Space Today Online - Moons of the Solar System SPACE TODAY ONLINE ~~ COVERING SPACE FROM EARTH TO THE EDGE OF THE UNIVERSE Moons of the Solar System Massive planet Jupiter below the moon Io click NASA image to enlarge A moon is a natural satellite rotating around a planet. While moons vary in size, each moon is much smaller than its planet. Almost 140 moons are known in the Solar System. Several moons are larger than the planet Pluto and two moons are larger than the planet Mercury. There also are many small moons that may be asteroids captured by their planets. Only Mercury and Venus do not have any moons. By comparison, Earth has one moon and Mars has two. Jupiter has the most of any planet. Saturn is second. Pictures taken by the Hubble Space Telescope suggest there may be even more moons around those outer planets. earth's moon » Largest. The largest moon is Ganymede with a diameter of 3,280 miles, even larger than either of the planets Mercury and Pluto. Saturn's moon Titan is the second largest in the Solar System with a diameter of 3,200 miles, half again as large as Earth's Moon.

The Planets and Their Moons PLANET Jupiter 62 Io, Europa, Ganymede, Callisto, Amalthea, Himalia, Elara, Pasiphae, Sinope, Lysithea, Carme, Ananke, Leda, Metis, Adrastea, Thebe, Callirrhoe, Themisto, Kalyke, Iocaste, Erinome, Harpalyke, Isonoe, Praxidike, Megaclite, Taygete, Chaldene, Autonoe, Thyone, Hermippe, Eurydome, Sponde, Pasithee, Euanthe, Kale, Orthosie, Euporie, Aitne, plus others yet to receive names Saturn 33 Titan, Rhea, Iapetus, Dione, Tethys, Enceladus, Mimas, Hyperion, Prometheus, Pandora, Phoebe, Janus, Epimetheus, Helene, Telesto, Calypso, Atlas, Pan, Ymir, Paaliaq, Siarnaq, Tarvos, Kiviuq, Ijiraq, Thrym, Skadi, Mundilfari,

 Erriapo, Albiorix, Suttung, plus others yet to receive names Uranus 27 Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Puck, Miranda, Ariel, Umbriel, Titania, Oberon, Caliban, Sycorax, Prospero, Setebos, Stephano, Trinculo, plus others yet to receive names Neptune Triton, Nereid, Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, plus others yet to receive names Pluto 139 Saturn.

When the Cassini spacecraft from Earth arrived at Saturn in 2004, it promptly found two previously unseen moons. They turned out to be the smallest bodies seen until then around the ringed planet. The tiny natural satellites are about 2 miles and 2.5 miles in diameter. That's smaller than the city of Boulder, Colorado. Previously, the smallest moons seen around Saturn were are about 12 miles across. The moons are 120,000 miles and 131,000 miles from the center of planet Saturn between the moons Mimas and Enceladus. The newly discovered bodies were labeled S/2004 S1 and S/2004 S2. Later, they will be given names. The NASA JPL team wondered if S/2004 S1 might not be an object called S/1981 S14 that had turned up in a 1981 Voyager image. Saturn moons » Smallest.

The smallest moon is Deimos, at Mars, only seven miles in diameter, although its size now is rivaled by the small shepherd moons discovered by Cassini at Saturn and by others yet to be counted and named in the rings around Jupiter, Saturn and other giant gas planets in the outer Solar System. There may be tiny moons as small as only around a mile across. Pluto. Charon is the moon closest in size to its planet, Pluto. Earth's Moon is second in that comparison. Neptune. The interplanetary probe Voyager 2 in 1989 found six previously-unknown moons orbiting Neptune. They ranged in diameter from 33 miles to 250 miles. In 1991, they were named Naiad, Thalassa, Despina, Galatea, Larissa, Proteus. The names Galatea and Larissa were controversial since asteroids previously had been given those names. Names are assigned by the nomenclature committee of the International Astronomical Union (IAU). Triton. Before Voyager 2, astronomers knew Neptune had two moons, Triton and Nereid.

