversial exhibit in a museum where a male clone without a brain, nicknamed affectionately by the public as David, was kept in stasis; she recalls her frequent visits to David over the years and expresses her sadness when he finally died at the age of 72. The second memory is of the clone Emily's first job, supervising solar-powered and sentient worker robots on the surface of the Earth's moon. She had programmed the robots to fear death and darkness, and they, as a result, are compelled to be in constant motion, always walking where the light of the sun hits the lunar surface. Too expensive to remove, the robots remain on the moon in endless movement, occasionally sending depressed poetry. Due to a recession in the lunar economy, Emily Clone was sent home after six lunar cycles and separated from an inanimate rock that she had grown to love.

text: The first memory is one from the clone Emily's childhood, involving a controversial exhibit in a museum where a male clone without a brain, nicknamed affectionately by the public as David, was kept in

text: stasis

text: ; she recalls her frequent visits to David over the years and expresses her sadness when he finally died at the age of 72. The second memory is of the clone Emily's first job, supervising

text: solar-powered

text: and sentient worker robots on the surface of the Earth's moon. She had programmed the robots to fear death and darkness, and they, as a result, are compelled to be in constant motion, always walking where the light of the sun hits the lunar surface. Too expensive to remove, the robots remain on the moon in endless movement, occasionally sending depressed poetry. Due to a recession in the lunar economy, Emily Clone was sent home after six lunar cycles and separated from an inanimate rock that she had grown to love.

text: Most places experience two high tides each day, occurring at intervals of about 12 hours and 25 minutes, half the period that it takes for the Earth to make a complete revolution and return the Moon to its previous position relative to an observer. The Moon's mass is some 27 million times smaller than the Sun, but it is 400 times closer to the Earth. Tidal force or tide-raising force decreases rapidly with distance, so the moon has more than twice as great an effect on tides as the Sun. A bulge is formed in the ocean at the place where the Earth is closest to the Moon, because it is also where the effect of the Moon's gravity is stronger. On the opposite side of the Earth, the lunar force is at its weakest and this causes another bulge to form. These bulges rotate around the Earth as the moon does. The Sun's effect is less powerful but, when the Sun, Moon and Earth are all aligned at the full and new moons, the combined effect results in the high "spring tides". In contrast, when the Sun is at 90° from the Moon as viewed from Earth, the combined gravitational effect on tides is correspondingly reduced, causing the lower "neap tides".

text: Most places experience two high tides each day, occurring at intervals of about 12 hours and 25 minutes, half the period that it takes for the Earth to make a complete revolution and return the Moon to its previous position relative to an observer. The Moon's mass is some 27 million times smaller than the Sun, but it is 400 times closer to the Earth.

text: Tidal force

text: or tide-raising force decreases rapidly with distance, so the moon has more than twice as great an effect on tides as the Sun. A bulge is formed in the ocean at the place where the Earth is closest to the Moon, because it is also where the effect of the Moon's gravity is stronger. On the opposite side of the Earth, the lunar force is at its weakest and this causes another bulge to form. These bulges rotate around the Earth as the moon does. The Sun's effect is less powerful but, when the Sun, Moon and Earth are all aligned at the

text: full

text: and

text: new moon

text: s, the combined effect results in the high "spring tides". In contrast, when the Sun is at 90° from the Moon as viewed from Earth, the combined gravitational effect on tides is correspondingly reduced, causing the lower "neap tides".

text: If it were to remain on the same trajectory as the spacecraft, the S-IVB could have presented a collision hazard so its remaining propellants were vented and the auxiliary propulsion system fired to move it away. For lunar missions before Apollo 13, the S-IVB was directed toward the Moon's trailing edge in its orbit so that the moon would slingshot it beyond earth escape velocity and into solar orbit. From Apollo 13 onwards, controllers directed the S-IVB to hit the Moon. Seismometers left behind by previous missions detected the impacts, and the information helped map the interior structure of the Moon.

text: If it were to remain on the same trajectory as the spacecraft, the S-IVB could have presented a collision hazard so its remaining propellants were vented and the auxiliary propulsion system fired to move it away. For lunar missions before

text: Apollo 13

text: , the S-IVB was directed toward the Moon's trailing edge in its orbit so that the moon would

text: slingshot

text: it beyond earth escape velocity and into solar orbit. From Apollo 13 onwards, controllers directed the S-IVB to hit the Moon.

text: Seismometer

text: s left behind by previous missions detected the impacts, and the information helped map the interior structure of the Moon.

text: Sverdrup is a lunar crater that is located about one crater diameter from the southern pole of the Moon. It lies on the far side of the Moon with respect to the Earth, in an area of the surface that is only illuminated by very oblique light from the Sun. The interior part of the crater is cloaked in perpetual darkness, and thus has not been mapped using photography. Portions of the rim are illuminated, however, and give the appearance of a worn formation that has been intruded upon by adjacent formations.

text: Sverdrup is a

text: lunar

text: crater

text: that is located about one crater diameter from the

text: southern pole

text: of the

text: Moon

text: . It lies on the

text: far side

text: of the Moon with respect to the

text: Earth

text: , in an area of the surface that is only illuminated by very oblique light from the

text: Sun

text: . The interior part of the crater is cloaked in perpetual darkness, and thus has not been mapped using photography. Portions of the rim are illuminated, however, and give the appearance of a worn formation that has been intruded upon by adjacent formations.

text: Helmert is a lunar crater at the southern edge of the Mare Smythii. It lies near the eastern limb of the Moon, and from the Earth it is seen nearly from the side. The visibility of this feature can be strongly affected by libration of the Moon in its orbit.

text: Helmert is a

text: lunar

text: crater

text: at the southern edge of the

text: Mare Smythii

text: . It lies near the eastern limb of the

text: Moon

text: , and from the

text: Earth

text: it is seen nearly from the side. The visibility of this feature can be strongly affected by

text: libration

text: of the Moon in its orbit.

text: The intensity of visible sunlight striking the surface of the Moon is essentially the same as at the surface of the Earth. The albedo of the Moon's surface material is lower (darker) than that of the earth's surface, and the Looney 11 rule increases exposure by one stop versus the Sunny 16 rule.  Many photographers simply use the f/16-based Sunny 16 rule, unmodified, for lunar photographs.

text: The intensity of visible sunlight striking the surface of the Moon is essentially the same as at the surface of the Earth. The

text: albedo

text: of the Moon's surface material is lower (darker) than that of the earth's surface, and the Looney 11 rule increases exposure by one stop versus the Sunny 16 rule.  Many photographers simply use the f/16-based

text: Sunny 16 rule

text: , unmodified, for lunar photographs.

text: The Moon's maximum and minimum declination also vary because the plane of the Moon's orbit around the Earth is inclined by about 5.14° to the ecliptic (the plane of the Earth's orbit around the Sun), and the direction of lunar orbit inclination gradually changes over an 18.6-year cycle, alternately adding to or subtracting from the 23.5° tilt of the Earth's axis. As a consequence, the maximum declination of the Moon varies from roughly (23.5° − 5°) = 18.5° to (23.5° + 5°) = 28.5°. As a result, at minor lunar standstill, the Moon will change its declination during the nodal period from +18.5° to −18.5°, which is a total movement of 37°. Then, 9.3 years later, during the major lunar standstill, the Moon will change its declination during the nodal period from +28.5° to −28.5°, which is a total movement of 57°, which is enough to take its culmination from high in the sky to low on the horizon in just two weeks (half an orbit).

text: The Moon's maximum and minimum declination also vary because the plane of the Moon's orbit around the Earth is inclined by about 5.14° to the ecliptic (the plane of the Earth's orbit around the Sun), and the direction of lunar orbit inclination gradually changes over an 18.6-year cycle, alternately adding to or subtracting from the 23.5° tilt of the Earth's axis. As a consequence, the maximum declination of the Moon varies from roughly (23.5° − 5°) = 18.5° to (23.5° + 5°) = 28.5°. As a result, at minor lunar standstill, the Moon will change its declination during the nodal period from +18.5° to −18.5°, which is a total movement of 37°. Then, 9.3 years later, during the major lunar standstill, the Moon will change its declination during the nodal period from +28.5° to −28.5°, which is a total movement of 57°, which is enough to take its

text: culmination

text: from high in the sky to low on the horizon in just two weeks (half an orbit).

text: Despite the Moon's rotational and orbital periods being exactly locked, about 59% of the Moon's total surface may be seen with repeated observations from Earth due to the phenomena of libration and parallax. Librations are primarily caused by the Moon's varying orbital speed due to the eccentricity of its orbit: this allows up to about 6° more along its perimeter to be seen from Earth. Parallax is a geometric effect: at the surface of Earth we are offset from the line through the centers of Earth and Moon, and because of this we can observe a bit (about 1°) more around the side of the Moon when it is on our local horizon.

text: Despite the Moon's rotational and orbital periods being exactly locked, about 59% of the Moon's total surface may be seen with repeated observations from Earth due to the phenomena of

text: libration

text: and

text: parallax

text: . Librations are primarily caused by the Moon's varying orbital speed due to the

text: eccentricity

text: of its orbit: this allows up to about 6° more along its perimeter to be seen from Earth. Parallax is a geometric effect: at the surface of Earth we are offset from the line through the centers of Earth and Moon, and because of this we can observe a bit (about 1°) more around the side of the Moon when it is on our local horizon.

text: Gum is a lunar crater that is located near the southeastern limb of the Moon, and is viewed nearly from the side from Earth. It lies along the western edge of the irregular Mare Australe, to the northeast of the crater Hamilton. To the north-northwest is the larger Abel, and to the east-southeast on the far side of the Moon is Jenner.

text: Gum is a

text: lunar

text: crater

text: Moon

text: , and is viewed nearly from the side from

text: Earth

text: . It lies along the western edge of the irregular

text: Mare Australe

text: , to the northeast of the crater

text: Hamilton

text: . To the north-northwest is the larger

text: Abel

text: , and to the east-southeast on the

text: far side

text: of the Moon is

text: Jenner

text: Peek is a small lunar impact crater that is located in the northern part of the Mare Smythii near the eastern limb of the Moon. This part of the lunar surface is subject to the effects of libration, and the crater can be hidden from sight during an unfavorable libration. Even when visible, however, the crater is seen almost edge-on, making it difficult to see much detail from the Earth. Due to foreshortening the crater appears close to Schubert, even though the two are about 60 km apart. It lies to the south-southeast of the large crater Neper.

text: Peek is a small

text: lunar

text: impact crater

text: that is located in the northern part of the

text: Mare Smythii

text: near the eastern limb of the

text: Moon

text: . This part of the lunar surface is subject to the effects of

text: libration

text: , and the crater can be hidden from sight during an unfavorable libration. Even when visible, however, the crater is seen almost edge-on, making it difficult to see much detail from the

text: Earth

text: . Due to foreshortening the crater appears close to

text: Schubert

text: , even though the two are about 60 km apart. It lies to the south-southeast of the large crater

text: Neper

text: The Han-era Chinese discussed the illumination and shapes of heavenly bodies: were they flat and circular, or were they rounded and spherical? Jing Fang wrote in the 1st century BCE that Han astronomers believed the Sun, Moon, and planets were spherical like balls or crossbow bullets. He also wrote that the Moon and planets produce no light of their own, are viewable to people on Earth only because they are illuminated by the Sun, and those parts not illuminated by the Sun would be dark on the other side. For this, Jing compared the Moon to a mirror illuminating light. In the 2nd century CE, Zhang Heng drew a similar comparison to Jing's by stating that the Sun is like fire and the Moon and planets are like water, since fire produces light and water reflects it. He also repeated Jing's comment that the side of the moon not illuminated by the Sun was left in darkness. However, Zhang noted that sunlight did not always reach the Moon since the Earth obstructs the rays during a lunar eclipse. He also noted that a solar eclipse occurred when the Moon and Sun crossed paths to block sunlight from reaching earth.

text: The Han-era Chinese discussed the illumination and shapes of heavenly bodies: were they flat and circular, or were they rounded and spherical? Jing Fang wrote in the 1st century BCE that Han astronomers believed the Sun, Moon, and planets were spherical like balls or

text: crossbow

text: bullets. He also wrote that the Moon and planets produce no light of their own, are viewable to people on Earth only because they are illuminated by the Sun, and those parts not illuminated by the Sun would be dark on the other side. For this, Jing compared the Moon to a mirror illuminating light. In the 2nd century CE, Zhang Heng drew a similar comparison to Jing's by stating that the Sun is like fire and the Moon and planets are like water, since fire produces light and water reflects it. He also repeated Jing's comment that the side of the moon not illuminated by the Sun was left in darkness. However, Zhang noted that

text: sunlight

text: did not always reach the Moon since the Earth obstructs the rays during a

text: lunar eclipse

text: . He also noted that a

text: solar eclipse

text: occurred when the Moon and Sun crossed paths to block sunlight from reaching earth.

text: As part of human exploration of the Moon, numerous space missions have been undertaken to study Earth's natural satellite. Of the Moon landings; Luna 2 was the first spacecraft to reach its surface successfully, intentionally impacting the Moon on 13 September 1959. In 1966, Luna 9 became the first spacecraft to achieve a controlled soft landing, while Luna 10 became the first mission to enter orbit.

