Encyclopedia - Moon: Encyclopedia Ii - Moon - Physical Characteristics
Moon - Composition. More than 4.5 billion years ago, the surface of the Moon was a liquid magma ocean. Scientists think that one compon...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Physical Characteristics
Moon - Composition. More than 4.5 billion years ago, the surface of the Moon was a liquid magma ocean. Scientists think that one compon...   » Read the article

Encyclopedia - Umbriel Moon: Encyclopedia Ii - Umbriel Moon - Physical Characteristics
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 J...   » Read the article

Encyclopedia - Moon: Encyclopedia - Moon
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 tha...   » Read the article

Encyclopedia - Hyperion Moon: Encyclopedia Ii - Hyperion Moon - Physical Characteristics
Hyperion moon - Shape. Hyperion is one of the largest highly irregular (non-spherical) bodies in the solar system (second to Proteus). ...   » Read the article

Encyclopedia - Phoebe Moon: Encyclopedia Ii - Phoebe Moon - Physical Characteristics
Phoebe is roughly spherical and has a diameter of 220 kilometres (about 137 miles), which is equal to about one-fifteenth of the diameter...   » Read the article

Encyclopedia - Enceladus Moon: Encyclopedia Ii - Enceladus Moon - Physical Characteristics
Enceladus moon - Interior. Relatively little is known about the interior of Enceladus. However, some insights were gained during the re...   » Read the article

Encyclopedia - Mimas Moon: Encyclopedia Ii - Mimas Moon - Physical Characteristics
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 act...   » Read the article

Encyclopedia - Umbriel Moon: Encyclopedia - Umbriel Moon
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. Umbri...   » Read the article

Encyclopedia - Amalthea Moon: Encyclopedia - Amalthea Moon
Amalthea (IPA: /ˌæməlˈθiə/, am'-ul-thee'-a, Greek Αμάλθεια) is the third moon of Jupiter (in order of distance from the pla...   » Read the article

Encyclopedia - Iapetus Moon: Encyclopedia Ii - Iapetus Moon - Physical Characteristics
The low density of Iapetus indicates that it is primarily composed of ice, with only a small amount of rocky materials. Furthermore, the ...   » Read the article

Encyclopedia - Ariel Moon: Encyclopedia - Ariel Moon
Ariel (air'-ee-ul, pronounced [ˈɛəɹiəl]) is a moon of Uranus discovered on 1851-10-24 by William Lassell. It was discovered at the s...   » Read the article

Encyclopedia - Callisto Moon: Encyclopedia - Callisto Moon
Callisto (IPA: /kəˈlɪstoʊ/, ka-lis'-toe, Greek Καλλιστώ) is a moon of the planet Jupiter, discovered in 1610 by Galileo Galil...   » Read the article

Encyclopedia - 87 Sylvia: Encyclopedia - 87 Sylvia
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 o...   » Read the article

Encyclopedia - 243 Ida: Encyclopedia - 243 Ida
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 discovere...   » Read the article

Encyclopedia - Pluto: Encyclopedia - Pluto
Pluto is the ninth planet in the solar system. Discovered in 1930 and immediately classified as a planet, its status is currently under d...   » Read the article

Encyclopedia - Venus: Encyclopedia - Venus
Click image for description Venus, the second planet from the Sun, is named after the Roman goddess Venus. A terrestrial planet, it is so...   » Read the article

Encyclopedia - Amalthea Moon: Encyclopedia Ii - Amalthea Moon - Physical Characteristics
Amalthea is the reddest object in the solar system, even redder than the planet Mars. The reddish color is apparently due to sulfur origi...   » Read the article

Encyclopedia - Titania Moon: Encyclopedia Ii - Titania Moon - Physical Characteristics
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, ...   » Read the article

Encyclopedia - Tethys Moon: Encyclopedia Ii - Tethys Moon - Physical Characteristics
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 ent...   » Read the article

Encyclopedia - Miranda Moon: Encyclopedia Ii - Miranda Moon - Physical Characteristics
Miranda's surface may be mostly water ice, with the low density body being made of silicate rock and methane-related organic compounds. M...   » Read the article

Encyclopedia - Epimetheus Moon: Encyclopedia Ii - Epimetheus Moon - Physical Characteristics
There are several Epimethean craters larger than 30 km in diameter, as well as both large and small ridges and grooves. The extensive cra...   » Read the article