With a surface temperature of –391 degrees, Triton was found by Voyager 2 to have a thin veneer of methane and nitrogen on top of water ice on its surface. Triton had been thought to have a diameter of 2,361 miles, close in size to Earth's Moon, but turned out to be smaller, around 1,690 miles. Nereid is 210 miles in diameter. Pan. A new moon only 12 miles in diameter was discovered in 1990 circling the planet Saturn. It was Saturn's 18th and most distant moon. Photos of the planet, moons and rings, left over from the 1981 Saturn flyby by Voyager 2, had been filed away at NASA's Ames Research Center in Mountain View, California, for a decade. A planetary scientist was tipped off to Pan's presence by a disturbance in a 200-mi.-wide gap — Encke's Gap — in Saturn's outermost A ring. Pan's gravity moved particles in the large A ring, creating a gap with waves along the edges like the wake of a motorboat.

Checking the wavy edges, he calculated the probable position and mass of the moon and compared them with Voyager 2 positions and camera angles in 1980-81. When finally uncovered, the moon stood out as a small bright spot in 11 pictures among 30,000 photos scanned by a computer. In 1991, the moon officially was named Pan. It was the second time since Neptune was discovered in 1894 that a gravity disturbance had been used to pinpoint a previously-unknown Solar System body. Inner Solar System. The inner Solar System includes the planets Mercury, Venus, Earth and Mars. Of all the known moons in our Solar System, only three are in the inner region. Mars has two. Earth has one. Mercury and Venus are the only planets without moons. The outer Solar System includes Jupiter, Saturn, Uranus, Neptune and Pluto and the rest of the moons. More moons are discovered each year in the outer Solar System by astronomers using ever more powerful equipment. Atmospheres. Most moons are airless, but Jupiter's Io, Saturn's Titan and Neptune's Triton seem to have atmospheres. Titan may be flooded with an ocean of liquid ethane.

Triton may be covered by an ocean of liquid nitrogen. Io seems to have a thin sulphur dioxide atmosphere from volcanos. Titan. Titan appears to have an organic chemistry in its atmosphere which may resemble the primitive Earth before the dawn of life. It is the only moon known to have a thick, organic-rich nitrogen atmosphere. Surface temperature is around –290 degrees Fahrenheit. Solar System's moons are listed below: Exploring the Moons of the Outer Solar System The moons of the outer planets are popular targets with planners of future spaceflights. Jupiter has more moons than any other planet. Its best known moons are the four large planet-sized bodies Io, Europa, Ganymede and Callisto. jupiter » Callisto is the outermost of the four and the most heavily cratered body in the Solar System. It may have a vast water ocean indside. Io is innermost of the four. This sulfurous moon is the most volcanic world in our Solar System. It is peppered with hundreds of volcanoes, several of which might be active at any given moment. Europa has an icy surface that may hide a layer of warm slush or even liquid water.

That would make it one of the few places in the Solar System with that life-sustaining liquid. Ganymede is the largest moon of Jupiter and the largest moon in the Solar System. In fact, Ganymede is larger in diameter than the planet Mercury and much larger than the planet Pluto. Ganymede has its own magnetic field. Saturn has some unique moons. Here are some examples: Titan is Saturn's largest moon. Mimas has an enormous crater – probably a hole caused by a meteorite. Enceladus has a very bright surface. It may have active water volcanoes. Tethys has a canyon running three-quarters of the way around its surface. That means it may once have been split almost in half. Dione and Rhea have wispy white markings on one side. Hyperion is oddly shaped and the length of its day is constantly changing. Iapetus is half bright and half dark. Pan, by comparison, is a very tiny moon. Its diameter is only 20 km, which on the sale above would be only half the size of a BB. Uranus' moons are eye-openers. They have statuesque mountains towering more than ten miles high. Incredibly deep valleys.