text: As part of human

text: exploration of the Moon

text: , numerous space missions have been undertaken to study Earth's natural satellite. Of the

text: Moon landing

text: s;

text: Luna 2

text: was the first spacecraft to reach its surface successfully, intentionally impacting the Moon on 13 September 1959. In 1966,

text: Luna 9

text: became the first spacecraft to achieve a controlled

text: soft landing

text: , while

text: Luna 10

text: became the first mission to enter orbit.

text: The Moon has an outer shell of low-density crystalline rock that is a few hundred kilometers thick, which formed due to a rapid creation. The craters of the moon have been well preserved through time and were once thought to have been the result of extreme volcanic activity, but actually were formed by meteorites, nearly all of which took place in the first few hundred million years after the Moon formed. Around 500 million years afterward, the Moon's mantle was able to be extensively melted due to the decay of radioactive elements. Massive basaltic eruptions took place generally at the base of large impact craters. Also, eruptions may have taken place due to a magma reservoir at the base of the crust. This forms a dome, possibly the same morphology of a shield volcano where calderas universally are known to form. Although caldera-like structures are rare on the Moon, they are not completely absent. The Compton-Belkovich Volcanic Complex on the far side of the Moon is thought to be a caldera, possibly an ash-flow caldera.

text: The

text: Moon

text: has an outer shell of low-density crystalline rock that is a few hundred kilometers thick, which formed due to a rapid creation. The craters of the moon have been well preserved through time and were once thought to have been the result of extreme volcanic activity, but actually were formed by meteorites, nearly all of which took place in the first few hundred million years after the Moon formed. Around 500 million years afterward, the Moon's mantle was able to be extensively melted due to the decay of radioactive elements. Massive basaltic eruptions took place generally at the base of large impact craters. Also, eruptions may have taken place due to a magma reservoir at the base of the crust. This forms a dome, possibly the same morphology of a shield volcano where calderas universally are known to form. Although caldera-like structures are rare on the Moon, they are not completely absent. The

text: Compton-Belkovich Volcanic Complex

text: on the

text: far side of the Moon

text: is thought to be a caldera, possibly an

text: ash-flow

text: caldera.

text: However, the delta-v to reach near-Earth objects is usually over 3.8 km/s, which is still less than the delta-v to reach the Moon's surface. In general bodies that are much further away or closer to the sun than Earth have more frequent windows for travel, but usually require larger delta-vs.

text: The surface of the Moon has been subject to billions of years of collisions with both small and large asteroidal and cometary materials. Over time, these impact processes have pulverized and "gardened" the surface materials, forming a fine grained layer termed "regolith". The thickness of the regolith varies between 2 meters beneath the younger maria, to up to 20 meters beneath the oldest surfaces of the lunar highlands. The regolith is predominantly composed of materials found in the region, but also contains traces of materials ejected by distant impact craters. The term "mega-regolith" is often used to describe the heavily fractured bedrock directly beneath the near-surface regolith layer.

text: A partial solar eclipse occurred on December 2, 1956. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 2, 1956. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: In his exploration of the Heavens, Lewis works to explain much of the basics of medieval cosmology. He begins by explaining the phenomenon of "kindly enclyning": everything returns to the place from which it is drawn. In the medieval conception, everything was made up of the Four Contraries: hot, cold, moist, and dry. These combine to give us the Four Elements: "The union of hot and dry becomes fire; that of hot and moist, air; of cold and moist, water; of cold and dry, earth." There is also a fifth element, aether, that humans do not experience. In the sublunary world, all the elements have sorted themselves out: "Earth, the heaviest, has gathered itself together at the centre. On it lies the lighter water; above that, the still lighter air. Fire, the lightest of all, whenever it was free, has flown up to the circumference of Nature and forms a sphere just below the orbit of the Moon."

text: In his exploration of the Heavens, Lewis works to explain much of the basics of medieval

text: cosmology

text: . He begins by explaining the phenomenon of "kindly enclyning": everything returns to the place from which it is drawn. In the medieval conception, everything was made up of the Four Contraries: hot, cold, moist, and dry. These combine to give us the Four Elements: "The union of hot and dry becomes fire; that of hot and moist, air; of cold and moist, water; of cold and dry, earth." There is also a fifth element,

text: aether

text: , that humans do not experience. In the sublunary world, all the elements have sorted themselves out: "Earth, the heaviest, has gathered itself together at the centre. On it lies the lighter water; above that, the still lighter air. Fire, the lightest of all, whenever it was free, has flown up to the circumference of Nature and forms a sphere just below the orbit of the Moon."

text: Abhimanyu was the reincarnation of the Varchas, son of the moon-god (Chandra). When the moon-god was asked to let his son incarnate himself on earth, he made a pact that his son will only remain on earth for 16 years as he could not bear to be separated from him.

text: Abhimanyu was the reincarnation of the Varchas, son of the moon-god (

text: Chandra

text: ). When the moon-god was asked to let his son incarnate himself on earth, he made a pact that his son will only remain on earth for 16 years as he could not bear to be separated from him.

text: The Luna 21 spacecraft landed on the Moon and deployed the second Soviet lunar rover (Lunokhod 2) in January 1973.   The primary objectives of the mission were to collect images of the lunar surface, examine ambient light levels to determine the feasibility of astronomical observations from the Moon, perform laser ranging experiments from Earth, observe solar X-rays, measure local magnetic fields, and study the soil mechanics of the lunar surface material.

text: The

text: Luna 21

text: spacecraft landed on the Moon and deployed the second Soviet

text: lunar rover

text: (Lunokhod 2) in January 1973.   The primary objectives of the mission were to collect images of the lunar surface, examine

text: ambient light

text: levels to determine the feasibility of astronomical observations from the Moon, perform

text: laser ranging

text: experiments from

text: Earth

text: , observe solar

text: X-ray

text: s, measure local

text: magnetic field

text: s, and study the

text: soil mechanics

text: of the

text: lunar surface material

text: The concept of the habitable zone (or Liquid Water Zone) defining a region where water can exist on the surface, is based on the properties of both the Earth and Sun. Under this model, Earth orbits roughly at the centre of this zone or in the "Goldilocks" position. Earth is the only planet in the universe confirmed to possess large bodies of surface water. Venus is on the hot side of the zone while Mars is on the cold side. Neither are known to have persistent surface water, though evidence exists that Mars did have in its ancient past, and it is speculated that the same was the case for Venus.<ref name='Venus Hashimoto'/> Thus extrasolar planets (or moons) in the Goldilocks position with substantial atmospheres may possess oceans and water clouds like those on Earth. In addition to surface water, a true Earth analog would require a mix of oceans or lakes and areas not covered by water, or land.

text: A partial solar eclipse occurred on May 11, 1975. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on May 11, 1975. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The Moon orbits Earth in the prograde direction and completes one revolution relative to the stars in approximately 27.322 days (a sidereal month). Earth and the Moon orbit about their barycentre (common center of mass), which lies about  from Earth's center (about  of the radius of Earth). On average, the Moon is at a distance of about  from Earth's centre, which corresponds to about 60 Earth radii. With a mean orbital velocity of , the Moon appears to move relative to the stars each hour by an amount roughly equal to its angular diameter, or by about half a degree. The Moon differs from most satellites of other planets in that its orbit is close to the plane of the ecliptic, and not to Earth's equatorial plane. The plane of the lunar orbit is inclined to the ecliptic by about 5°, whereas the Moon's equatorial plane is inclined by only 1.5° to the ecliptic.

text: The

text: Moon

text: orbit

text: s

text: Earth

text: in the

text: prograde

text: direction and completes one revolution relative to the stars in approximately 27.322 days (a

text: sidereal month

text: ). Earth and the Moon orbit about their

text: barycentre

text: (common center of mass), which lies about  from Earth's center (about  of the radius of Earth). On average, the Moon is at a distance of about  from Earth's centre, which corresponds to about 60 Earth radii. With a mean orbital velocity of , the Moon appears to move relative to the

text: star

text: s each hour by an amount roughly equal to its

text: angular diameter

text: , or by about half a degree. The Moon differs from most

text: satellites

text: of other

text: planet

text: s in that its orbit is close to the plane of the

text: ecliptic

text: , and not to Earth's

text: equatorial plane

text: . The plane of the lunar orbit is inclined to the ecliptic by about 5°, whereas the Moon's equatorial plane is inclined by only 1.5° to the ecliptic.

text: Poczobutt is a large lunar impact crater that is located on the far side of the Moon, just beyond the northwestern limb in an area occasionally brought into sight due to libration effects. This is a damaged formation that is partly overlain by several named craters. Across the rim to the north-northeast is the crater Smoluchowski. The crater Zsigmondy overlies the northeastern rim, and Omar Khayyam is located in the western part of Poczobutt's interior.

text: Poczobutt is a large

text: lunar

text: impact crater

text: that is located on the

text: far side

text: of the

text: Moon

text: , just beyond the northwestern limb in an area occasionally brought into sight due to

text: libration

text: effects. This is a damaged formation that is partly overlain by several named craters. Across the rim to the north-northeast is the crater

text: Smoluchowski

text: . The crater

text: Zsigmondy

text: overlies the northeastern rim, and

text: Omar Khayyam

text: is located in the western part of Poczobutt's interior.

text: Over the course of time, many of the satellite craters were assigned an eponym by lunar observers. The process of naming lunar features was assumed by the International Astronomical Union (IAU) in 1919. The commission for naming these features formally adopted the convention of using capital Roman letters to identify craters and valleys.

text: Over the course of time, many of the satellite craters were assigned an

text: eponym

text: by lunar observers. The process of naming lunar features was assumed by the

text: International Astronomical Union

text: (IAU) in 1919. The commission for naming these features formally adopted the convention of using capital Roman letters to identify craters and valleys.

text: Lunar Corporation: The Lunar Corporation (LC) is a matriarchy faction of space colonists who colonized the Moon and cut themselves off from Earth soon after the 3rd World War. Normally a pacifist faction, the matriarchal LC are forced to head to Earth in order to secure minerals to build their Evacuation Ship (due to the Moon's general lack of accessible resources, in real life as well as in the game).  The Lunar Corporation is by far the most advanced of the three factions, utilizing solar power as well as antigravity vehicles (explained, in the game, as a result of researching extraterrestrial technologies). Because of this, they do not build trenches or dig underground tunnels like the UCS and ED. Also, instead of constructing buildings like the other two factions, the Lunar Corporation is able to transport them from orbit to the battlefield. In combat, they use exotic weapons such as electro-cannons and sonic weapons (originally a mining equipment). LC units generally have slightly less armor and firepower than that of the other two factions, but are equipped with anti-energy weapon shields that have twice the strength of the other sides. In the single-player campaign, the forces of the LC are further bolstered by the solitary alien craft known as the Fang, a gift from the UCS in exchange for an alliance. Although losing this one-of-a-kind unit means instant failure, the Fang's weapon is capable of easily decimating any opponent it comes across—that is, until its ammo runs out.

text: Lunar Corporation: The Lunar Corporation (LC) is a

text: matriarchy

text: faction of space colonists who colonized the Moon and cut themselves off from Earth soon after the 3rd World War. Normally a

text: pacifist

text: faction, the matriarchal LC are forced to head to Earth in order to secure minerals to build their Evacuation Ship (due to the Moon's general lack of accessible resources, in real life as well as in the game).  The Lunar Corporation is by far the most advanced of the three factions, utilizing

text: solar power

text: as well as

text: antigravity

text: vehicles (explained, in the game, as a result of researching

text: extraterrestrial

text: technologies). Because of this, they do not build trenches or dig underground tunnels like the UCS and ED. Also, instead of constructing buildings like the other two factions, the Lunar Corporation is able to transport them from orbit to the battlefield. In combat, they use exotic weapons such as electro-cannons and sonic weapons (originally a mining equipment). LC units generally have slightly less armor and firepower than that of the other two factions, but are equipped with anti-energy weapon shields that have twice the strength of the other sides. In the single-player campaign, the forces of the LC are further bolstered by the solitary alien craft known as the Fang, a gift from the UCS in exchange for an alliance. Although losing this one-of-a-kind unit means instant failure, the Fang's weapon is capable of easily decimating any opponent it comes across—that is, until its ammo runs out.

text: A partial solar eclipse occurred on April 17, 1996. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on April 17, 1996. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: From Romulus' surface, Sylvia takes up an angular region 16°×10° across, while Remus's apparent size varies between 0.62° and 0.19° (for comparison, Earth's Moon has an apparent size of about 0.5°).

text: From Romulus' surface, Sylvia takes up an angular region 16°×10° across, while Remus's apparent size varies between 0.62° and 0.19° (for comparison, Earth's

text: Moon

text: has an apparent size of about 0.5°).

text: A partial solar eclipse occurred on January 5, 1935. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.It was the last eclipse of solar saros 111 with the moon's penumbra touching the earth for just 10 minutes.

