Moon - Composition. More than 4.5 billion years ago, the surface of the Moon was a liquid magma ocean. Scientists think that one component of lunar rocks, KREEP (K-potassium, Rare Earth Elements, and P-phosphorus), represents the last chemical remnant of that magma ocean. KREEP is actually a composite of what scientists term "incompatible elements": those which cannot fit into a crystal structure and thus were left behind, floating to the surface of the magma. For researchers, KREEP is a convenient tracer, useful ...

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Moon, Moon - The two sides, Moon - Orbit, Moon - Earth & Moon, Moon - Origin and history, Moon - Physical characteristics, Moon - Composition, Moon - Selenography, Moon - Presence of water, Moon - Magnetic field, Moon - Atmosphere, Moon - Eclipses, Moon - Occultation of stars, Moon - Observation of the Moon, Moon - Exploration of the Moon, Moon - Human understanding of the Moon, Moon - Myth and folk culture, Moon - The Moon as muse, Moon - Astrology, Moon - Scientific understanding, Moon - Meteor impact on the Moon, Moon - Legal status, Moon - Satellites, Moon - Surface installations, Moon - Lunar location listings

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Moon, Moon - The two sides of the Moon, Moon - Orbit, Moon - Earth & Moon, Moon - Tidal Effects, Moon - Double-planet hypotheses, Moon - Origin and history, Moon - Physical characteristics, Moon - Composition, Moon - Selenography, Moon - Presence of water, Moon - Magnetic field, Moon - Atmosphere, Moon - Eclipses, Moon - Occultation of stars, Moon - Observation of the Moon, Moon - Exploration of the Moon, Moon - Human understanding of the Moon, Moon - Myth and folk culture, Moon - The Moon as muse, Moon - Astrology, Moon - Scientific understanding, Moon - Meteor impact on the Moon, Moon - Legal status, Moon - Satellites, Moon - Surface installations, Moon - Lunar location listings

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So far the only close-up images of Umbriel are from the Voyager 2 probe, which made observations of the moon during its Uranus flyby in January, 1986. During the flyby the southern hemisphere of the moon was pointed towards the Sun so only it was studied. Umbriel's surface is the darkest of the Uranian moons, and it is also the least geologically active. It is mostly composed of water ice, with the balance made up of silicate rock an ...

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Umbriel moon, Umbriel moon - Name, Umbriel moon - Physical characteristics

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The Moon as seen from Earth Ammonia Carbon dioxide The Moon is the planet Earth's only natural satellite. It has no formal name other than "The Moon", although in English it is occasionally called Luna (Latin for moon), or Selene, to distinguish it from the generic "moon" (natural satellites of other planets are also called moons). Its symbol is a crescent (Unicode: ☾). The terms lunar, selene/seleno-, and cynthion (from the Lunar deities Selene and Cynthia) refer to the Moon (apo ...

Including:

Moon - The two sides Moon - Orbit Moon - Earth & Moon Moon - Origin and history Moon - Physical characteristics
Moon - Composition Moon - Selenography Moon - Presence of water Moon - Magnetic field Moon - Atmosphere
Moon - Eclipses Moon - Occultation of stars Moon - Observation of the Moon Moon - Exploration of the Moon Moon - Human understanding of the Moon
Moon - Myth and folk culture Moon - The Moon as muse Moon - Astrology Moon - Scientific understanding Moon - Meteor impact on the Moon
Moon - Legal status Moon - Satellites Moon - Surface installations
Moon - Lunar location listings

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Hyperion moon - Shape. Hyperion is one of the largest highly irregular (non-spherical) bodies in the solar system (second to Proteus). A possible explanation for this is that Hyperion is a fragment of a larger body that was broken by a large impact in the distant past. The largest crater on Hyperion is approximately 120 km in diameter and 10 km deep. Hyperion moon - Composition. Like most of Saturn's moons, Hyperion's low density indicates that it is composed largely of water i ...

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Hyperion moon, Hyperion moon - Name, Hyperion moon - Physical characteristics, Hyperion moon - Shape, Hyperion moon - Composition, Hyperion moon - Surface features, Hyperion moon - Rotation

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Phoebe is roughly spherical and has a diameter of 220 kilometres (about 137 miles), which is equal to about one-fifteenth of the diameter of Earth's moon. Phoebe rotates on its axis every nine hours and it completes a full orbit around Saturn in about 18 months. Its surface temperature is only 75 K (-198°C). Most of Saturn's inner moons have very bright surfaces, but Phoebe's albedo is very low (0.06), as dark as lamp black. The Phoebean surface is extremely heavily scarred, with craters up to 80 kilom ...