Vast plains, some with a mysterious dark surface. Moon diameters range from a bit fatter than 25 miles up to about 1,100 miles. Moons Moons: Moons are `fossils" into a planet's past.

The major, named moon systems are: Earth: Luna (The Moon) Mars: Deimos, Phobos Jupiter: Adrastea, Amalthea, Ananke, Callisto, Carme, Elara, Europa, Ganymede, Himalia, Io, Leda, Lysithea, Metis, Pasiphae, Sinope, Thebe Saturn: Atlas, Calypso, Dione, Enceladus, Epimetheus, Helene, Hyperion, Iapetus, Janus, Mimas, Pan, Pandora, Phoebe, Prometheus, Rhea, Telesto, Tethys, Titan Uranus: Ariel, Belinda, Bianca, Cordelia, Cressida, Desdemona, Juliet, Miranda, Oberon, Ophelia, Portia, Puck, Rosalind, Titania, Umbriel Neptune: Despina, Galatea, Larissa, Naiad, Nereid, Proteus, Thalassa, Triton Pluto: Charon (note: Pluto/Charon form a binary system, but Charon is the smaller so it is classed as the moon of Pluto) New, smaller moons are being discovered all the

 time with recent space missions.

The total count of moons (as of 12/18/2001) are: Mercury - 0 moons Mars - 2 moons Uranus - 20 moons Venus - 0 moons Jupiter - 28 moons Neptune - 8 moons Earth - 1 moon Saturn - 30 moons Pluto - 1 moon Moons range in shape from highly irregular to spheres. Their shape reflects their formation history, irregular objects are ill-formed moons (captured asteroids or comets) or pieces of a larger moon, spherical objects were once molten spheres, probably at the time of their formation. Moons of Mars: Deimos & Phobos We speculate, from their irregular appearances and low mean densities, that Deimos and Phobos, are captured asteroids. Both Deimos and Phobos are saturated with craters. Deimos has a smoother appearance caused by partial filling of some of its craters. Moons of Jupiter: Jupiter has 63 confirmed moons as of Jan 2009, i.e. moons with known orbits around Jupiter. Eight of these moons are regular, meaning they have prograde, nearly circular orbits.

They are composed of the four Galilean satellites, plus the inner or Amalthea group: Adrastea is a typical small moon Metis is the innermost known satellite of Jupiter Amalthea is one of Jupiter's smaller, irregular moons, an example of moon collecting dust from another moon (Io) The remaining 55 moons are irregular, they have a mixture of prograde and retrograde orbits with high inclinations and eccentricities. Jupiter's regular satellites are believed to have formed from a circumplanetary disk, a ring of accreting gas and solid debris analogous to a protoplanetary disk. The irregular satellites are substantially smaller objects with more distant and eccentric orbits. They form families with shared similarities in orbit (semi-major axis, inclination, eccentricity) and composition; it is believed that these are at least partially collisional families that were created when larger (but still small) parent bodies were shattered by impacts from asteroids captured by Jupiter's gravitational field. Moons of Saturn: The moons of Saturn are numerous and diverse, ranging from tiny moonlets less than 1 kilometer across to the enormous Titan, which is larger than the planet Mercury.

Saturn has sixty-two moons with confirmed orbits, fifty-three of which have names, and only thirteen of which have diameters larger than 50 kilometers. Saturn has seven moons that are large enough to become spherical. Twenty-four of Saturn's moons are regular satellites; they have prograde orbits not greatly inclined to the Saturn's equatorial plane. These include the seven major satellites, four small moons which exist in a Trojan orbit with larger moons, two mutually co-orbital moons and two moons which act as shepherds of Saturn's F Ring. Two other known regular satellites orbit within gaps in Saturn's rings. The relatively large Hyperion is locked in a resonance with Titan. The remaining regular moons orbit near the outer edge of the A Ring, within G Ring and between the major moons Mimas and Enceladus. The regular satellites are traditionally named after Titans and Titanesses or other figures associated with the mythological Saturn. The remaining thirty-eight, all small except one, are irregular satellites, whose orbits are much farther from Saturn, have high inclinations, and are mixed between prograde and retrograde. These moons are probably captured minor planets, or debris from the breakup of such bodies after they were captured, creating collisional families.