text: A partial

text: solar eclipse

text: occurred on January 5, 1935. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.It was the last eclipse of

text: solar saros 111

text: with the moon's penumbra touching the earth for just 10 minutes.

text: The phase diagram explains why liquids do not exist in space or any other vacuum. Since the pressure is zero (except on surfaces or interiors of planets and moons) water and other liquids exposed to space will either immediately boil or freeze depending on the temperature. In regions of space near the earth, water will freeze if the sun is not shining directly on it and vapourize (sublime) as soon as it is in sunlight. If water exists as ice on the moon, it can only exist in shadowed holes where the sun never shines and where the surrounding rock doesn't heat it up too much. At some point near the orbit of Saturn, the light from the sun is too faint to sublime ice to water vapour. This is evident from the longevity of the ice that composes Saturn's rings.

text: As of their December 2004 midterm architecture briefing to NASA, their proposed transportation architecture included three types of elements: Spiral 1 (Earth-to-orbit), Spiral 2 (Earth-to-Moon), and launch elements. In general, their plan for a lunar expedition involved the use of a flotilla of small, simple, and inexpensive vehicles, rather than a single elaborate vehicle.

text: A partial solar eclipse will occur on June 21, 2058. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on June 21, 2058. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Raffaele Ferrara (born October 30, 1976 in Naples) is a former Italian professional cyclist.

text: Raffaele Ferrara (born October 30, 1976 in

text: Naples

text: ) is a former Italian professional cyclist.

text: A total solar eclipse occurred on January 14, 1926. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on January 14, 1926. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Phocylides is a lunar crater located near the southwest rim of the Moon. It overlays the south rim of the crater Nasmyth to the north. To the northwest is the unusual plateau formation of Wargentin. Eastward is the merged formation Schiller, and in the southwest lies Pingré.

text: Phocylides is a

text: lunar

text: crater

text: located near the southwest rim of the

text: Moon

text: . It overlays the south rim of the crater

text: Nasmyth

text: to the north. To the northwest is the unusual plateau formation of

text: Wargentin

text: . Eastward is the merged formation

text: Schiller

text: , and in the southwest lies

text: Pingré

text: Ten of the many natural satellites in the Solar System are known to have atmospheres: Europa, Io, Callisto, Enceladus, Ganymede, Titan, Rhea, Dione, Triton and Earth's Moon. Ganymede and Europa both have very tenuous oxygen atmospheres, thought to be produced by radiation splitting the water ice present on the surface of these moons into hydrogen and oxygen. Io has an extremely thin atmosphere consisting mainly of sulfur dioxide (), arising from volcanism and sunlight-driven sublimation of surface sulfur dioxide deposits. The atmosphere of Enceladus is also extremely thin and variable, consisting mainly of water vapor, nitrogen, methane, and carbon dioxide vented from the moon's interior through cryovolcanism. The extremely thin carbon dioxide atmosphere of Callisto is thought to be replenished by sublimation from surface deposits.

text: Ten of the many natural satellites in the Solar System are known to have atmospheres:

text: Europa

text: Io

text: Callisto

text: Enceladus

text: Ganymede

text: Titan

text: Rhea

text: Dione

text: Triton

text: and

text: Earth

text: 's

text: Moon

text: . Ganymede and Europa both have very tenuous oxygen atmospheres, thought to be produced by radiation splitting the water ice present on the surface of these moons into hydrogen and oxygen. Io has an extremely thin atmosphere consisting mainly of sulfur dioxide (), arising from volcanism and sunlight-driven sublimation of surface sulfur dioxide deposits. The atmosphere of Enceladus is also extremely thin and variable, consisting mainly of water vapor, nitrogen, methane, and carbon dioxide vented from the moon's interior through

text: cryovolcanism

text: . The extremely thin carbon dioxide atmosphere of Callisto is thought to be replenished by sublimation from surface deposits.

text: At the borders of the order of Creation and the chaotic turbulence of the Wyld, their natures were changed over a great many years. Lunars follow at best a loose tribal hierarchy and ritually tattoo each other to protect themselves from the warping effects of the Wyld. This further serves to mark them as different from the rest of humanity, as the tattoos are made of moonsilver, and are often visible over much of the Lunar's body. In addition to their self-inflicted distinguishing marks, each Lunar has a "Tell," a characteristic that remains constant across all forms, further setting them apart from mortals. Lunar castes are not predetermined and inflexible, but rather are associations with phases of the moon chosen by individuals before their ritual tattooing brings them fully into Lunar society under these associations.

text: In the alternate universe, Earth-9997, of the Earth X series, Moon-Boy's skeleton is seen on the Blue Area of the Moon atop the skeleton of Devil Dinosaur and Wolverine is revealed to be a descendant of Moon-Boy.

text: In the alternate universe, Earth-9997, of the

text: Earth X

text: series, Moon-Boy's skeleton is seen on the

text: Blue Area of the Moon

text: atop the skeleton of Devil Dinosaur and

text: Wolverine

text: is revealed to be a descendant of Moon-Boy.

text: The distance between the Earth's and the Moon's surfaces is, on average, approximately . This distance is sometimes used in the same manner as the circumference of the Earth; that is, one might say that a large number of objects laid end-to-end "would reach all the way to the Moon and back two-and-a-half times".

text: The major products of volcanic processes on the Moon are evident to Earth-bound observers in the form of the lunar maria. These are large flows of basaltic lava that correspond to low-albedo surfaces covering nearly a third of the near side. Only a few percent of the farside has been affected by mare volcanism. Even before the Apollo missions confirmed it, most scientists already thought that the maria are lava-filled plains, because they have lava flow patterns and collapses attributed to lava tubes.

text: The major products of

text: volcanic processes

text: on the Moon are evident to Earth-bound observers in the form of the

text: lunar maria

text: . These are large flows of

text: basalt

text: ic

text: lava

text: that correspond to low-

text: albedo

text: surfaces covering nearly a third of the near side. Only a few percent of the farside has been affected by mare volcanism. Even before the Apollo missions confirmed it, most scientists already thought that the maria are lava-filled plains, because they have

text: lava flow

text: patterns and collapses attributed to

text: lava tube

text: s.

text: In the 1969 Condon Committee UFO report, astronomer William K. Hartmann thought the green fireballs might be explained by lunar material ejected during recent meteor impacts on the Moon's surface . Hartmann's reasoning was that such ejected lunar meteors could account for the abnormally low velocities calculated for the green fireballs by LaPaz of about Earth's escape velocity, that is, much lower than normal meteor velocities. Hartmann further claimed, without explanation or elaboration, that "the predicted characteristics match those of the 'green fireball episode'."

text: In the 1969

text: Condon Committee

text: UFO report, astronomer

text: William K. Hartmann

text: thought the green fireballs might be explained by lunar material ejected during recent meteor impacts on the Moon's surface . Hartmann's reasoning was that such ejected lunar meteors could account for the abnormally low velocities calculated for the green fireballs by LaPaz of about Earth's

text: escape velocity

text: , that is, much lower than normal meteor velocities. Hartmann further claimed, without explanation or elaboration, that "the predicted characteristics match those of the 'green fireball episode'."

text: A partial solar eclipse occurred on December 15, 1982. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on December 15, 1982. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The next morning, flight day five, Young and Duke ate breakfast and began preparations for the first extra-vehicular activity (EVA), or moonwalk. After the pair donned and pressurized their space suits and depressurized the Lunar Module cabin, Young climbed out onto the "porch" of the LM, a small platform above the ladder. Duke handed Young a jettison bag full of trash to dispose of on the surface. Young then lowered the equipment transfer bag (ETB), containing equipment for use during the EVA, to the surface. Young descended the ladder and, upon setting foot on the lunar surface, became the ninth human to walk on the Moon. Upon stepping onto the surface, Young expressed his sentiments about being there: "There you are: Mysterious and Unknown Descartes. Highland plains. Apollo 16 is gonna change your image. I'm sure glad they got ol' Brer Rabbit, here, back in the briar patch where he belongs." Duke soon descended the ladder and joined Young on the surface, becoming the tenth and youngest human to walk on the Moon, at age 36. After setting foot on the lunar surface, Duke expressed his excitement, commenting: "Fantastic! Oh, that first foot on the lunar surface is super, Tony!" The pair's first task of the moonwalk was to unload the Lunar Roving Vehicle, the Far Ultraviolet Camera/Spectrograph (UVC), and other equipment, from the Lunar Module. This was done without problems. On first driving the lunar rover, Young discovered that the rear steering was not working. He alerted Mission Control to the problem before setting up the television camera and planting the flag of the United States with Duke. The day's next task was to deploy the Apollo Lunar Surface Experiments Package (ALSEP); while they were parking the lunar rover, on which the TV camera was mounted, to observe the deployment, the rear steering began functioning without explanation. While deploying a heat-flow experiment (that had burned up with the Lunar Module Aquarius on Apollo 13 and had been attempted with limited success on Apollo 15), a cable was inadvertently snapped after getting caught around Young's foot. After ALSEP deployment, they collected samples in the vicinity. About four hours after the beginning of EVA-1, they mounted the lunar rover and drove to the first geologic stop, Plum Crater, a  crater on the rim of Flag crater, about  across. There, at a distance of  from the LM, they sampled material from the vicinity of Flag Crater, which scientists believed penetrated through the upper regolith layer to the underlying Cayley Formation. It was there that Young retrieved, at the request of Mission Control, the largest rock returned by an Apollo mission, a breccia nicknamed Big Muley after mission geology principal investigator William R. Muehlberger. The next stop of the day was Buster Crater, about  from the LM. There, Duke took pictures of Stone Mountain and South Ray Crater while Young deployed a magnetic field experiment. At that point, scientists began to reconsider their pre-mission hypothesis that Descartes had been the setting of ancient volcanic activity, as the two astronauts had yet to find any volcanic material. Following their stop at Buster, Young did a demonstration drive of the lunar rover while Duke filmed with a 16 mm movie camera. After completing more tasks at the ALSEP, they returned to the LM to close out the moonwalk. They reentered the LM 7 hours, 6 minutes, and 56 seconds after the start of the EVA. Once inside, they pressurized the LM cabin, went through a half-hour briefing with scientists in Mission Control, and configured the cabin for the sleep period.

text: The next morning, flight day five, Young and Duke ate breakfast and began preparations for the first extra-vehicular activity (EVA), or moonwalk. After the pair donned and pressurized their space suits and depressurized the Lunar Module cabin, Young climbed out onto the "porch" of the LM, a small platform above the ladder. Duke handed Young a jettison bag full of trash to dispose of on the surface. Young then lowered the equipment transfer bag (ETB), containing equipment for use during the EVA, to the surface. Young descended the ladder and, upon setting foot on the lunar surface, became the ninth human to walk on the Moon. Upon stepping onto the surface, Young expressed his sentiments about being there: "There you are: Mysterious and Unknown Descartes. Highland plains. Apollo 16 is gonna change your image. I'm sure glad they got ol'

text: Brer Rabbit

text: , here, back in the briar patch where he belongs." Duke soon descended the ladder and joined Young on the surface, becoming the tenth and youngest human to walk on the Moon, at age 36. After setting foot on the lunar surface, Duke expressed his excitement, commenting: "Fantastic! Oh, that first foot on the lunar surface is super,

text: Tony

text: !" The pair's first task of the moonwalk was to unload the Lunar Roving Vehicle, the

text: Far Ultraviolet Camera/Spectrograph

text: (UVC), and other equipment, from the Lunar Module. This was done without problems. On first driving the lunar rover, Young discovered that the rear steering was not working. He alerted Mission Control to the problem before setting up the television camera and planting the

text: flag of the United States

text: with Duke. The day's next task was to deploy the

entity_name: Apollo Lunar Surface Experiments Package

text: Apollo Lunar Surface Experiments Package

text: (ALSEP); while they were parking the lunar rover, on which the TV camera was mounted, to observe the deployment, the rear steering began functioning without explanation. While deploying a heat-flow experiment (that had burned up with the Lunar Module Aquarius on Apollo 13 and had been attempted with limited success on Apollo 15), a cable was inadvertently snapped after getting caught around Young's foot. After ALSEP deployment, they collected samples in the vicinity. About four hours after the beginning of EVA-1, they mounted the lunar rover and drove to the first geologic stop, Plum Crater, a  crater on the rim of

text: Flag crater

text: , about  across. There, at a distance of  from the LM, they sampled material from the vicinity of Flag Crater, which scientists believed penetrated through the upper

text: regolith

text: layer to the underlying Cayley Formation. It was there that Young retrieved, at the request of Mission Control, the largest rock returned by an Apollo mission, a

text: breccia

text: nicknamed

text: Big Muley

text: after mission geology principal investigator

text: William R. Muehlberger

text: . The next stop of the day was Buster Crater, about  from the LM. There, Duke took pictures of Stone Mountain and South Ray Crater while Young deployed a

text: magnetic field

text: experiment. At that point, scientists began to reconsider their pre-mission hypothesis that Descartes had been the setting of ancient volcanic activity, as the two astronauts had yet to find any volcanic material. Following their stop at Buster, Young did a demonstration drive of the lunar rover while Duke filmed with a

text: 16 mm

text: movie camera. After completing more tasks at the ALSEP, they returned to the LM to close out the moonwalk. They reentered the LM 7 hours, 6 minutes, and 56 seconds after the start of the EVA. Once inside, they pressurized the LM cabin, went through a half-hour briefing with scientists in Mission Control, and configured the cabin for the sleep period.