Encyclopedia - Io Moon: Encyclopedia Ii - Io Moon - Physical Characteristics
Unlike most moons in the outer solar system, Io may be somewhat similar in bulk composition to the terrestrial planets, primarily compose...   » Read the article

Encyclopedia - Phobos Moon: Encyclopedia Ii - Phobos Moon - Physical Characteristics
Phobos is a dark body that appears to be composed of C-type surface materials. It is similar to the C-type (blackish carbonaceous chondri...   » Read the article

Encyclopedia - Ariel Moon: Encyclopedia Ii - Ariel Moon - Physical Characteristics
The first and so far only close-up observations of Ariel were made by the Voyager 2 probe during its January 1986 Uranus fly-by. Because ...   » Read the article

Encyclopedia - Titan Moon: Encyclopedia Ii - Titan Moon - Physical Characteristics
Titan is larger than the planet Mercury[6] (though less massive) and is the second largest natural satellite in the solar system after Ga...   » Read the article

Encyclopedia - Ganymede Moon: Encyclopedia Ii - Ganymede Moon - Physical Characteristics
Ganymede is composed of silicate rock and water ice, with an ice crust floating over a warmer ice mantle that may contain a layer of liqu...   » Read the article

Encyclopedia - Dione Moon: Encyclopedia Ii - Dione Moon - Physical Characteristics
Dione is composed primarily of water ice, but as the densest of Saturn's moons (aside from Titan, whose density is increased by gravitati...   » Read the article

Encyclopedia - Callisto Moon: Encyclopedia Ii - Callisto Moon - Physical Characteristics
Callisto is one of the most heavily cratered satellite in the solar system. In fact, impact craters and associated concentric rings are a...   » Read the article

Encyclopedia - Enceladus Moon: Encyclopedia Ii - Enceladus Moon - Named Surface Features
Scientists officially recognise the following geological features on Enceladus: Craters Fossae (ditches) Planitia (plains) Sulci (long p...   » Read the article

Encyclopedia - Phoebe Moon: Encyclopedia Ii - Phoebe Moon - Orbital Characteristics
For more than 100 years, Phoebe was Saturn's outermost known moon, until the discovery of several smaller moons in 2000. Phoebe is almost...   » Read the article

Encyclopedia - Phoebe Moon: Encyclopedia Ii - Phoebe Moon - Name
The moon is named after Phoebe, a Titan in Greek mythology. It is also designated Saturn IX. The IAU nomenclature standards have stated t...   » Read the article

Encyclopedia - Phoebe Moon: Encyclopedia Ii - Phoebe Moon - Spacecraft Flybys
The Voyager 2 spacecraft passed by Phoebe in September 1981, although the 2.2 Gm (2.2 million kilometres) distance and low resolution mea...   » Read the article

Encyclopedia - Rhea Moon: Encyclopedia Ii - Rhea Moon - Name
Rhea is named after the titan Rhea of Greek mythology. It is also designated Saturn V. Cassini named the four moons he discovered (T...   » Read the article

Encyclopedia - Enceladus Moon: Encyclopedia Ii - Enceladus Moon - Name
Enceladus is named after the mythological Enceladus. It is also designated Saturn II. The name "Enceladus" and the names of all seven sat...   » Read the article

Encyclopedia - Hyperion Moon: Encyclopedia Ii - Hyperion Moon - Name
The moon is named after Hyperion, a Titan in Greek mythology. It is also designated Saturn VII. Hyperion's discovery came shortly af...   » Read the article

Encyclopedia - Iapetus Moon: Encyclopedia Ii - Iapetus Moon - Orbit
The orbit of Iapetus is somewhat unusual. Although it is one of Saturn's largest moons, it orbits much farther from Saturn than the next ...   » Read the article

Encyclopedia - Tethys Moon: Encyclopedia Ii - Tethys Moon - Name
Tethys is named after the titan Tethys of Greek mythology. It is also designated Saturn III. Cassini named the four moons he discove...   » Read the article

Encyclopedia - Phobos Moon: Encyclopedia Ii - Phobos Moon - Phobos In Fiction
The first episode of the computer and video game Doom takes place in a UAC base on Phobos. Phobos also featured in Kim Stanley Robinson's...   » Read the article