The irregular satellites have been classified by their orbital characteristics into the Inuit, Norse, and Gallic groups, and their names are chosen from the corresponding mythologies. The largest of the irregular moons is Phoebe, the ninth moon of Saturn, discovered at the end of the 19th century. The rings of Saturn are made up of objects ranging in size from microscopic to hundreds of meters, each of which is on its own orbit about the planet. Thus, a precise number of Saturnian moons cannot be given, as there is no objective boundary between the countless small anonymous objects that form Saturn's ring system and the larger objects that have been named as moons. At least 150 moonlets embedded in the rings have been detected by the disturbance they create in the surrounding ring material, though this is thought to be only a small sample of the total population of such objects. Daphnis drifts through the Keeler gap Atlas the second of Saturn's known satellites, orbits near the outer edge of the A-ring Enceladus is one of the innermost moons of Saturn.

Enceladus reflects almost 100 percent of the sunlight that strikes it and has evidence of internal heating and recent resurfacing effects Hyperion is one of the smaller moons of Saturn. It has a pock-marked body and is the largest irregularly shaped satellite ever observed.

Iapetus is one of the stranger moons of Saturn, its leading side is dark with a slight reddish color while its trailing side is bright Dione is the densest moon of Saturn other than Titan, and has several usual characteristics: 1) has a rocky core and ice crust, 2) is heavy cratering on trailing hemisphere, 3) has bright, wispy features Rhea is the largest airless satellite of Saturn that has different regions with different crater sizes indicating that parts of the moon have undergone resurfacing since formation Mimas is one of the innermost moons of Saturn with a very large impact crater that came close to fracturing the moon Tethys is an icy body similar in nature to Dione and Rhea Phoebe is the last of the known satellites of Saturn and orbits in a retrograde direction (opposite to the direction of the other satellites' orbits) in a plane much closer to the ecliptic than to Saturn's equatorial plane. Thus, Phoebe may be a captured asteroid with a composition unmodified since the time it was formed in the outer Solar System.

Moons of Uranus: Uranus, the seventh planet of the Solar System, has 27 known moons, all of which are named after characters from the works of William Shakespeare and Alexander Pope. William Herschel discovered the first two moons, Titania and Oberon, in 1787, and the other spherical moons were discovered in 1851 by William Lassell (Ariel and Umbriel) and in 1948 by Gerard Kuiper (Miranda). The remaining moons were discovered after 1985, either during the Voyager 2 flyby mission or with the aid of advanced Earth-based telescopes. A montage of Uranus' large moons and one smaller moon: from left to right Puck, Miranda, Ariel, Umbriel, Titania and Oberon. Uranian moons are divided into three groups: thirteen inner moons, five major moons, and nine irregular moons. The inner moons are small dark bodies that share common properties and origins with the planet's rings. The five major moons are massive enough to have achieved hydrostatic equilibrium (they were once molten spheres), and four of them show signs of internally driven processes such as canyon formation and volcanism on their surfaces.

The largest of these five, Titania, is 1,578 km in diameter and the eighth-largest moon in the Solar System, and about 20 times less massive than Earth's Moon. Uranus's irregular moons have elliptical and strongly inclined (mostly retrograde) orbits at great distances from the planet. Ariel is a relatively small satellite and is the brightest moon of Uranus Miranda with a jumbled surface unlike anything in the Solar System, indicates evidence of violent past with possible multiple shattering and reassembly Titania is the largest moon of Uranus and is marked by a few large impact basins Moons of Neptune: Neptune has thirteen known moons, by far the largest of which is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself. Over a century passed before the discovery of the second natural satellite, called Nereid. Neptune's moons are named for minor water deities in Greek mythology. Unique among all large planetary moons, Triton is an irregular satellite, as its orbit is retrograde to Neptune's rotation and inclined relative to the planet's equator.