text: The story is set during the reign of Queen Elizabeth I, a period of religious conflict in England. Not only was there the threat of a Catholic resurgence but there were also disputes within the Protestant Church. When Gonsales first encounters the Lunars he exclaims "Jesu Maria", at which the Lunars fall to their knees, but although they revere the name of Jesus they are unfamiliar with the name Maria, suggesting that they are Protestants rather than Catholics; Poole is of the same opinion: "their lack of reaction to the name of Mary suggests that they have not fallen into the errors of the Catholic Church, despite some otherwise rather Catholic-looking institutions on the moon". Beginning in the 1580s, when Godwin was a student at Oxford University, many publications criticising the governance of the established Church of England circulated widely, until in 1586 censorship was introduced, resulting in the Martin Marprelate controversy. Martin Marprelate was the name used by the anonymous author or authors of the illegal tracts attacking the Church published between 1588 and 1589. A number of commentators, including Grant McColley, have suggested that Godwin strongly objected to the imposition of censorship, expressed in Gonsales's hope that the publication of his account may not prove "prejudicial to the Catholic faith". John Clark has suggested that the Martin Marprelate controversy may have inspired Godwin to give the name Martin to the Lunar's god, but as a bishop of the Church of England it is perhaps unlikely that he was generally sympathetic to the Martin Marprelate position. Critics do not agree on the precise denomination of Godwin's Lunars. In contrast with Clark and Poole, David Cressy argues that the Lunars falling to their knees after Gonsales's exclamation (a similar ritual takes place at the court of Irdonozur) is evidence of "a fairly mechanical form of religion (as most of Godwin's Protestant contemporaries judged Roman Catholicism)".

text: The story is set during the reign of Queen

text: Elizabeth I

text: , a period of religious conflict in England. Not only was there the threat of a

text: Catholic

text: resurgence but there were also disputes within the

text: Protestant

text: Church. When Gonsales first encounters the Lunars he exclaims "Jesu Maria", at which the Lunars fall to their knees, but although they revere the name of Jesus they are unfamiliar with the name Maria, suggesting that they are Protestants rather than Catholics; Poole is of the same opinion: "their lack of reaction to the name of Mary suggests that they have not fallen into the errors of the Catholic Church, despite some otherwise rather Catholic-looking institutions on the moon". Beginning in the 1580s, when Godwin was a student at Oxford University, many publications criticising the governance of the established

text: Church of England

text: circulated widely, until in 1586 censorship was introduced, resulting in the

text: Martin Marprelate

text: controversy. Martin Marprelate was the name used by the anonymous author or authors of the illegal tracts attacking the Church published between 1588 and 1589. A number of commentators, including Grant McColley, have suggested that Godwin strongly objected to the imposition of censorship, expressed in Gonsales's hope that the publication of his account may not prove "prejudicial to the Catholic faith". John Clark has suggested that the Martin Marprelate controversy may have inspired Godwin to give the name Martin to the Lunar's god, but as a bishop of the Church of England it is perhaps unlikely that he was generally sympathetic to the Martin Marprelate position. Critics do not agree on the precise denomination of Godwin's Lunars. In contrast with Clark and Poole,

text: David Cressy

text: argues that the Lunars falling to their knees after Gonsales's exclamation (a similar ritual takes place at the court of Irdonozur) is evidence of "a fairly mechanical form of religion (as most of Godwin's Protestant contemporaries judged Roman Catholicism)".

text: Life conditions of the people of  the Kingdom of the Two Sicilies are illustrated also by Raffaele De Cesare, who reports  the lack of interest from the king of Naples Ferdinand II to do useful works to change the neglected conditions of public hygiene, particularly in the provinces where existed scarsity of sewer systems and often water shortage.

text: Life conditions of the people of  the

text: Kingdom of the Two Sicilies

text: are illustrated also by Raffaele De Cesare, who reports  the lack of interest from the king of Naples

text: Ferdinand II

text: to do useful works to change the neglected conditions of public hygiene, particularly in the provinces where existed scarsity of sewer systems and often water shortage.

text: If a cataclysmic cratering event truly occurred on the Moon, the Earth would have been affected as well. Extrapolating lunar cratering rates  to Earth at this time suggests that the following number of craters would have formed:

text: An annular solar eclipse occurred on May 30, 1984. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: An

text: annular

text: solar eclipse

text: occurred on May 30, 1984. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: , thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's

text: apparent diameter

text: is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an

text: annulus

text: (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.

text: In the case of a planet's moon, the synodic period usually means the Sun-synodic period, namely, the time it takes the moon to complete its illumination phases, completing the solar phases for an astronomer on the planet's surface. The Earth's motion does not determine this value for other planets because an Earth observer is not orbited by the moons in question. For example, Deimos's synodic period is 1.2648 days, 0.18% longer than Deimos's sidereal period of 1.2624 d.

text: In the case of a planet's

text: moon

text: , the synodic period usually means the Sun-synodic period, namely, the time it takes the moon to complete its illumination phases, completing the solar phases for an astronomer on the planet's surface. The Earth's motion does not determine this value for other planets because an Earth observer is not orbited by the moons in question. For example,

text: Deimos

text: 's synodic period is 1.2648 days, 0.18% longer than Deimos's sidereal period of 1.2624 d.

text: Many Solar System objects are known to possess satellite systems, though their origin is still unclear.  Notable examples include the largest satellite system, the Jovian system, with 67 known moons (including the large Galilean moons)  and the Saturnian System with 62 known moons (and the most visible ring system in the Solar System).  Both satellite systems are large and diverse.  In fact all of the giant planets of the Solar System possess large satellite systems as well as planetary rings, and it is inferred that this is a general pattern.  Several objects farther from the Sun also have satellite systems consisting of multiple moons, including the complex Plutonian system where multiple objects orbit a common center of mass, as well as many asteroids and plutinos.  Apart from the Earth-Moon system and Mars' system of two tiny natural satellites, the other terrestrial planets are generally not considered satellite systems, although some have been orbited by artificial satellites originating from Earth.

text: Many Solar System objects are known to possess satellite systems, though their origin is still unclear.  Notable examples include the largest satellite system, the Jovian system, with

text: 67 known moons

text: (including the large

text: Galilean moons

text: )  and the Saturnian System with

text: 62 known moons

text: (and the most visible ring system in the Solar System).  Both satellite systems are large and diverse.  In fact all of the giant planets of the Solar System possess large satellite systems as well as planetary rings, and it is inferred that this is a general pattern.  Several objects farther from the Sun also have satellite systems consisting of multiple moons, including the complex Plutonian system where multiple objects orbit a common

text: center of mass

text: , as well as many asteroids and plutinos.  Apart from the Earth-Moon system and Mars' system of two tiny natural satellites, the other terrestrial planets are generally not considered satellite systems, although some have been orbited by artificial satellites originating from Earth.

text: Boss is a lunar impact crater that is located along the northeast rim of the Moon's near side. Due to its location, the crater is viewed from the side by observers on the Earth, and its visibility is subject to libration effects.

text: Boss is a

text: lunar

text: impact crater

text: that is located along the northeast rim of the

text: Moon

text: 's near side. Due to its location, the crater is viewed from the side by observers on the

text: Earth

text: , and its visibility is subject to

text: libration

text: effects.

text: The Moon's axial tilt with respect to the ecliptic is only 1.5424°, much less than the 23.44° of Earth. Because of this, the Moon's solar illumination varies much less with season, and topographical details play a crucial role in seasonal effects. From images taken by Clementine in 1994, it appears that four mountainous regions on the rim of Peary Crater at the Moon's north pole may remain illuminated for the entire lunar day, creating peaks of eternal light. No such regions exist at the south pole. Similarly, there are places that remain in permanent shadow at the bottoms of many polar craters, and these dark craters are extremely cold: Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at  and just  close to the winter solstice in north polar Hermite Crater. This is the coldest temperature in the Solar System ever measured by a spacecraft, colder even than the surface of Pluto. Average temperatures of the Moon's surface are reported, but temperatures of different areas will vary greatly depending upon whether it is in sunlight or shadow.

text: The Moon's

text: axial tilt

text: with respect to the

text: ecliptic

text: is only 1.5424°, much less than the 23.44° of Earth. Because of this, the Moon's solar illumination varies much less with season, and topographical details play a crucial role in seasonal effects. From images taken by

text: Clementine

text: in 1994, it appears that four mountainous regions on the rim of

text: Peary Crater

text: at the Moon's north pole may remain illuminated for the entire

text: lunar day

text: , creating

text: peaks of eternal light

text: . No such regions exist at the south pole. Similarly, there are places that remain in permanent shadow at the bottoms of many polar craters, and these dark craters are extremely cold:

text: Lunar Reconnaissance Orbiter

text: measured the lowest summer temperatures in craters at the southern pole at  and just  close to the winter solstice in north polar

text: Hermite Crater

text: . This is the coldest temperature in the Solar System ever measured by a spacecraft, colder even than the surface of

text: Pluto

text: . Average temperatures of the Moon's surface are reported, but temperatures of different areas will vary greatly depending upon whether it is in sunlight or shadow.

text: Barnard is a lunar crater that is located near the eastern limb of the Moon. It is attached to the southeast rim of the large crater Humboldt, and Abel lies directly to the south. To the northeast is the crater Curie, while to the southeast is the Mare Australe.

text: Barnard is a

text: lunar

text: crater

text: Moon

text: . It is attached to the southeast rim of the large crater

text: Humboldt

text: , and

text: Abel

text: lies directly to the south. To the northeast is the crater

text: Curie

text: , while to the southeast is the

text: Mare Australe

text: The ongoing Lunar Laser Ranging Experiment measures the distance between Earth and the Moon using laser ranging. Lasers on Earth are aimed at retroreflectors planted on the Moon during the Apollo program (11, 14, and 15) and the two Lunokhod missions.The time for the reflected light to return is measured.

text: The ongoing Lunar Laser Ranging Experiment measures the

text: distance

text: between

text: Earth

text: and the

text: Moon

text: using

text: laser ranging

text: Laser

text: s on Earth are aimed at

text: retroreflector

text: s planted on the Moon during the

text: Apollo program

text: , and

text: ) and the two

text: Lunokhod

text: missions.The time for the reflected light to return is measured.

text: Current technology limits the testing of important Rare Earth Criteria: surface water, tectonic plates, a large moon and biosignatures are currently undetectable. Though planets the size of Earth are difficult to detect and classify, scientists now think that rocky planets are common around Sun-like stars. The Earth Similarity Index (ESI) of mass, radius and temperature provides a means of measurement, but falls short of the full Rare Earth criteria.

text: Current technology limits the testing of important Rare Earth Criteria: surface water, tectonic plates, a large moon and

text: biosignature

text: s are currently undetectable. Though planets the size of Earth are difficult to detect and classify, scientists now think that rocky planets are common around Sun-like stars. The

text: Earth Similarity Index

text: (ESI) of mass, radius and temperature provides a means of measurement, but falls short of the full Rare Earth criteria.

text: Over the centuries, many scientific hypotheses have been advanced concerning the origin of Earth's Moon. One of the earliest was the so-called binary accretion model, which concluded that the Moon accreted from material in orbit around the Earth left over from its formation. Another, the fission model, was developed by George Darwin (son of Charles Darwin), who noted that, as the Moon is gradually receding from the Earth at a rate of about 4 cm per year, so at one point in the distant past it must have been part of the Earth, but was flung outward by the momentum of Earth's then–much faster rotation. This hypothesis is also supported by the fact that the Moon's density, while less than Earth's, is about equal to that of Earth's rocky mantle, suggesting that, unlike the Earth, it lacks a dense iron core. A third hypothesis, known as the capture model, suggested that the Moon was an independently orbiting body that had been snared into orbit by Earth's gravity.

text: Over the centuries, many scientific hypotheses have been advanced concerning the origin of

text: Earth's Moon

text: . One of the earliest was the so-called

text: binary accretion model

text: , which concluded that the Moon accreted from material in orbit around the Earth left over from its formation. Another, the

text: fission model

text: , was developed by

text: George Darwin

text: (son of

text: Charles Darwin

text: ), who noted that, as the Moon is gradually receding from the Earth at a rate of about 4 cm per year, so at one point in the distant past it must have been part of the Earth, but was flung outward by the momentum of Earth's then–much faster rotation. This hypothesis is also supported by the fact that the Moon's density, while less than Earth's, is about equal to that of Earth's rocky

text: mantle

text: , suggesting that, unlike the Earth, it lacks a dense iron core. A third hypothesis, known as the

text: capture model

text: , suggested that the Moon was an independently orbiting body that had been snared into orbit by Earth's gravity.