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Phoebe moon, Phoebe moon - Name, Phoebe moon - Orbital characteristics, Phoebe moon - Physical characteristics, Phoebe moon - Spacecraft flybys

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Enceladus moon - Interior. Relatively little is known about the interior of Enceladus. However, some insights were gained during the recent flybys of Enceladus by the Cassini Spacecraft. Based on the effects of Enceladus' gravity on the Cassini Spacecraft during those flybys, the Cassini Navigation team determined that it has a mass of 1.08×1020 kg which, combined with its known size, yields a mean density of 1.61 g/cm3 (Turtle et al. 2005). This density is higher than ...

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Enceladus moon, Enceladus moon - Name, Enceladus moon - Physical characteristics, Enceladus moon - Interior, Enceladus moon - Surface, Enceladus moon - Named surface features, Enceladus moon - Exploration of Enceladus

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Mimas' low density (1.17) indicates that it is composed mostly of water ice with only a small amount of rock. Due to the tidal forces acting on it, the moon is not perfectly spherical; its longest axis is about 10% longer than the shortest. The somewhat ovoid shape of Mimas is especially noticeable in recent images from the Cassini probe. Mimas' most distinctive feature is a colossal impact crater 130 km across, named Herschel after the moon's discoverer. Herschel's diameter is almost a third of the moon's own diameter; its wal ...

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Mimas moon, Mimas moon - Name, Mimas moon - Physical characteristics, Mimas moon - Mimas in fiction and film

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Umbriel (um'-bree-ul) is a moon of Uranus discovered on 1851-10-24 by William Lassell. It was discovered at the same time as Ariel. Umbriel moon - Name. The name "Umbriel" and the names of all four satellites of Uranus then known were suggested by John Herschel in 1852 at the request of Lassell ([2]). Lassell had earlier endorsed Herschel's 1847 naming scheme for the seven then-known satellites of Saturn and had named his newly-discovered eighth satellite Hyperion in accordance with Herschel's naming ...

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Umbriel moon - Name Umbriel moon - Physical characteristics

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Amalthea (IPA: /ˌæməlˈθiə/, am'-ul-thee'-a, Greek Αμάλθεια) is the third moon of Jupiter (in order of distance from the planet), and the fifth in order of discovery, hence its Roman numeral designation of Jupiter V. It was discovered on September 9, 1892 by Edward Emerson Barnard using the 36 inch (91 cm) refractor telescope at Lick Observatory. Amalthea was the last moon to be discovered by direct visual observation (as opposed to photograph ...

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Amalthea moon - Physical characteristics Amalthea moon - The view from the surface Amalthea moon - Amalthea in fiction

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The low density of Iapetus indicates that it is primarily composed of ice, with only a small amount of rocky materials. Furthermore, the overall shape of Iapetus is neither spherical nor ellipsoid—unusual for a large moon; parts of its globe appear to be squashed flat, and its unique equatorial ridge (see below) is so high that it visibly distorts the moon's shape even when viewed from a distance. Scientists are currently unable to describe Iapetus's shape perfectly as the Cas ...

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Iapetus moon, Iapetus moon - Name, Iapetus moon - Orbit, Iapetus moon - Physical characteristics, Iapetus moon - Two-tone coloration, Iapetus moon - The equatorial ridge, Iapetus moon - Speculation that Iapetus is artificial, Iapetus moon - Iapetus in fiction

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Ariel (air'-ee-ul, pronounced [ˈɛəɹiəl]) is a moon of Uranus discovered on 1851-10-24 by William Lassell. It was discovered at the same time as Umbriel. Ariel moon - Name. Ariel is named after the leading sylph in Alexander Pope's poem Rape of the Lock. The name "Ariel" and the names of all four satellites of Uranus then known were suggested by John Herschel in 1852 at the request of Lassell ([1]). Lassell had earlier endorsed H ...

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Ariel moon - Name Ariel moon - Physical characteristics

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Callisto (IPA: /kəˈlɪstoʊ/, ka-lis'-toe, Greek Καλλιστώ) is a moon of the planet Jupiter, discovered in 1610 by Galileo Galilei. It is the third-largest moon in the solar system, about the same size as the planet Mercury. Callisto moon - Name. Callisto is named after Callisto, one of Zeus's many love interests in Greek mythology. Although the name "Callisto" was suggested by Simon Marius soon after the moon's discovery, t ...