The next-largest irregular satellite in the Solar System, Saturn's moon Phoebe, is only 0.03% Triton's mass. Triton is massive enough to have achieved hydrostatic equilibrium and to retain a thin atmosphere capable of forming clouds and hazes. Both its atmosphere and its surface are composed mainly of nitrogen with small amounts of methane and carbon monoxide. Triton's surface appears relatively young, and was probably modified by internally driven processes within the last few million years. The temperature at its surface is about 38K. Inward of Triton are six regular satellites, all of which have prograde orbits in planes that lie close to Neptune's equatorial plane. Some of these orbit among Neptune's rings. The largest of them is Proteus. Neptune also has six outer irregular satellites, including Nereid, whose orbits are much farther from Neptune, have high inclinations, and are mixed between prograde and retrograde. The two outermost ones, Psamathe and Neso, have the largest orbits of any natural satellites discovered in the Solar System to date.

Proteus is one of the darkest objects in the Solar System The Jovian Planets A Concise Guide to the Universe The Outer Jovian Planets Jupiter A. Jupiter is named after the Roman king of the gods. It is more than twice as massive as all the other planets in the solar system combined. B. Jupiter is a giant ball of hydrogen-based gasses, whose density is only slightly greater than water. Its surface features many alternating bands of clouds that spin in opposite directions. White bands are known as zones, dark bands are known as belts. They are caused by material rising from, and failing to, the interior of the planet. The risings and failings are due to convection currents within the planet. The Coriolis effect on the surface causes the winds to spin in opposite directions. Organic chemicals cause the color of the belts. C. The Great Red Spot on Jupiter is caused by winds spinning in opposite directions on the surface - essentially a permanent hurricane. D. Jupiter has no surface per se. As one descends through the clouds, they become increasingly dense. At a certain point, they are so dense, they are essentially liquid. E.

Jupiter gives off twice as much energy as it receives from the sun. This energy is probably residual heat from the formation of the planet. F. Jupiter has 16 named moons. The four largest can be seen easily from Earth, and are known as the Galilean satellites. Io is particularly interesting, as it is extremely volcanically active. The enormous gravitational field of Jupiter pulls and distorts Io to such an extent that internal friction heats up the moon. The internal heat manifests itself in volcanic activity, which produces sulfur, making the surface of the moon look reddish-orange. Europa, the next moon out, contains an icy crust covering a mantle of liquid water. Some planetary scientists think that Europa might be able to harbor life. Its surface has recently been found to be covered with a great deal of Epsom salts. Ganymede, the next moon, is the largest moon in the solar system, and is in fact larger than the planet Mercury. Callisto, the last Galilean moon, is similar in composition to Ganymede, but not quite as large. The moons of Jupiter formed in such a way as to mimic the formation of the solar system.

The small rocky moons formed towards the interior of the planetary nebula and the larger, lighter moons formed further out. G. Jupiter, as well as all of the Jovian planets, has rings. However, its rings are not as large or as visible as those of Saturn. The rings were not discovered until spacecraft were able to image the planet from behind so as to see the rings in relief. H. Jupiter exhibits differential rotation, in which the equator of the planet spins faster than the north and south poles. Only a planet made essentially out of gas could do this. All of the Jovian planets exhibit this feature. SATURN A. Saturn is named after the Roman god of the harvest. It is known for its complex ring system, as well as for its moon, Titan. Saturn is almost as large as Jupiter, but has less than one-third the mass. In a large enough ocean, Saturn would float, as it has an average density of less than one. B. Saturn lacks the striking banded cloud patterns of Jupiter. The reason is that it is just too cold. Saturn is nearly twice as far away from the sun as Jupiter. The exterior of Saturn is made up of frozen ammonia clouds.