text: As a result of the siege of Paris and the Commune episode, many aqueducts had been destroyed, and the price of water, already higher than normal, went up considerably. Because of this, most of the poor had to pay for water. Moreover most of the water carted about by vendors was drawn from the Seine river and was thus highly likely to be dirty; all the waste water from the streets and many of the sewers draining directly into it. It was therefore safer to drink beer or other alcoholic beverages and almost as cheap as water. The temptation to take to liquor was strong among the lower classes, and it was considered a moral duty to keep them from falling into alcoholism.  Even today, when water and hygiene are not a problem for the majority of Parisians, these fountains are often the only sources of free water for the homeless.

text: As a result of the siege of Paris and the

text: Commune

text: episode, many

text: aqueduct

text: s had been destroyed, and the price of water, already higher than normal, went up considerably. Because of this, most of the poor had to pay for water. Moreover most of the water carted about by vendors was drawn from the Seine river and was thus highly likely to be dirty; all the waste water from the streets and many of the sewers draining directly into it. It was therefore safer to drink beer or other alcoholic beverages and almost as cheap as water. The temptation to take to liquor was strong among the lower classes, and it was considered a moral duty to keep them from falling into

text: alcoholism

text: .  Even today, when water and hygiene are not a problem for the majority of Parisians, these fountains are often the only sources of free water for the

text: homeless

text: In the second book, Hipparchus starts from the opposite extreme assumption: he assigns a (minimum) distance to the Sun of 490 Earth radii. This would correspond to a parallax of 7', which is apparently the greatest parallax that Hipparchus thought would not be noticed (for comparison: the typical resolution of the human eye is about 2'; Tycho Brahe made naked eye observation with an accuracy down to 1'). In this case, the shadow of the Earth is a cone rather than a cylinder as under the first assumption. Hipparchus observed (at lunar eclipses) that at the mean distance of the Moon, the diameter of the shadow cone is 2+½ lunar diameters. That apparent diameter is, as he had observed, 360/650 degrees. With these values and simple geometry, Hipparchus could determine the mean distance; because it was computed for a minimum distance of the Sun, it is the maximum mean distance possible for the Moon. With his value for the eccentricity of the orbit, he could compute the least and greatest distances of the Moon too. According to Pappus, he found a least distance of 62, a mean of 67+1/3, and consequently a greatest distance of 72+2/3 Earth radii. With this method, as the parallax of the Sun decreases (i.e., its distance increases), the minimum limit for the mean distance is 59 Earth radii – exactly the mean distance that Ptolemy later derived.

text: In the second book, Hipparchus starts from the opposite extreme assumption: he assigns a (minimum) distance to the Sun of 490 Earth radii. This would correspond to a parallax of 7', which is apparently the greatest parallax that Hipparchus thought would not be noticed (for comparison: the typical resolution of the human eye is about 2';

text: Tycho Brahe

text: made naked eye observation with an accuracy down to 1'). In this case, the shadow of the Earth is a

text: cone

text: rather than a

text: cylinder

text: as under the first assumption. Hipparchus observed (at lunar eclipses) that at the mean distance of the Moon, the diameter of the shadow cone is 2+½ lunar diameters. That apparent diameter is, as he had observed, 360/650 degrees. With these values and simple geometry, Hipparchus could determine the mean distance; because it was computed for a minimum distance of the Sun, it is the maximum mean distance possible for the Moon. With his value for the eccentricity of the orbit, he could compute the least and greatest distances of the Moon too. According to Pappus, he found a least distance of 62, a mean of 67+1/3, and consequently a greatest distance of 72+2/3 Earth radii. With this method, as the parallax of the Sun decreases (i.e., its distance increases), the minimum limit for the mean distance is 59 Earth radii – exactly the mean distance that Ptolemy later derived.

text: The Earth and the Moon form a case in point, partly because the Moon is unusually large (just over 1% of the mass of the Earth) in relation to its parent planet compared with other natural satellites. There are also very precise data available for the Earth–Moon system, particularly from the Lunar Laser Ranging Experiment (LLR).

text: The Earth and the Moon form a case in point, partly because the Moon is unusually large (just over 1% of the mass of the Earth) in relation to its parent planet compared with other natural satellites. There are also very precise data available for the Earth–Moon system, particularly from the

text: Lunar Laser Ranging Experiment

text: (LLR).

text: Jeans is a lunar crater along the southeastern limb of the Moon. The majority of this formation lies on the far side with respect to the Earth, but favorable librations can bring the entire crater into view. Despite this, however, this crater is viewed from the side from Earth, limiting the amount of detail that can be observed.

text: Jeans is a

text: lunar

text: crater

text: along the southeastern limb of the

text: Moon

text: . The majority of this formation lies on the

text: far side

text: with respect to the

text: Earth

text: , but favorable

text: libration

text: s can bring the entire crater into view. Despite this, however, this crater is viewed from the side from Earth, limiting the amount of detail that can be observed.

text: The lunar elevator could also be used to transport supplies and materials from the surface of the moon into the Earth’s orbit and vice versa.  According to Jerome Pearson, many of the Moon's material resources can be extracted and sent into Earth orbit more easily than if they were launched from the Earth's surface. For example, lunar regolith itself could be used as massive material to shield space stations or crewed spacecraft on long missions from solar flares, Van Allen radiation, and other kinds of cosmic radiation. The Moon's naturally occurring metals and minerals could be mined and used for construction.  Lunar deposits of silicon, which could be used to build solar panels for massive satellite solar power stations, seem particularly promising.

text: The lunar elevator could also be used to transport supplies and materials from the surface of the moon into the Earth’s orbit and vice versa.  According to Jerome Pearson, many of the Moon's material resources can be extracted and sent into Earth orbit more easily than if they were launched from the Earth's surface. For example, lunar

text: regolith

text: itself could be used as massive material to shield space stations or crewed spacecraft on long missions from

text: solar flare

text: s,

text: Van Allen radiation

text: , and other kinds of

text: cosmic radiation

text: . The Moon's naturally occurring metals and minerals could be mined and used for construction.  Lunar deposits of silicon, which could be used to build solar panels for massive

text: satellite solar power

text: stations, seem particularly promising.

text: Whilst studying the logo of the Apollo 13 mission Cantwell had an idea which resulted in a unique photographic project. Apollo 13 was the 7th manned mission in the Apollo program and was intended to be the third such mission to the moon. However, it is probably best remembered as the first in the Apollo program to require an emergency abort. The moon landing was abandoned after an oxygen tank exploded en route to the moon, approximately 200,000 miles from Earth, which crippled the service module necessitating emergency makeshift repairs to the lithium containers so that carbon dioxide could be eliminated to ensure adequate oxygen in the module, and also resulted in limited power, loss of cabin heat, shortage of drinking water and before it was possible to return the crew safely to Earth.  Jim Lovell, the Apollo 13 commander, later called the mission, “a successful failure”.

text: Whilst studying the logo of the Apollo 13 mission Cantwell had an idea which resulted in a unique photographic project. Apollo 13 was the 7th manned mission in the Apollo program and was intended to be the third such mission to the moon. However, it is probably best remembered as the first in the Apollo program to require an emergency abort. The

text: moon landing

text: was abandoned after an oxygen tank exploded en route to the moon, approximately 200,000 miles from Earth, which crippled the service module necessitating emergency makeshift repairs to the

text: lithium

text: containers so that

text: carbon dioxide

text: could be eliminated to ensure adequate

text: oxygen

text: in the module, and also resulted in limited power, loss of cabin heat, shortage of drinking water and before it was possible to return the crew safely to Earth.

text: Jim Lovell

text: , the Apollo 13 commander, later called the mission, “a successful failure”.

text: Various distance definitions are possible between objects. For example, between celestial bodies one should not confuse the surface-to-surface distance and the center-to-center distance. If the former is much less than the latter, as for a low earth orbit, the first tends to be quoted (altitude), otherwise, e.g. for the Earth-Moon distance, the latter.

text: Various distance definitions are possible between objects. For example, between celestial bodies one should not confuse the surface-to-surface distance and the center-to-center distance. If the former is much less than the latter, as for a

text: low earth orbit

text: , the first tends to be quoted (altitude), otherwise, e.g. for the Earth-Moon distance, the latter.

text: Among the most prominent features of the Moon's sky is Earth. Its visible diameter (1.9°) is four times the diameter of the Moon as seen from Earth, although because the Moon's orbit is eccentric, Earth's apparent size in the sky varies by about 5% either way (ranging between 1.8° and 2.0° in diameter). Earth shows phases, just like the Moon does for the terrestrial observer, but they are opposite: when the terrestrial observer sees the full Moon, the lunar observer sees a "new Earth", and vice versa. Earth's albedo is three times as high as that of the Moon (due in part to its whitish cloud cover), and coupled with the increased area the full Earth glows over 50 times brighter than the full Moon at zenith does for the terrestrial observer. This Earth light is bright enough that it is visible across the Moon's unlit half from Earth with the naked eye, a phenomenon known as earthshine.

text: Among the most prominent features of the Moon's sky is Earth. Its visible diameter (1.9°) is four times the diameter of the Moon as seen from Earth, although because the Moon's orbit is eccentric, Earth's apparent size in the sky varies by about 5% either way (ranging between 1.8° and 2.0° in diameter). Earth shows

text: phases

text: , just like the Moon does for the terrestrial observer, but they are opposite: when the terrestrial observer sees the full Moon, the lunar observer sees a "new Earth", and vice versa. Earth's

text: albedo

text: is three times as high as that of the Moon (due in part to its whitish cloud cover), and coupled with the increased area the full Earth glows over 50 times brighter than the full Moon at zenith does for the terrestrial observer. This Earth light is bright enough that it is visible across the Moon's unlit half from Earth with the naked eye, a phenomenon known as

text: earthshine

text: In 1973, George W. Moore of the USGS and R. C. Bostrom presented evidence for a general westward drift of the Earth's lithosphere with respect to the mantle.  He concluded that tidal forces (the tidal lag or "friction") caused by the Earth's rotation and the forces acting upon it by the Moon are a driving force for plate tectonics.  As the Earth spins eastward beneath the moon, the moon's gravity ever so slightly pulls the Earth's surface layer back westward, just as proposed by Alfred Wegener (see above). In a more recent 2006 study, scientists reviewed and advocated these earlier proposed ideas. It has also been suggested recently in  that this observation may also explain why Venus and Mars have no plate tectonics, as Venus has no moon and Mars' moons are too small to have significant tidal effects on the planet. In a recent paper, it was suggested that, on the other hand, it can easily be observed that many plates are moving north and eastward, and that the dominantly westward motion of the Pacific Ocean basins derives simply from the eastward bias of the Pacific spreading center (which is not a predicted manifestation of such lunar forces). In the same paper the authors admit, however, that relative to the lower mantle, there is a slight westward component in the motions of all the plates. They demonstrated though that the westward drift, seen only for the past 30 Ma, is attributed to the increased dominance of the steadily growing and accelerating Pacific plate. The debate is still open.

text: In 1973, George W. Moore of the

text: USGS

text: and R. C. Bostrom presented evidence for a general westward drift of the Earth's lithosphere with respect to the mantle.  He concluded that tidal forces (the tidal lag or "friction") caused by the Earth's rotation and the forces acting upon it by the Moon are a driving force for plate tectonics.  As the Earth spins eastward beneath the moon, the moon's gravity ever so slightly pulls the Earth's surface layer back westward, just as proposed by Alfred Wegener (see above). In a more recent 2006 study, scientists reviewed and advocated these earlier proposed ideas. It has also been suggested recently in  that this observation may also explain why

text: Venus

text: and

text: Mars

text: have no plate tectonics, as Venus has no moon and Mars' moons are too small to have significant tidal effects on the planet. In a recent paper, it was suggested that, on the other hand, it can easily be observed that many plates are moving north and eastward, and that the dominantly westward motion of the Pacific Ocean basins derives simply from the eastward bias of the Pacific spreading center (which is not a predicted manifestation of such lunar forces). In the same paper the authors admit, however, that relative to the lower mantle, there is a slight westward component in the motions of all the plates. They demonstrated though that the westward drift, seen only for the past 30 Ma, is attributed to the increased dominance of the steadily growing and accelerating Pacific plate. The debate is still open.

text: The near side of the Moon is the lunar hemisphere that is permanently turned towards the Earth, whereas the opposite side is the far side of the Moon. Only one side of the Moon is visible from Earth because the Moon rotates about its spin axis at the same rate that the Moon orbits the Earth, a situation known as synchronous rotation or tidal locking. The Moon is directly illuminated by the Sun, and the cyclically varying viewing conditions cause the lunar phases. The unilluminated portions of the Moon can sometimes be dimly seen as a result of earthshine, which is sunlight reflected off the surface of the Earth and onto the Moon. Since the Moon's orbit is both somewhat elliptical, and inclined to its equatorial plane, libration allows up to 59% of the Moon's surface to be viewed from Earth (but only half at any instant from any point).

