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 closest major moon, Titan. It has also the most inclined orbital plane of the regular satellites; only the irregular outer satellites like Phoebe have more inclined orbits. The cause of this is unknown. Because of this distant, inclined orbit, Iapetus is the only large moon from which the rings of Saturn would be clearly visible; from the other inner moons, the rings ...

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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

Read more here: » Iapetus moon: Encyclopedia II - Iapetus moon - Orbit

See also:

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

Read more here: » 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 its angular diameter, or by about 0.5°. The Moon differs from most satellites of other planets in that its orbit is close to the plane of the ecliptic and not in the Earth's equatorial plane. Several ways to consider a complete orbit are detailed in the table below, but the two most familiar are: the sidereal month being the time it takes to make a complete orbit with respect to the stars, about 27.3 ...

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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

Read more here: » Moon: Encyclopedia II - Moon - Orbit

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

Read more here: » Moon: Encyclopedia - Moon

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 opposite to the planet's rotation). The small outer moons of Jupiter and Saturn also have retrograde orbits, as do three of Uranus' outer moons, but the largest of them (Phoebe) has only 8% of the diameter (and 0.03% of the mass) of Triton. Moons in retrograde orbits cannot form out of the same region of the solar nebula as the planets they orbit, but must be captured from elsewhere; it is thought that Triton ...

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Triton moon, Triton moon - Name, Triton moon - Orbit, Triton moon - Physical characteristics, Triton moon - Seasons, Triton moon - Planetary geology, Triton moon - General Topography, Triton moon - “Cantaloupe terrain”, Triton moon - History of observation and exploration, Triton moon - Potential for life

Read more here: » Triton moon: Encyclopedia II - Triton moon - Orbit

JIMO was to have a large number of revolutionary features. Throughout its main voyage to the Jupiter moons, it was to be propelled by an ion propulsion called HiPEP, and powered by a small fission reactor. A Brayton power conversion system would convert reactor heat into electricity. Providing a thousand times the electrical output of conventional solar or RTG based power system, the reactor was expected to open up opportunities like flying a full scale ice-penetrating rada ...

See also:

Jupiter Icy Moons Orbiter, Jupiter Icy Moons Orbiter - The JIMO spacecraft, Jupiter Icy Moons Orbiter - Preliminary design specifications

Read more here: » Jupiter Icy Moons Orbiter: Encyclopedia II - Jupiter Icy Moons Orbiter - The JIMO spacecraft

For more than 100 years, Phoebe was Saturn's outermost known moon, until the discovery of several smaller moons in 2000. Phoebe is almost 4 times more distant from Saturn than its nearest major neighbor (Iapetus), and is substantially larger than any of the other moons orbiting planets at comparable distances. All of Saturn's moons up to Iapetus orbit very nearly in the plane of Saturn's equator. The outer moons can be broken down into two groups: Siarnaq's group (Kiviuq, Ijiraq, Paaliaq, Albiorix, Erriapo, Siarnaq and Tarvos) is incl ...

See also:

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

Read more here: » Phoebe moon: Encyclopedia II - Phoebe moon - Orbital characteristics

Janus occupies essentially the same orbit as the moon Epimetheus. This caused some confusion for astronomers, who assumed that there was only one body in that orbit, and for a long time struggled to figure out what was going on. It was eventually realised that they were trying to reconcile observations of two distinct objects as a single object. The discovery of Janus is attributed to its first observer: Audouin Dollfus, on December 15, 1966 (IAUC 1987). The new object was given the temporary designation S/1966 S 2. Previously, ...

See also:

Janus moon, Janus moon - Discovery and orbit, Janus moon - Name, Janus moon - Orbital relationship between Epimetheus and Janus, Janus moon - Physical characteristics

Read more here: » Janus moon: Encyclopedia II - Janus moon - Discovery and orbit

2003 UB313 (center) and moon (right of center). Keck Observatory. 2003 UB313 is a trans-Neptunian object (TNO) which California astronomers at Mount Palomar observatory describe as "definitely bigger" than the planet Pluto. The object has already been dubbed the tenth planet by the discoverers, NASA, and some media outlets, but it is not yet clear whether it will be widely accepted as a new planet or not. It has at least one moon. No official name for ...