Encyclopedia - Iapetus Moon: Encyclopedia Ii - Iapetus Moon - Speculation That Iapetus Is Artificial
The oddness of Iapetus has occasionally led to speculation that it may be an artificial construction by extraterrestrials. In 1980, Donal...   » Read the article

Encyclopedia - Mimas Moon: Encyclopedia Ii - Mimas Moon - Name
The name "Mimas" and the names of all seven satellites of Saturn then known were suggested by Herschel's son John Herschel in his 1847 pu...   » Read the article

Encyclopedia - Amalthea Moon: Encyclopedia Ii - Amalthea Moon - The View From The Surface
Jupiter would be an astonishing sight in Amalthea's night sky: 46 degrees across, it would appear roughly 92 times larger than than the f...   » Read the article

Encyclopedia - Iapetus Moon: Encyclopedia Ii - Iapetus Moon - Name
Iapetus is named after the mythological Iapetus. It is also designated Saturn VIII. Giovanni Cassini named the four moons he discovered (...   » Read the article

Encyclopedia - Epimetheus Moon: Encyclopedia Ii - Epimetheus Moon - Discovery
Epimetheus occupies essentially the same orbit as the moon Janus. Astronomers assumed that there was only one body in that orbit, and acc...   » Read the article

Encyclopedia - Epimetheus Moon: Encyclopedia Ii - Epimetheus Moon - Orbital Relationship Between Epimetheus And Janus
Epimetheus and Janus are co-orbital: Janus' orbital radius from Saturn is currently 151,472 km and Epimetheus' orbital radius is 151,422 ...   » Read the article

Encyclopedia - Phobos Moon: Encyclopedia Ii - Phobos Moon - Discovery
Phobos was discovered by American astronomer Asaph Hall on August 18, 1877 at the US Naval Observatory in Washington, D.C at about 09:14 ...   » Read the article

Encyclopedia - Titania Moon: Encyclopedia Ii - Titania Moon - Name
The name "Titania" and the names of all four satellites of Uranus then known were suggested by Herschel's son John Herschel in 1852 at th...   » Read the article

Encyclopedia - Phobos Moon: Encyclopedia Ii - Phobos Moon - Hollow Phobos Claims
Around 1958, the distinguished Russian astrophysicist Iosif Samuilovich Shklovsky, studying the secular acceleration of Phobos' orbital m...   » Read the article

Encyclopedia - Triton Moon: Encyclopedia Ii - Triton Moon - Potential For Life
Like the atmosphere of Titan, Triton's atmosphere is composed of nitrogen and methane. Nitrogen is also the principal constituent of Eart...   » Read the article

Encyclopedia - Janus Moon: Encyclopedia Ii - Janus Moon - Orbital Relationship Between Epimetheus And Janus
Janus and Epimetheus are "co-orbital". Janus' orbital radius from Saturn is currently 151,472 km and Epimetheus' orbital radius is 151,42...   » Read the article

Encyclopedia - Janus Moon: Encyclopedia Ii - Janus Moon - Name
Janus is named after Janus, the two-faced Roman god. Although the name was informally proposed soon after the initial 1966 discovery, it ...   » Read the article

Encyclopedia - Triton Moon: Encyclopedia Ii - Triton Moon - Orbit
Triton is unique among all large moons in the solar system for its retrograde orbit around the planet (i.e., it orbits in a direction opp...   » Read the article

Encyclopedia - Triton Moon: Encyclopedia Ii - Triton Moon - Planetary Geology
Triton has a similar size, density, and chemical composition to that of Pluto, and upon verifying the eccentric orbit of Pluto that cross...   » Read the article

Encyclopedia - Ariel Moon: Encyclopedia Ii - 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 o...   » Read the article

Encyclopedia - Triton Moon: Encyclopedia Ii - Triton Moon - Name
Triton is named after Triton (from the Greek Τρίτων,son of Poseidon. The name was proposed by Camille Flammarion in 1880. It is per...   » Read the article

Encyclopedia - Io Moon: Encyclopedia Ii - Io Moon - Volcanism
Io is most noteworthy for its volcanic nature; it is the most volcanically active body in the Solar System. Similarly to volcanoes on Ear...   » Read the article