text: The near side of the Moon is the

text: lunar

text: hemisphere that is permanently turned towards the

text: Earth

text: , whereas the opposite side is the

text: far side of the Moon

text: . Only one side of the

text: Moon

text: is visible from Earth because the Moon rotates about its spin axis at the same rate that the Moon orbits the Earth, a situation known as

text: synchronous rotation

text: or

text: tidal locking

text: . The Moon is directly illuminated by the

text: Sun

text: , and the cyclically varying viewing conditions cause the

text: lunar phase

text: s. The unilluminated portions of the Moon can sometimes be dimly seen as a result of

text: earthshine

text: , which is sunlight reflected off the surface of the Earth and onto the Moon. Since the

text: Moon's orbit

text: is both somewhat elliptical, and inclined to its

text: equatorial plane

text: libration

text: allows up to 59% of the Moon's surface to be viewed from Earth (but only half at any instant from any point).

text: Despite this, Chinese thinkers of the Middle Ages proposed some hypotheses which are in accordance with modern principles of science. Yang Hui provided theoretical proof for the proposition that the complements of the parallelograms which are about the diameter of any given parallelogram are equal to one another. Sun Sikong (1015–1076) proposed the idea that rainbows were the result of the contact between sunlight and moisture in the air, while Shen Kuo (1031–1095) expanded upon this with description of atmospheric refraction. Shen believed that rays of sunlight refracted before reaching the surface of the earth, hence the appearance of the observed sun from earth did not match its exact location. Coinciding with the astronomical work of his colleague Wei Pu, Shen and Wei realized that the old calculation technique for the mean sun was inaccurate compared to the apparent sun, since the latter was ahead of it in the accelerated phase of motion, and behind it in the retarded phase. Shen supported and expanded upon beliefs earlier proposed by Han Dynasty (202 BCE–202 CE) scholars such as Jing Fang (78–37 BCE) and Zhang Heng (78–139 CE) that lunar eclipse occurs when the earth obstructs the sunlight traveling towards the moon, a solar eclipse is the moon's obstruction of sunlight reaching earth, the moon is spherical like a ball and not flat like a disc, and moonlight is merely sunlight reflected from the moon's surface. Shen also explained that the observance of a full moon occurred when the sun's light was slanting at a certain degree and that crescent phases of the moon proved that the moon was spherical, using a metaphor of observing different angles of a silver ball with white powder thrown onto one side. It should be noted that, although the Chinese accepted the idea of spherical-shaped heavenly bodies, the concept of a spherical earth (as opposed to a flat earth) was not accepted in Chinese thought until the works of Italian Jesuit Matteo Ricci (1552–1610) and Chinese astronomer Xu Guangqi (1562–1633) in the early 17th century.

text: Despite this, Chinese thinkers of the Middle Ages proposed some hypotheses which are in accordance with modern principles of science. Yang Hui provided theoretical proof for the proposition that the complements of the

text: parallelogram

text: s which are about the diameter of any given parallelogram are equal to one another. Sun Sikong (1015–1076) proposed the idea that

text: rainbow

text: s were the result of the contact between sunlight and moisture in the air, while

text: Shen Kuo

text: (1031–1095) expanded upon this with description of

text: atmospheric refraction

text: . Shen believed that rays of sunlight refracted before reaching the surface of the earth, hence the appearance of the observed sun from earth did not match its exact location. Coinciding with the astronomical work of his colleague

text: Wei Pu

text: , Shen and Wei realized that the old calculation technique for the mean sun was inaccurate compared to the apparent sun, since the latter was ahead of it in the accelerated phase of motion, and

text: behind it in the retarded phase

text: . Shen supported and expanded upon beliefs earlier proposed by

text: Han Dynasty

text: (202 BCE–202 CE) scholars such as

text: Jing Fang

text: (78–37 BCE) and

text: Zhang Heng

text: (78–139 CE) that

text: lunar eclipse

text: occurs when the earth obstructs the sunlight traveling towards the moon, a

text: solar eclipse

text: is the moon's obstruction of sunlight reaching earth, the moon is spherical like a ball and not flat like a disc, and moonlight is merely sunlight reflected from the moon's surface. Shen also explained that the observance of a full moon occurred when the sun's light was slanting at a certain degree and that crescent

text: phases of the moon

text: proved that the moon was spherical, using a metaphor of observing different angles of a silver ball with white powder thrown onto one side. It should be noted that, although the Chinese accepted the idea of spherical-shaped heavenly bodies, the concept of a

text: spherical earth

text: (as opposed to a

text: flat earth

text: ) was not accepted in Chinese thought until the works of Italian Jesuit

text: Matteo Ricci

text: (1552–1610) and Chinese astronomer

text: Xu Guangqi

text: (1562–1633) in the early 17th century.

text: Central lunar eclipses are defined as lunar eclipses where part of the Moon passes through the center of the Earth's shadow. They are the darkest eclipses and relatively rare.

text: Central lunar eclipses are defined as

text: lunar eclipses

text: where part of the Moon passes through the center of the Earth's shadow. They are the darkest eclipses and relatively rare.

text: Scientists hypothesize that some of the first water brought to Earth was delivered by asteroid impacts after the collision that produced the Moon. The presence of ice on 24 Themis supports this theory. Because of its proximity to the sun (~3.2 AU), the widespread ice on the surface of 24 Themis is somewhat unexpected. The surface ice may be replenished by a sub-surface reservoir of water or impact gardening—a lunar phenomenon in which the moon overturns surface material at a rate of 1  m/ Gyr.

text: Scientists hypothesize that some of the first water brought to

text: Earth

text: was delivered by asteroid impacts after the collision that produced the

text: Moon

text: . The presence of ice on 24 Themis supports this theory. Because of its proximity to the sun (~3.2 AU), the widespread ice on the surface of 24 Themis is somewhat unexpected. The surface ice may be replenished by a sub-surface reservoir of water or

text: impact gardening

text: —a lunar phenomenon in which the moon overturns surface material at a rate of 1  m/ Gyr.

text: A wet wipe, also known as a wet towel, or a moist towelette, is a small moistened piece of paper or cloth that often comes folded and individually wrapped for convenience. Wet wipes are used for cleaning purposes, like personal hygiene or household cleaning. Because of their failure to break down when flushed, they have been implicated by water companies as contributory to sewer blockages known as fatbergs.

text: A wet wipe, also known as a wet towel, or a moist towelette, is a small moistened piece of

text: paper

text: or

text: cloth

text: that often comes folded and individually wrapped for convenience. Wet wipes are used for cleaning purposes, like

text: personal hygiene

text: or household cleaning. Because of their failure to break down when flushed, they have been implicated by water companies as contributory to sewer blockages known as

text: fatberg

text: s.

text: Raffaele Longo (born 6 September 1977 in Naples) is a retired Italian footballer, who played as a midfielder.

text: Raffaele Longo (born 6 September 1977 in

text: Naples

text: ) is a retired

text: Italian

text: footballer

text: , who played as a

text: midfielder

text: Another more obscure version of this kata known as Aragaki-no-Seisan, bears the closest surface resemblance to the Shotokan kata Hangetsu. The Shotokan version was probably renamed when Gichin Funakoshi formed his school in Japan. Hangetsu translates to 'Half Moon' or 'Half Month' a reference to the half-moon stance used extensively and the semi-circular stepping actions in this kata. It is interesting to note the name Seisan could have been a reference to the 13-day cycle of the moons phases, and knowing this Funakoshi named the kata 'Half Moon/Month'. A more obscure and unlikely theory is that the kata was taken from a Chinese folk dance where the performer is explaining the importance of the tides as they cycle on 13-day intervals as the moon revolves around the earth.

text: Another more obscure version of this kata known as Aragaki-no-Seisan, bears the closest surface resemblance to the

text: Shotokan

text: kata Hangetsu. The Shotokan version was probably renamed when Gichin Funakoshi formed his school in

text: Japan

text: . Hangetsu translates to 'Half Moon' or 'Half Month' a reference to the half-moon stance used extensively and the semi-circular stepping actions in this kata. It is interesting to note the name Seisan could have been a reference to the 13-day cycle of the moons phases, and knowing this Funakoshi named the kata 'Half Moon/Month'. A more obscure and unlikely theory is that the kata was taken from a Chinese folk dance where the performer is explaining the importance of the tides as they cycle on 13-day intervals as the moon revolves around the earth.

text: The Soviet manned lunar programs failed to send a manned mission to the Moon. However, in 1966 Luna 9 was the first probe to achieve a soft landing and return close-up shots of the Lunar surface. Luna 16 in 1970 returned the first Soviet Lunar soil samples, while in 1970 and 1973 during the Lunokhod program two robotic rovers landed on the Moon. Lunokhod 1 explored the Lunar surface for 322 days, and Lunokhod 2 operated on the Moon about four months only but covered a third more distance. 1974 saw the end of the Soviet Moonshot, two years after the last American manned landing. Besides the manned landings, an abandoned Soviet moon program included building the moonbase "Zvezda", which was the first detailed project with developed mockups of expedition vehicles and surface modules.

text: The

text: Soviet manned lunar programs

text: failed to send a manned mission to the Moon. However, in 1966

text: Luna 9

text: was the first probe to achieve a soft landing and return close-up shots of the Lunar surface.

text: Luna 16

text: in 1970 returned the first Soviet Lunar soil samples, while in 1970 and 1973 during the

text: Lunokhod program

text: two robotic rovers landed on the Moon.

text: Lunokhod 1

text: explored the Lunar surface for 322 days, and

text: Lunokhod 2

text: operated on the Moon about four months only but covered a third more distance. 1974 saw the end of the Soviet Moonshot, two years after the last American manned landing. Besides the manned landings, an abandoned Soviet moon program included building the moonbase "

text: Zvezda

text: ", which was the first detailed project with developed mockups of expedition vehicles and surface modules.

text: A lunar conjunction is the event when the earth, moon and sun, in that order, are approximately in a straight line. (See conjunction (astronomy) for a precise definition.) It is sometimes referred to as the new moon, though in Judaism, the new moon refers to observance by earth bound individuals of the first visible crescent of the moon. The period of time between two lunar conjunctions is the synodic month, which is a basic unit in most lunar (such as the Islamic) and luni-solar (such as the Hebrew) calendars.

text: A lunar conjunction is the event when the earth, moon and sun, in that order, are approximately in a straight line. (See

text: conjunction (astronomy)

text: for a precise definition.) It is sometimes referred to as the

text: new moon

text: , though in Judaism, the new moon refers to observance by earth bound individuals of the first visible crescent of the moon. The period of time between two lunar conjunctions is the

text: synodic month

text: , which is a basic unit in most lunar (such as the

text: Islamic

text: ) and luni-solar (such as the

text: Hebrew

text: calendars

text: Fluctuations in the orbits of the moons indicate that their mean density decreases with distance from Jupiter. Callisto, the outermost and least dense of the four, has a density intermediate between ice and rock whereas Io, the innermost and densest moon, has a density intermediate between rock and iron. Callisto has an ancient, heavily cratered and unaltered ice surface and the way it rotates indicates that its density is equally distributed, suggesting that it has no rocky or metallic core but consists of a homogeneous mix of rock and ice. This may well have been the original structure of all the moons. The rotation of the three inner moons, in contrast, indicates differentiation of their interiors with denser matter at the core and lighter matter above. They also reveal significant alteration of the surface. Ganymede reveals past tectonic movement of the ice surface which required partial melting of subsurface layers. Europa reveals more dynamic and recent movement of this nature, suggesting a thinner ice crust. Finally, Io, the innermost moon, has a sulfur surface, active volcanism and no sign of ice. All this evidence suggests that the nearer a moon is to Jupiter the hotter its interior. The current model is that the moons experience tidal heating as a result of the gravitational field of Jupiter in inverse proportion to the square of their distance from the giant planet. In all but Callisto this will have melted the interior ice, allowing rock and iron to sink to the interior and water to cover the surface. In Ganymede a thick and solid ice crust then formed. In warmer Europa a thinner more easily broken crust formed. In Io the heating is so extreme that all the rock has melted and water has long ago boiled out into space.

text: Banting is a small, bowl-shaped lunar impact crater located near the middle of the Mare Serenitatis on the Earth's moon.

text: Banting is a small, bowl-shaped

text: lunar

text: impact crater

text: located near the middle of the

text: Mare Serenitatis

text: on the Earth's moon.

text: A total solar eclipse occurred on December 12, 1871. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on December 12, 1871. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Wyld is a lunar impact crater that is located on the Moon's far side, beyond the eastern limb. It lies in that portion of the lunar surface that is sometimes brought into view of the Earth under conditions of favorable libration and illumination, but even then the crater is seen from the edge and not much detail can be observed. Wyld lies to the northeast of the larger Hirayama and to the west of Saha. Attached to the northern outer rim is the small crater Fox.