The interior is otherwise similar to Jupiter's. C. Saturn has a large and complex system of rings. They may be from several different sources. First, the rings lie at about 2.44 the planetary radii of Saturn. At that distance, it as been calculated that any moon made of similar substance to the planet will be pulled apart by the gravitational attraction of the planet. This distance is known as the Roche Limit. Any satellite within this limit will be pulled apart. Additionally, the planet may have captured satellites, and broken them apart. There is a large gap in the rings of Saturn called the Cassini Division. The gaps in the rings are most probably due to shepherding satellites that orbit in resonance with the rings. The rings are made of myriad individual particles of rock and ice. They are 50,000 miles across and 200 yards deep. D. Saturn has 22 moons, the most interesting of which is Titan. Titan is one of two moons in the solar system with its own atmosphere. Some planetary scientists believe that Titan is one of the most likely places in the solar system for life to be found. URANUS A.

Uranus is named after the Roman god of' the sky. Uranus was discovered in 1781 by Sir William Herschel by careful observation of the heavens. He saw an object in his telescope which was disk-shaped and too large to be a star. After several months it became apparent to astronomers that this was a planet because it moved against the background stars but didn't grow a tail like a comet did. B. Uranus is a relatively featureless, pale blue planet. It lacks the cloud bands that are distinctive on the surface of Saturn and Jupiter. Part of the reason for this is it has a rotation about its axis that is almost in the plane of its orbit. In other words, whereas most planets, including Earth, spin almost directly up and down with respect to their orbital path, Uranus has been pushed over on its side and is spinning with its north or south pole occasionally pointing directly at the sun. This rotational pattern keeps Uranus from having a dynamic weather pattern. Half of the planet has almost constant heating for half the year, whereas most planets have the entire planet covered with partial heating over very short periods of rotation.

This odd rotation was probably caused by the impact of a large object early in the formation of the planet. C. Most of the moons of Uranus are named for characters in Shakespearean plays. There are moons named after Juliet and Puck, as well as other famous characters. Two of the moons are named after characters in Pope's Rape of the Lock, Umbrial and Belinda. NEPTUNE A. Neptune is named after the Roman god of the sea. The two largest moons of Neptune are Triton and Nereid. Triton is the Roman name for mermen, and Nereid the name for mermaids, thus keeping with the oceanic theme. Neptune was discovered simultaneously by English and French astronomers. B. Neptune is approximately the same size and composition of Uranus, but has a radically different atmosphere. Because it spins vertically on its axis, rather than on its side, it has a more dynamic surface, with the fastest winds in the solar system at well over a thousand miles per hour. C. Neptune was once seen to have a large blue spot, discovered by the Viking Space Probe, much like the Great Red Spot on Jupiter. However, recent pictures from the Hubble Space Telescope show that this spot has disappeared.

D. Neptune's moon, Triton, joins Saturn's moon, Titan, as the only other moon in the solar system with its own atmosphere. It is the largest of Neptune's many moons. PLUTO A. Pluto, named after the Roman god of the underworld, is not a Jovian Planet. American astronomer Clyde Tombaugh discovered the planet in 1930. Pluto's large moon is named after Charon, the ferryman over Styx, the river of the dead. Charon is very large compared to Pluto, and in fact it could be said that Pluto and Charon orbit one another, rather than Charon orbiting Pluto. Charon was not discovered until 1977. B. Not much is known about Pluto because of its small size and vast distance from the sun. It is presumed to be made of mostly frozen gasses and water, similar to most comets, and is thus probably a remnant left over from the formation of the solar system. In addition, because Pluto is very cold, the water on it would have a consistency similar to that of steel on Earth. C.