Including:

2003 UB313 - Discovery 2003 UB313 - Classification 2003 UB313 - Name 2003 UB313 - Orbit 2003 UB313 - Size 2003 UB313 - Surface 2003 UB313 - Moon

Read more here: » 2003 UB313: Encyclopedia - 2003 UB313

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

Read more here: » Pluto: Encyclopedia - Pluto

Phobos orbits Mars below the synchronous orbit radius, meaning that it moves around Mars faster than Mars itself rotates. Therefore it rises in the west, moves comparatively rapidly across the sky (in 4 h 15 min or less) and sets in the east, approximately twice a day (every 11 h 6 min). It is so close to the surface (in a low-inclination equatorial orbit) that it cannot be seen above the horizon from latitudes greater than 70.4°. This low orbit means that Phobos will eventually be destroyed: tidal forces are lowering its orbit, curr ...

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Phobos moon, Phobos moon - Discovery, Phobos moon - Orbital characteristics, Phobos moon - Physical characteristics, Phobos moon - Origin, Phobos moon - Hollow Phobos claims, Phobos moon - Jonathan Swift's 'prediction', Phobos moon - Phobos in fiction

Read more here: » Phobos moon: Encyclopedia II - Phobos moon - Orbital characteristics

Apollo 8 was the second manned mission of the Apollo space program, in which Commander Frank Borman, Command Module Pilot James Lovell and Lunar Module Pilot William Anders became the first humans to leave Earth orbit and to orbit around the Moon. It was also the first manned launch of the Saturn V rocket. NASA prepared for the mission in only four months. The hardware involved had only been used a few times—the Saturn V had launched only twice before, and the Apollo spacecraft had only just finished its first manned m ...

Including:

Apollo 8 - Planning Apollo 8 - The Saturn V Apollo 8 - The mission
Apollo 8 - Launch and trans-lunar injection Apollo 8 - Coasting to the Moon Apollo 8 - Lunar sphere of influence Apollo 8 - Lunar orbit Apollo 8 - Unplanned manual re-alignment Apollo 8 - Cruise back to Earth and re-entry
Apollo 8 - Historical importance Apollo 8 - Crew
Apollo 8 - Backup crew Apollo 8 - Support crew
Apollo 8 - Mission parameters
Apollo 8 - Earth parking orbit Apollo 8 - Lunar orbit Apollo 8 - Translunar injection burn

Read more here: » Apollo 8: Encyclopedia - Apollo 8

2003 EL61 (also written 2003 EL61), nicknamed "Santa" (non-official designation), is a very large and unusual Kuiper belt object recently discovered by Mike Brown et al. at Caltech in the United States. The nickname stems from its discovery just after Christmas, on December 28, 2004, although the Caltech team had acquired images of it starting May 6, 2004. The nickname is only temporary and will not be the official name of the object. IAU guidelines dictate that the object will be named after a c ...

Including:

2003 EL61 - Discovery controversy 2003 EL61 - Size and composition 2003 EL61 - Orbit 2003 EL61 - Moons
2003 EL61 - S/2005 2003 EL61 1 2003 EL61 - S/2005 2003 EL61 2

Read more here: » 2003 EL61: Encyclopedia - 2003 EL61

An orbital node is one of the two points where an inclined orbit crosses a plane of reference (e.g. the equator for geocentric orbits, the ecliptic for heliocentric orbits). Nodes do not exist for orbits with inclination equal to zero (equatorial orbits or ecliptic orbits). The ascending (or north) node is where the object moves north from the southern hemisphere to the northern, the descending (or south) node is where the object moves back south. The line of nodes is the intersection of the object's orbital plane with the plane of reference, a ...

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Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. The spacecraft consists of two main elements: the Cassini orbiter, named after the Italian-French astronomer Giovanni Domenico Cassini, and the Huygens probe, named after the Dutch astronomer Christiaan Huygens. It was launched on October 15, 1997 and entered Saturn's orbit on July 1, 2004. On December 25, 2004 the probe separated from the orbiter at approximately 02:00 UTC, with deployment confirmed by th ...