text: Wyld is a

text: lunar

text: impact crater

text: that is located on the

text: Moon

text: 's

text: far side

text: , beyond the eastern limb. It lies in that portion of the lunar surface that is sometimes brought into view of the

text: Earth

text: under conditions of favorable

text: libration

text: and illumination, but even then the crater is seen from the edge and not much detail can be observed. Wyld lies to the northeast of the larger

text: Hirayama

text: and to the west of

text: Saha

text: . Attached to the northern outer rim is the small crater

text: Fox

text: A partial solar eclipse will occur on March 11, 2062. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on March 11, 2062. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The path which the sun takes among the stars is known as the ecliptic.   The moon's orbit is inclined at five degrees to the ecliptic, so it will always be within five degrees either side of it.   For  half the sidereal month (relative to the stars) the moon is below the ecliptic and for half it is above.   The point where the moon's orbit cuts that of the earth is the "node" – at the "ascending node" the moon moves from south to north and at the "descending node" it moves from north to south.   These points are where eclipses occur – hence the name.   The nodes move around the ecliptic at the rate of one circuit every 18.6 years.   The ecliptic makes the steepest angle with the horizon at the equinoxes.   The crescent moon is near the sun so it is at those times it will be seen lying on its  back.

text: The path which the sun takes among the stars is known as the

text: ecliptic

text: .   The moon's orbit is inclined at five degrees to the ecliptic, so it will always be within five degrees either side of it.   For  half the

text: sidereal month

text: (relative to the stars) the moon is below the ecliptic and for half it is above.   The point where the moon's orbit cuts that of the earth is the "node" – at the "ascending node" the moon moves from south to north and at the "descending node" it moves from north to south.   These points are where eclipses occur – hence the name.   The nodes move around the ecliptic at the rate of one circuit every 18.6 years.   The ecliptic makes the steepest angle with the horizon at the equinoxes.   The crescent moon is near the sun so it is at those times it will be seen lying on its  back.

text: Tides are the movement of water across Earth's surface caused by the combined effects of the gravitational forces exerted by the Moon, Sun, and the rotation of Earth which manifest in the local rise and fall of sea levels.  Tides are driven by the relative positions of the Earth, Sun, Moon, land formations, and relative location on Earth.In the lunar month, the highest tides occur roughly every 14 days, at the new and full moons, when the gravitational pull of the Moon and the Sun are in alignment.  These highest tides in the lunar cycle are called spring tides.

text: Tides are the movement of water across

text: Earth

text: 's surface caused by the combined effects of the gravitational forces exerted by the

text: Moon

text: Sun

text: , and the rotation of Earth which manifest in the local rise and fall of sea levels.  Tides are driven by the relative positions of the Earth, Sun, Moon, land formations, and relative location on Earth.In the lunar month, the highest tides occur roughly every 14 days, at the new and full moons, when the gravitational pull of the Moon and the Sun are in alignment.  These highest tides in the lunar cycle are called spring tides.

text: A total solar eclipse will occur on August 15, 2091. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on August 15, 2091. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Modern theories also suggest that Earth's anomalously large moon was formed catastrophically. In a paper published in Icarus in 1975, William K. Hartmann and Donald R. Davis proposed that a catastrophic near-miss by a large planetesimal early in Earth's formation approximately 4.5 billion years ago blew out rocky debris, remelted Earth and formed the Moon, thus explaining the Moon's lesser density and lack of an iron core. The impact theory does have some faults; some computer simulations show the formation of a ring or multiple moons post impact, and elements are not quite the same between the earth and moon.

text: Modern theories also suggest that Earth's anomalously large

text: moon

text: was formed catastrophically. In a paper published in Icarus in 1975,

text: William K. Hartmann

text: and

text: Donald R. Davis

text: proposed that a catastrophic near-miss by a large

text: planetesimal

text: early in Earth's formation approximately 4.5 billion years ago blew out rocky debris, remelted Earth and formed the

text: Moon

text: , thus explaining the Moon's lesser density and lack of an iron core. The impact theory does have some faults; some computer simulations show the formation of a ring or multiple moons post impact, and elements are not quite the same between the earth and moon.

text: The origin of the Moon's craters as impact features became widely accepted only in the 1940s. This realization allowed the impact history of the Moon to be gradually worked out by means of the geologic principle of superposition. That is, if a crater (or its ejecta) overlaid another, it must be the younger. The amount of erosion experienced by a crater was another clue to its age, though this is more subjective. Adopting this approach in the late 1950s, Gene Shoemaker took the systematic study of the Moon away from the astronomers and placed it firmly in the hands of the lunar geologists.

text: The origin of the Moon's craters as impact features became widely accepted only in the 1940s. This realization allowed the impact history of the Moon to be gradually worked out by means of the geologic principle of

text: superposition

text: . That is, if a crater (or its ejecta) overlaid another, it must be the younger. The amount of erosion experienced by a crater was another clue to its age, though this is more subjective. Adopting this approach in the late 1950s,

text: Gene Shoemaker

text: took the systematic study of the Moon away from the astronomers and placed it firmly in the hands of the lunar geologists.

text: A total solar eclipse occurred on July 20, 1963. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on July 20, 1963. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: A total solar eclipse will occur on April 30, 2041. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on April 30, 2041. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: The two hemispheres have distinctly different appearances, with the near side covered in multiple, large maria (Latin for 'seas,' since the earliest astronomers incorrectly thought that these plains were seas of lunar water). The far side has a battered, densely cratered appearance with few maria. Only 1% of the surface of the far side is covered by maria, compared to 31.2% on the near side. According to research analyzed by NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission, the reason for the difference is because the moon’s crust is thinner on the near side compared to the far side. The dark splotches that make up the large lunar maria are lava-filled impact basins that were created by asteroid impacts about four billion years ago. Though both sides of the moon were bombarded by similarly large impactors, the near side hemisphere crust and upper mantle was hotter than that of the far side, resulting in the larger impact craters. These larger impact craters make up the Man in the Moon references from popular mythology.

text: The two hemispheres have distinctly different appearances, with the near side covered in multiple, large

text: maria

text: (Latin for 'seas,' since the earliest astronomers incorrectly thought that these plains were seas of lunar water). The far side has a battered, densely cratered appearance with few maria. Only 1% of the surface of the far side is covered by maria, compared to 31.2% on the near side. According to research analyzed by NASA’s

text: Gravity Recovery and Interior Laboratory

text: (GRAIL) mission, the reason for the difference is because the moon’s crust is thinner on the near side compared to the far side. The dark splotches that make up the large lunar maria are lava-filled impact basins that were created by asteroid impacts about four billion years ago. Though both sides of the moon were bombarded by similarly large impactors, the near side hemisphere crust and upper mantle was hotter than that of the far side, resulting in the larger impact craters. These larger impact craters make up the

text: Man in the Moon

text: references from popular mythology.

text: This is the smaller world, with 0.76 Earth masses at 94% of its diameter, and 85% of its surface gravity. The mean surface temperature is only +5 °C. Because most of this chilly planet's water is locked in permafrost and glaciers, the atmosphere (which has a sea-level pressure of 0.7 bar, equivalent to about 3,650 m altitude on Earth) is not only thin but also uncomfortably dry. From the hemisphere where the companion world Genji can be seen it hangs in the sky as a globe of 6° 20' diameter, and when full gives over 320 times the light of the full Moon as seen from Earth.

text: This is the smaller world, with 0.76 Earth masses at 94% of its diameter, and 85% of its surface gravity. The mean surface temperature is only +5 °C. Because most of this chilly planet's water is locked in

text: permafrost

text: and glaciers, the atmosphere (which has a sea-level pressure of 0.7 bar, equivalent to about 3,650 m altitude on Earth) is not only thin but also uncomfortably dry. From the hemisphere where the companion world Genji can be seen it hangs in the sky as a globe of 6° 20' diameter, and when full gives over 320 times the light of the full Moon as seen from Earth.

text: Chaplygin is a large lunar impact crater that lies on the far side of the Moon. It is located to the southeast of the huge walled plain Mendeleev, about midway between the craters Schliemann to the northeast and Marconi to the southwest. It is about the same size as Albategnius on the near side.

text: Chaplygin is a large

text: lunar

text: impact crater

text: that lies on the

text: far side

text: of the

text: Moon

text: . It is located to the southeast of the huge walled plain

text: Mendeleev

text: , about midway between the craters

text: Schliemann

text: to the northeast and

text: Marconi

text: to the southwest. It is about the same size as

text: Albategnius

text: on the near side.

text: A partial solar eclipse occurred on November 2, 1910. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on November 2, 1910. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A total solar eclipse occurred on February 9, 1766. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on February 9, 1766. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Lunar distance is also called Earth-Moon distance, Earth–Moon characteristic distance, or distance to the Moon, and commonly indicated with LD or  \Delta_{\oplus L}. The mean semi-major axis has a value of . The time-averaged distance between Earth and Moon centers is . The actual distance varies over the course of the orbit of the Moon, from  at the perigee to  at apogee, resulting in a differential range of .

text: Lunar distance is also called Earth-Moon distance, Earth–Moon characteristic distance, or distance to the Moon, and commonly indicated with LD or  \Delta_{\oplus L}. The mean semi-major axis has a value of . The time-averaged distance between Earth and Moon centers is . The actual distance varies over the course of the

text: orbit of the Moon

text: , from  at the

text: perigee

text: to  at

text: apogee

text: , resulting in a differential range of .

text: The Moon possesses abundant raw materials that are potentially relevant to a hierarchy of future applications, beginning with the use of lunar materials to facilitate human activities on the Moon itself and progressing to the use of lunar resources to underpin a future industrial capability within the Earth-Moon system.

text: The Moon possesses abundant raw materials that are potentially relevant to a hierarchy of future applications, beginning with the use of lunar materials to facilitate human activities on the

text: Moon

text: itself and progressing to the use of lunar resources to underpin a future industrial capability within the Earth-Moon system.

text: Idel'son is a lunar crater that is located on the far side of the Moon. It lies just behind the southern lunar limb, in a region that is sometimes brought into view of the Earth due to libration. Idel'son is situated to the southwest of the huge walled plain Schrödinger.

text: Idel'son is a

text: lunar

text: crater

text: that is located on the

text: far side

text: of the

text: Moon

text: . It lies just behind the southern lunar limb, in a region that is sometimes brought into view of the

text: Earth

text: due to

text: libration

text: . Idel'son is situated to the southwest of the huge walled plain

text: Schrödinger

text: The term eclipse is most often used to describe either a solar eclipse, when the Moon's shadow crosses the Earth's surface, or a lunar eclipse, when the Moon moves into the Earth's shadow. However, it can also refer to such events beyond the Earth–Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its host planet, or a moon passing into the shadow of another moon. A binary star system can also produce eclipses if the plane of the orbit of its constituent stars intersects the observer's position.

text: The term eclipse is most often used to describe either a

text: solar eclipse

text: , when the Moon's shadow crosses the Earth's surface, or a

text: lunar eclipse

text: , when the Moon moves into the Earth's shadow. However, it can also refer to such events beyond the Earth–Moon system: for example, a planet moving into the shadow cast by one of its moons, a moon passing into the shadow cast by its host planet, or a moon passing into the shadow of another moon. A

text: binary star

text: system can also produce eclipses if the plane of the orbit of its constituent stars intersects the observer's position.

text: The Earth and the Sun sometimes meet in the lunar sky, causing an eclipse. On the Earth, one then sees a lunar eclipse, in which the Moon passes through the Earth's shadow, but on the Moon, one would see the Sun go behind the Earth—causing a solar eclipse. As the apparent diameter of the Earth is four times as large as that of the Sun, the Sun would be hidden behind the Earth for hours. The Earth's atmosphere would be visible as a reddish ring. An attempt was made to use the Apollo 15 Lunar rover TV camera to view such an eclipse, but the camera or its power source failed after the astronauts left for Earth.

text: The Earth and the Sun sometimes meet in the lunar sky, causing an

text: eclipse

text: . On the Earth, one then sees a

text: lunar eclipse

text: , in which the Moon passes through the Earth's shadow, but on the Moon, one would see the Sun go behind the Earth—causing a

text: solar eclipse

text: . As the apparent diameter of the Earth is four times as large as that of the Sun, the Sun would be hidden behind the Earth for hours. The

text: Earth's atmosphere

text: would be visible as a reddish ring. An attempt was made to use the

text: Apollo 15

text: Lunar rover

text: TV camera to view such an eclipse, but the camera or its power source failed after the astronauts left for Earth.

text: Webb was played by Dan Lauria in the 1998 miniseries, From the Earth to the Moon.

text: Webb was played by

text: Dan Lauria

text: in the 1998 miniseries,

text: From the Earth to the Moon

text: The first serious attempts at naming the features of the Earth's Moon as seen through a telescope were made by Michel Florent van Langren in 1645. His work is considered the first true map of the Moon, as it portrayed the various lunar maria, craters, and mountain peaks and ranges. Many of the features were given names that had a distinctly Catholic religious character, using the period names of Catholic royalty for craters and the names of Catholic saints for the capes and promontories. The maria were given Latin names of seas and oceans. Minor craters were given the names of astronomers, mathematicians, and other notable scholars of the past and present periods.