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Callisto moon - Name Callisto moon - Physical characteristics Callisto moon - Callisto in fiction

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87 Sylvia (sil'-vee-a) is one of the largest main belt asteroids. It orbits beyond most of the main belt asteroids, so it is classed as one of the Cybeles (see Minor planet groups). Sylvia is remarkable for being the first known asteroid to possess more than one moon. 87 Sylvia - Discovery and naming. Sylvia was discovered by N. R. Pogson on May 16, 1866 from Madras (Chennai), India. Paul Herget, in his The Names of the Minor Planets (1955), attributes the name as honouring the first wife of a ...

Including:

87 Sylvia - Discovery and naming 87 Sylvia - Physical characteristics 87 Sylvia - Moons

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243 Ida is a Main belt asteroid that was imaged by the Galileo probe on August 28, 1993. It was the first binary asteroid to be discovered. 243 Ida - Discovery and name. Ida was discovered by Johann Palisa on September 29, 1884 in Vienna. It is named after Ida, a Cretan nymph in Greek mythology who lived on a mountain that bore her name (see Mount Ida, Crete). 243 Ida - Moon. Ida has a small moon, Dactyl, which was discovered by Galileo mission member Ann Harch, wh ...

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243 Ida - Discovery and name 243 Ida - Moon 243 Ida - Physical characteristics
243 Ida - Ida 243 Ida - Dactyl

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Pluto is the ninth planet in the solar system. Discovered in 1930 and immediately classified as a planet, its status is currently under dispute. Pluto has an eccentric orbit that is highly inclined in respect to the other planets and takes it inside the orbit of Neptune. Its largest moon is Charon, discovered in 1978; two smaller moons were discovered in 2005. Pluto's astronomical symbol is a P-L monogram, ♇. This represents both the first two letters of the name Pluto and the initials of Percival Lowell ...

Including:

Pluto - Discovery and naming Pluto - Orbit Pluto - Physical characteristics
Pluto - Mass and size Pluto - Atmosphere Pluto - Appearance
Pluto - Pluto's moons
Pluto - Charon Pluto - The outer moons
Pluto - Exploration of Pluto Pluto - The Pluto debate
Pluto - Planet X? Pluto - Minor planet? Pluto - New discoveries
Pluto - Pluto in popular culture

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Click image for description Venus, the second planet from the Sun, is named after the Roman goddess Venus. A terrestrial planet, it is sometimes called Earth's "sister planet", as the two are very similar in size and bulk composition. Although all planets' orbits are elliptical, Venus's orbit is the closest to circular, with an eccentricity of less than 1%. As Venus is closer to the Sun than the Earth, it always appears in roughly the same direction from Earth as the Sun (the greatest e ...

Including:

Venus - Physical characteristics
Venus - Atmosphere Venus - Surface features Venus - Venus' moon Venus - Aspects
Venus - Observations and explorations of Venus
Venus - Lowest distances to earth
Venus - Cultural references

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Amalthea is the reddest object in the solar system, even redder than the planet Mars. The reddish color is apparently due to sulfur originating from Io. Bright patches of green appear on the major slopes of Amalthea, but the nature of this color is currently unknown. Amalthea is irregularly shaped, with dimensions of 270 × 168 × 150 km; the long axis is oriented toward Jupiter. It is also heavily scarred by craters, some of which are extremely large relative to the size of the moon. Pan, the largest crater, measures 100 kilometers a ...

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Amalthea moon, Amalthea moon - Physical characteristics, Amalthea moon - The view from the surface, Amalthea moon - Amalthea in fiction

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So far the only close-up images of Titania are from the Voyager 2 probe, which photographed the moon during its Uranus flyby in January, 1986. At the time of the flyby the southern hemisphere of the moon was pointed towards the Sun so only it was studied. Titania is composed of roughly 50% water ice, 30% silicate rock, and 20% methane-related organic compounds. A major surface feature is a huge canyon that dwarfs the scale of the Grand Canyon on Earth and is in the same class as the Valles Ma ...

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Titania moon, Titania moon - Name, Titania moon - Physical characteristics, Titania moon - Occultation, Titania moon - Titania in fiction

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Tethys is an icy body similar in nature to Dione and Rhea. The density of Tethys is 1.21 g/cm3, indicating that it is composed almost entirely of water-ice. The Tethyan surface is heavily cratered and contains numerous cracks caused by faults in the ice. There are two different types of terrain found on Tethys, one composed of densely cratered regions and the other consisting of a dark colored and lightly cratered belt that extends across the moon. The light cratering of this second region indicates that Tethys was once int ...

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Tethys moon, Tethys moon - Name, Tethys moon - Physical characteristics, Tethys moon - Tethys in fiction

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