Including:

Cassini-Huygens - Overview Cassini-Huygens - History Cassini-Huygens - Spacecraft design
Cassini-Huygens - Instrumentation Cassini-Huygens - Plutonium power source and controversy
Cassini-Huygens - The Huygens probe Cassini-Huygens - Important events and discoveries
Cassini-Huygens - Timeline Cassini-Huygens - Jupiter flyby Cassini-Huygens - Test of Einstein's theory of general relativity Cassini-Huygens - Spoke phenomenon verified Cassini-Huygens - New moons of Saturn Cassini-Huygens - Phoebe flyby Cassini-Huygens - Saturn rotation Cassini-Huygens - Orbiting Saturn Cassini-Huygens - Titan flybys Cassini-Huygens - Huygens encounter with Titan Cassini-Huygens - Enceladus flybys Cassini-Huygens - Radio Occultations of Saturn's Rings
Cassini-Huygens - Trajectory Cassini-Huygens - Notes Cassini-Huygens - Books and print references

Read more here: » Cassini-Huygens: Encyclopedia - Cassini-Huygens

Janus and Epimetheus are "co-orbital". Janus' orbital radius from Saturn is currently 151,472 km and Epimetheus' orbital radius is 151,422 km, a separation of only 50 km. Since closer orbits have higher velocities the two moons must inevitably approach each other, and since Epimetheus' diameter is 115 km and Janus' is 178 km it would seem at first glance that a collision is also inevitable. But as the inner moon catches up with the outer moon their mutual gravitational attraction boosts the inner moon's momentum and raises its orbit, causing ...

See also:

Janus moon, Janus moon - Discovery and orbit, Janus moon - Name, Janus moon - Orbital relationship between Epimetheus and Janus, Janus moon - Physical characteristics

Read more here: » Janus moon: Encyclopedia II - Janus 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 km, a separation of only 50 km. Since closer orbits have higher velocities, the two moons must inevitably approach each other, and since Epimetheus' diameter is 115 km and Janus' is 178 km it would seem at first glance that a collision were inevitable. But as the inner moon catches up with the outer moon their gravitational attraction boosts the inner moon's momentum and raises its orbit, while the o ...

See also:

Epimetheus moon, Epimetheus moon - Discovery, Epimetheus moon - Orbital relationship between Epimetheus and Janus, Epimetheus moon - Physical characteristics

Read more here: » Epimetheus moon: Encyclopedia II - Epimetheus moon - Orbital relationship between Epimetheus and Janus

Epimetheus occupies essentially the same orbit as the moon Janus. Astronomers assumed that there was only one body in that orbit, and accordingly had a hard time figuring out their orbital characteristics; it is obviously impossible to reconcile the observations of two distinct objects as a single object. Audouin Dollfus observed a moon on December 15, 1966, which he proposed to be named "Janus"[3]. On December 18, Richard L. Walker made a similar observation which is now credited as the discovery of Epimetheus[4]. However, at the time, it was believed that there was only one moon, unoff ...

See also:

Epimetheus moon, Epimetheus moon - Discovery, Epimetheus moon - Orbital relationship between Epimetheus and Janus, Epimetheus moon - Physical characteristics

Read more here: » Epimetheus moon: Encyclopedia II - Epimetheus moon - Discovery

Janus is named after Janus, the two-faced Roman god. Although the name was informally proposed soon after the initial 1966 discovery, it was not officially given this name until 1983. Epimetheus received its name at the same time. According to the OED, the adjectival form of the moon's name is Janian. ...

See also:

Janus moon, Janus moon - Discovery and orbit, Janus moon - Name, Janus moon - Orbital relationship between Epimetheus and Janus, Janus moon - Physical characteristics

Read more here: » Janus moon: Encyclopedia II - Janus moon - Name

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 ...

See also:

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

Read more here: » Phoebe moon: Encyclopedia II - Phoebe moon - Physical characteristics