text: The first serious attempts at naming the features of the Earth's Moon as seen through a telescope were made by

text: Michel Florent van Langren

text: in 1645. His work is considered the first true map of the Moon, as it portrayed the various

text: lunar maria

text: crater

text: s, and mountain peaks and ranges. Many of the features were given names that had a distinctly

text: Catholic

text: religious character, using the period names of Catholic royalty for craters and the names of Catholic saints for the capes and promontories. The maria were given

text: Latin

text: names of seas and oceans. Minor craters were given the names of astronomers, mathematicians, and other notable scholars of the past and present periods.

text: At the Moon's surface, the beam is about  wide and scientists liken the task of aiming the beam to using a rifle to hit a moving dime  away. The reflected light is too weak to be seen with the human eye: out of 10 photons aimed at the  reflector, only one will be received back on Earth every few seconds, even under good conditions. They can be identified as originating from the laser because the laser is highly monochromatic. This is one of the most precise distance measurements ever made, and is equivalent in accuracy to determining the distance between Los Angeles and New York to . , work is progressing on increasing the accuracy of the Earth–Moon measurements to near millimeter accuracy, though the performance of the reflectors continues to degrade with age.

text: At the Moon's surface, the beam is about  wide and scientists liken the task of aiming the beam to using a rifle to hit a moving

text: dime

text: away. The reflected light is too weak to be seen with the human eye: out of 10 photons aimed at the  reflector, only one will be received back on Earth every few seconds, even under good conditions. They can be identified as originating from the laser because the laser is highly

text: monochromatic

text: . This is one of the most precise distance measurements ever made, and is equivalent in accuracy to determining the distance between Los Angeles and New York to . , work is progressing on increasing the accuracy of the Earth–Moon measurements to near millimeter accuracy, though the performance of the reflectors continues to degrade with age.

text: The Hollow Moon hypothesis, or Spaceship Moon hypothesis, proposes that Earth's Moon is either wholly hollow or otherwise contains a substantial interior space. No scientific evidence exists to support the idea; seismic observations and other data collected since spacecraft began to orbit or land on the Moon indicate that it has a thin crust, extensive mantle and small, dense core, although overall it is much less dense than Earth.

text: The Hollow Moon hypothesis, or Spaceship Moon hypothesis, proposes that Earth's

text: Moon

text: is either wholly hollow or otherwise contains a substantial interior space. No

text: scientific evidence

text: exists to support the idea; seismic observations and other data collected since spacecraft began to orbit or land on the Moon indicate that it has a thin crust, extensive mantle and small, dense core, although overall it is much less dense than Earth.

text: Though often classified as a conservative or even a neocon, Goldblatt has on occasion veered from right of center positions. He has been a steadfast supporter of the war against totalitarian Islam  and a fierce critic of hip hop culture, postmodernism and multiculturalism, but he has also argued in favor of legalizing of gay marriage  and upholding the Roe v. Wade decision and has written sympathetically about Barack Obama.

text: Though often classified as a

text: conservative

text: or even a

text: neocon

text: , Goldblatt has on occasion veered from right of center positions. He has been a steadfast supporter of the war against totalitarian Islam  and a fierce critic of

text: hip hop

text: culture,

text: postmodernism

text: and

text: multiculturalism

text: , but he has also argued in favor of legalizing of gay marriage  and upholding the Roe v. Wade decision and has written sympathetically about

text: Barack Obama

text: The Moon is however also "bestower, radiant, glorious, possessed of water, possessed of warmth, possessed of knowledge, wealth, riches, discernment, weal, verdure, good, and the healing one" (Dhalla, 1938:214; Yasht 7.5, Nyaish 3.7). "During the spring, the Moon causes plants to grow up out of the earth" (Yasht 7.4, Nyaish 3.6). In the litany to the Moon, she is described as the "queen of the night."

text: A partial solar eclipse will occur on January 14, 2029. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: will occur on January 14, 2029. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: A partial solar eclipse occurred on August 20, 1906. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on August 20, 1906. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: The fruiting bodies of this species are semicircular or shell-shaped, with dimensions of  broad by  long. The brackets are typically  thick, although it can be considerably thicker at the point of the broad attachment to the tree. Ryvarden and Gilbertson give maximum fruiting body dimensions of  wide by  long by  thick. The fruiting body margin is rounded, and sometimes wavy, felt-like or tomentose on the flattened upper surface, which is typically orange-brown to rusty-brown in color. The color of the lower pore-bearing surface is cinnamon-, rust-, or olivaceous-brown, and there are 5 to 6 pores per millimeter.

text: The fruiting bodies of this species are semicircular or shell-shaped, with dimensions of  broad by  long. The brackets are typically  thick, although it can be considerably thicker at the point of the broad attachment to the tree. Ryvarden and Gilbertson give maximum fruiting body dimensions of  wide by  long by  thick. The fruiting body margin is rounded, and sometimes wavy, felt-like or tomentose on the flattened upper surface, which is typically orange-brown to rusty-brown in color. The color of the lower pore-bearing surface is cinnamon-, rust-, or

text: olivaceous

text: -brown, and there are 5 to 6 pores per millimeter.

text: This is a list of maria (singular mare) on the Moon. Lunar Maria are the large, dark, regions of the moon. They do not actually contain any water, however they are believed to have been formed from molten rock from the moon's mantle coming out onto the surface of the moon. It also includes the one oceanus and the features known by the names lacus, palus and sinus. The modern system of lunar nomenclature was introduced in 1651 by Riccioli. Riccioli's map of the moon was drawn by Francesco Maria Grimaldi, who has a crater named after him.

text: This is a list of

text: maria

text: (singular mare) on the

text: Moon

text: . Lunar Maria are the large, dark, regions of the moon. They do not actually contain any water, however they are believed to have been formed from molten rock from the moon's mantle coming out onto the surface of the moon. It also includes the one oceanus and the features known by the names lacus, palus and sinus. The modern system of lunar nomenclature was introduced in 1651 by

text: Riccioli

text: Francesco Maria Grimaldi

text: , who has a crater named after him.

text: Frank's front-page World-Telegram expose' did much to popularize the story of "Red Spy Queen" Elizabeth Bentley; he appeared with her on one of the first episodes of Meet the Press. A former communist who had worked for The Daily Worker, Frank testified before Rep. Richard Nixon and HUAC to support Whittaker Chambers's accusations against Alger Hiss.

text: Frank's front-page

text: World-Telegram

text: expose' did much to popularize the story of "Red Spy Queen"

text: Elizabeth Bentley

text: ; he appeared with her on one of the first episodes of

text: Meet the Press

text: . A former communist who had worked for

text: The Daily Worker

text: , Frank testified before Rep.

text: Richard Nixon

text: and

text: HUAC

text: to support

text: Whittaker Chambers

text: 's accusations against

text: Alger Hiss

text: With the high visibility KMA operated on a slogan of "Keep Millions Advised."  KFNF was to operate on "Keep Friendly, Never Frown."

text: A total solar eclipse occurred on October 10, 1912. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on October 10, 1912. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Neison is a lunar crater that lies to the south of the crater Meton, in the northern part of the Moon. The high latitude of this crater means that the crater appears foreshortened when viewed from the Earth, having an elliptical appearance even though it is nearly circular in shape.

text: Neison is a

text: lunar

text: crater

text: that lies to the south of the crater

text: Meton

text: , in the northern part of the

text: Moon

text: . The high latitude of this crater means that the crater appears foreshortened when viewed from the

text: Earth

text: , having an

text: elliptical

text: appearance even though it is nearly circular in shape.

text: A total solar eclipse occurred on August 30, 1905. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: occurred on August 30, 1905. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: Immediately after arriving in Budapest, Milanković met the Director of the Library of the Hungarian Academy of Science, Koloman von Szilly who, as a mathematician, eagerly accepted Milanković and enabled him to work undisturbed in the Academy's library and the Central Meteorological Institute. Milanković spent four years in Budapest, almost the entire war. He used mathematical methods to study the current climate of inner planets of the solar system. In 1916 he published a paper entitled "Investigation of the climate of the planet Mars". Milanković calculated that the average temperature in the lower layers the atmosphere on Mars is  and the average surface temperature is . Also, he concluded that: "This large temperature difference between the ground and lower layers of the atmosphere is not unexpected. Great transparency for solar radiation makes that is the climate of Mars very similar to altitudes climate of our Earth." Today it is known that the average temperature is , but that the ground temperatures and air temperatures generally differ. In any case, Milanković theoretically proved that Mars has an extremely harsh climate. In addition to considering Mars, he dealt with the climatic conditions prevailing on Venus and Mercury. His calculations of the temperature conditions on the neighboring Moon are particularly significant. Milanković knew that one day on the Moon lasts 15 Earth days, and this is the amount and length of night. Milanković calculated that the surface temperature on the day side of the moon reaches +100.5 °C. Also, he calculated that the temperature during the early morning on the Moon, or before the rise of the Sun over horizon, was -58 °C. Today it is known that the surface temperature on the day side of the Moon reaches +108 °C and that it falls at night to -153 °C.

text: Immediately after arriving in Budapest, Milanković met the Director of the Library of the

text: Hungarian Academy of Science

text: Koloman von Szilly

text: who, as a mathematician, eagerly accepted Milanković and enabled him to work undisturbed in the Academy's library and the Central Meteorological Institute. Milanković spent four years in Budapest, almost the entire war. He used mathematical methods to study the current climate of inner planets of the solar system. In 1916 he published a paper entitled "Investigation of the climate of the planet Mars". Milanković calculated that the average temperature in the lower layers the atmosphere on

text: Mars

text: is  and the average surface temperature is . Also, he concluded that: "This large temperature difference between the ground and lower layers of the atmosphere is not unexpected. Great transparency for solar radiation makes that is the climate of Mars very similar to altitudes climate of our Earth." Today it is known that the average temperature is , but that the ground temperatures and air temperatures generally differ. In any case, Milanković theoretically proved that Mars has an extremely harsh climate. In addition to considering Mars, he dealt with the climatic conditions prevailing on

text: Venus

text: and

text: Mercury

text: . His calculations of the temperature conditions on the neighboring

text: Moon

text: are particularly significant. Milanković knew that

text: one day on the Moon

text: lasts 15 Earth days, and this is the amount and length of night. Milanković calculated that the surface temperature on the day side of the moon reaches +100.5 °C. Also, he calculated that the temperature during the early morning on the Moon, or before the rise of the Sun over horizon, was -58 °C. Today it is known that the surface temperature on the day side of the Moon reaches +108 °C and that it falls at night to -153 °C.

text: A total solar eclipse will occur on January 5, 2057. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide.

text: A total

text: solar eclipse

text: will occur on January 5, 2057. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: apparent diameter

text: The rest of the story is Sankarappillai's fall clashing with his own family.

text: This half-hour series was broadcast on Tuesdays at 5:00 p.m. from 27 September to 3 October 1953, then moved to a Wednesday 5:00 p.m. time slot from 21 October 1953 to 25 May 1954.

text: An earthrise that might be witnessed from the surface of the Moon would be quite unlike moonrises on Earth. Because the Moon is tidally locked with the Earth, one side of the Moon always faces toward Earth. Interpretation of this fact would lead one to believe that the Earth's position is fixed on the lunar sky and no earthrises can occur, however, the Moon librates slightly, which causes the Earth to draw a Lissajous figure on the sky. This figure fits inside a rectangle 15°48' wide and 13°20' high (in angular dimensions), while the angular diameter of the Earth as seen from Moon is only about 2°. This means that earthrises are visible near the edge of the Earth-observable surface of the Moon (about 20% of the surface). Since a full libration cycle takes about 27 days, earthrises are very slow, and it takes about 48 hours for Earth to clear its diameter. During the course of the month-long lunar orbit, an observer would additionally witness a succession of "Earth phases", much like the lunar phases seen from Earth. That is what accounts for the half-illuminated globe seen in the photograph.

text: An earthrise that might be witnessed from the surface of the Moon would be quite unlike moonrises on Earth. Because the Moon is

text: tidally locked

text: with the Earth,

text: one side of the Moon

text: always faces toward Earth. Interpretation of this fact would lead one to believe that the Earth's position is fixed on the lunar sky and no earthrises can occur, however, the Moon

text: librates

text: slightly, which causes the Earth to draw a

text: Lissajous figure

text: on the sky. This figure fits inside a rectangle 15°48' wide and 13°20' high (in angular dimensions), while the

text: angular diameter

text: of the Earth as seen from Moon is only about 2°. This means that earthrises are visible near the edge of the Earth-observable surface of the Moon (about 20% of the surface). Since a full libration cycle takes about 27 days, earthrises are very slow, and it takes about 48 hours for Earth to clear its diameter. During the course of the month-long

text: lunar orbit

text: , an observer would additionally witness a succession of "Earth phases", much like the

text: lunar phase

text: s seen from Earth. That is what accounts for the half-illuminated globe seen in the photograph.

text: A partial solar eclipse occurred on October 12, 1996. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.

text: A partial

text: solar eclipse

text: occurred on October 12, 1996. A

text: solar eclipse

text: occurs when the

text: Moon

text: passes between

text: Earth

text: and the

text: Sun

text: Water is the source of moon,

text: Water is the source of moon,

text: Hayseth Moon (The 37th generation Moon Knight)