Encyclopedia - Triton Moon: Encyclopedia Ii - Triton Moon - History Of Observation And Exploration
In 1820, William Lassell started to make mirrors for his telescope and in 1844, made better mirrors that allowed him to discover the plan...   » Read the article

Encyclopedia - Phobos Moon: Encyclopedia Ii - Phobos Moon - Orbital Characteristics
Phobos orbits Mars below the synchronous orbit radius, meaning that it moves around Mars faster than Mars itself rotates. Therefore it ri...   » Read the article

Encyclopedia - Triton Moon: Encyclopedia Ii - Triton Moon - Seasons
The axis of rotation of Triton is highly irregular inclined 157 degrees in relation to the axis of Neptune, and 130 degrees in respect to...   » Read the article

Encyclopedia - Janus Moon: Encyclopedia Ii - Janus Moon - Discovery And Orbit
Janus occupies essentially the same orbit as the moon Epimetheus. This caused some confusion for astronomers, who assumed that there was ...   » Read the article

Encyclopedia - Europa Moon: Encyclopedia Ii - Europa Moon - Surface
The Europan surface is relatively smooth; few features more than a few hundred metres high have been observed, but topographic relief in ...   » Read the article

Encyclopedia - Europa Moon: Encyclopedia Ii - Europa Moon - Exploration Of Europa
Most of our knowledge of Europa comes from the flybys by the Voyager and Galileo missions. Various proposals have been made for future mi...   » Read the article

Encyclopedia - Titan Moon: Encyclopedia Ii - Titan Moon - Name
Huygens named his discovery simply Saturni Luna (Latin for "Saturn's moon", which can also be written Luna Saturni) (De Saturni Luna obse...   » Read the article

Encyclopedia - Titan Moon: Encyclopedia Ii - Titan Moon - Titan In Fiction
Titan is one of the most popular settings in science fiction other than Earth's Moon and the planets. Titan moon - Titan in literature. ...   » Read the article

Encyclopedia - Dione Moon: Encyclopedia Ii - Dione Moon - Name
Cassini named the four moons he discovered (Tethys, Dione, Rhea and Iapetus) Lodicea Sidera ("the stars of Louis") to honour king Louis X...   » Read the article

Encyclopedia - Callisto Moon: Encyclopedia Ii - 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 Sim...   » Read the article

Encyclopedia - 243 Ida: Encyclopedia Ii - 243 Ida - Moon
Ida has a small moon, Dactyl, which was discovered by Galileo mission member Ann Harch, while examining the delayed image downloads, disc...   » Read the article

Encyclopedia - Pluto: Encyclopedia Ii - Pluto - Pluto's Moons
Pluto has three known natural satellites: Charon, first identified in 1978, and two smaller, as yet unnamed moons discovered in 2005. Pl...   » Read the article

Encyclopedia - Pluto: Encyclopedia Ii - Pluto - Exploration Of Pluto
Little is known about Pluto because of its great distance from Earth and because no exploratory spacecraft have visited Pluto yet. The Vo...   » Read the article

Encyclopedia - Pluto: Encyclopedia Ii - Pluto - Physical Characteristics
More than 75 years after its discovery, many facts about Pluto remain unknown, mainly due to the fact that it is the only planet that has...   » Read the article

Encyclopedia - Pluto: Encyclopedia Ii - Pluto - Discovery And Naming
Pluto was discovered by the astronomer Clyde Tombaugh at the Lowell Observatory in Arizona on February 18, 1930 after an extensive search...   » Read the article

Encyclopedia - Pluto: Encyclopedia Ii - Pluto - Orbit
Pluto's orbit is unlike those of the other planets. It is highly inclined above the plane of the ecliptic, and highly eccentric (non-circ...   » Read the article

Encyclopedia - Pluto: Encyclopedia Ii - Pluto - The Pluto Debate
Pluto - Planet X?. The planet Pluto was originally discovered in 1930 in the course of a search for a body sufficiently massive to acco...   » Read the article

Encyclopedia - Jupiter: Encyclopedia Ii - Jupiter - Natural Satellites
Jupiter has at least 63 moons. For a complete listing of these moons, please see Jupiter's natural satellites. For a timeline of their di...   » Read the article

Encyclopedia - Jupiter: Encyclopedia Ii - Jupiter - Natural Satellites
Jupiter has at least 63 moons. For a complete listing of these moons, please see Jupiter's natural satellites. For a timeline of their di...   » Read the article

Encyclopedia - Venus: Encyclopedia Ii - Venus - Observations And Explorations Of Venus
Venus has been observed several times within the past 4000 years by a number of people, including the Greeks. Venus - Lowest distances t...   » Read the article

Encyclopedia - Venus: Encyclopedia Ii - Venus - Observations And Explorations Of Venus
Venus sky movement patterns have been observed several times within the past 4000 years by a number of people, including the Greeks. For ...   » Read the article

Encyclopedia - Venus: Encyclopedia Ii - Venus - Physical Characteristics
Venus - Atmosphere. Venus has an atmosphere consisting mainly of carbon dioxide and a small amount of nitrogen, with a pressure at the ...   » Read the article

Encyclopedia - Jupiter: Encyclopedia Ii - Jupiter - Exploration Of Jupiter
A number of probes have visited Jupiter. Jupiter - Pioneer flyby missions. Pioneer 10 flew past Jupiter in December of 1973, followed b...   » Read the article

Encyclopedia - Venus: Encyclopedia Ii - Venus - Orbital Characteristics
Venus - Orbit. Although all planets' orbits are elliptical, Venus's orbit is the closest to circular, with an eccentricity of less than...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Orbit
The Moon makes a complete orbit about the Earth approximately once every 28 days. Each hour the Moon moves relative to the stars by an am...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Orbit
The Moon makes a complete orbit about once every 28 days. Each hour the Moon moves relative to the stars by an amount roughly equal to it...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Human Understanding Of The Moon
Moon - Myth and folk culture. Main article: Moon (mythology) Moon - The Moon as muse. Main article: Moon in art and literature Th...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Occultation Of Stars
During the year, the Moon occults - or passes over and hides for a period of time - stars and planets. Because the Moon is close to Earth...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Earth & Moon
Moon - Tidal Effects. The tides on Earth are generated by the Moon's gravitation (see tide and tidal force for a more detailed discussi...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Exploration Of The Moon
The first leap in Lunar observation was caused by the invention of the telescope. Especially Galileo Galilei made good use of this new in...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - The Two Sides Of The Moon
The far side is sometimes called the "dark side". In this case "dark" means "unknown and hidden" and not "lacking light" as implied by th...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Observation Of The Moon
During the brightest full moons, the Moon can have an apparent magnitude of about −12.6. For comparison, the Sun has an apparent magnit...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Human Understanding Of The Moon
Moon - Myth and folk culture. Moon - The Moon as muse. The Moon has been the subject of many works of art and literature and the insp...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Occultation Of Stars
During the year, the moon occults sometimes stars and planets. Because the moon is close to the earth, occultations of stars are not vis...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Legal Status
Though several flags of the Soviet Union and the United States have been symbolically planted on the moon, the Russian and U.S. governmen...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Earth & Moon
The tides on Earth are generated by the Moon's gravitation (see tide and tidal force for a more detailed discussion). There are two tidal...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Origin And History
The inclination of the Moon's orbit makes it implausible that the Moon formed along with the Earth or was captured later; its origin is t...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Exploration Of The Moon
The first leap in Lunar observation was caused by the invention of the telescope. Especially Galileo Galilei made good use of this new in...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - The Two Sides
The far side is sometimes called the "dark side". In this case "dark" means "unknown and hidden" and not "lacking light" as implied by th...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Eclipses
The angular diameters of the Moon and the Sun as seen from Earth overlap in their variation, so that both total and annular solar eclipse...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Observation Of The Moon
During the brightest full moons, the Moon can have an apparent magnitude of about −12.6. For comparison, the Sun has an apparent magnit...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Legal Status
Though several flags of the Soviet Union and the United States have been symbolically planted on the moon, the Russian and U.S. governmen...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Origin And History
The inclination of the Moon's orbit makes it implausible that the Moon formed along with the Earth or was captured later; its origin is t...   » Read the article

Encyclopedia - Moon: Encyclopedia Ii - Moon - Eclipses
The angular diameters of the Moon and the Sun as seen from Earth overlap in their variation, so that both total and annular solar eclipse...   » Read the article