Pluto has a very elliptical orbit, which is inclined to the plane of orbit of the other planets by approximately 17 degrees. This trajectory takes it well away from the path of the other planets. Because of its highly elliptical orbit, Pluto is occasionally closer to the sun than Neptune. Moons of Neptune – Names & Composition of Neptunes Moons – PlanetFacts.org The Moon Moons of Neptune There are 13 moons discovered to orbit around the 8th planet of the solar system, Neptune. The first, and the largest, moon, Triton, to be discovered was found just 17 days after the planet itself was discovered. After Triton’s discovery, it took another century for astronomers to find the second moon of Neptune. The moons of Neptune are classified as Regular Moons and Irregular Moons. Regular moons are closer to the planet, some even closer than Neptune’s planetary rings. Irregular moons orbit farther from Neptune. The regular moons consist of Despina, Galatea, Larissa, Naiad, Proteus and Thalassa. Naiad and Thalassa are the two regular moons closest to the planet and orbits between two of Neptune’s planetary rings.

Despina is believed by astronomers to be a shepherd moon; small moons that orbit just outside the edge of planetary rings. Galatea is the fourth moon closest to Neptune and has a surface that displays no geological changes. It is believed that Galatea is a piece of one of Neptune’s ancient satellites. Galatea has been discovered to slowly move towards the surface of Neptune, which indicates that it will either crash with Neptune, or break up into planetary rings. Larissa and Proteus are the two largest of Neptune’s regular moons. Larissa has an estimated diameter of 200 km while Proteus is estimated to be around 150-250 km. The irregular moons of Neptune consist of Halimede, Laomedia, Nereid, Neso, Psamanthe, Sao and Triton. Triton is the largest moon with a 2,700 km diameter and is larger than the dwarf planets of the solar system Pluto and Eris. It has such a great mass that it accounts for 99.5% of the mass to orbit Neptune, moons and rings combined. Scientists believe that there may be liquid water inside Triton’s surface that they refer to as “ocean”.

Moons of Neptune i didnt know neptune had moons ice cream man Neptune is my favorite planet after earth ☺ love bug thanks abunch this helped me so much on my space project although i have to say that i found different information on different web sources so it didnt help with some planets,asteroids,and comets i knew it had 13 moons it helped also ;D This has helped us heaps in science 😀 Thankyoooooou planet facts people oh no you didnt!!!!!JB the moons of neptune are not THAT stupid!!! 🙂 i mean if it didnt have moons …….ah i got nothin 🙂 JB The moons on neptune is Stupid Jackson Driever Triton ("TRY ton") is the seventh and by far the largest of Neptune 's satellites: orbit : 354,760 km from Neptune diameter : 2700 km mass : 2.14e22 kg Discovered by Lassell in 1846 only a few weeks after the discovery of Neptune itself. In Greek mythology, Triton is a god of the sea, the son of Poseidon (Neptune); usually portrayed as having the head and trunk of a man and the tail of a fish.

Triton has been visited by only one spacecraft, Voyager 2 on Aug 25 1989. Almost everything we know about it comes from this encounter. Triton's orbit is retrograde . It is the only large moon to orbit "backwards", the only other moons with retrograde orbits are Jupiter 's moons Ananke , Carme , Pasiphae and Sinope and Saturn 's Phoebe all of which are less than 1/10 the diameter of Triton. Triton could not have condensed from the primordial Solar Nebula in this configuration; it must have formed elsewhere (perhaps in the Kuiper Belt ?) and later been captured by Neptune (perhaps involving a collision with another now shattered Neptunian moon). A capture scenario could account not only for Triton's orbit but also for the unusual orbit of Nereid and provide the energy needed to melt and differentiate Triton's interior. Because of its retrograde orbit, tidal interactions between Neptune and Triton remove energy from Triton thus lowering its orbit. At some very distant future time it will either break up (perhaps forming a ring) or crash into Neptune.

The unusual nature of Triton's orbit, the similarity of bulk properties between Pluto and Triton, and the highly eccentric, Neptune-crossing nature of Pluto's orbit suggest some historical connection between them. Exactly what this might be is purely conjecture at this time however. Triton's axis of rotation is also unusual, tilted 157 degrees with respect to Neptune 's axis (which is in turn inclined 30 degrees from the plane of Neptune's orbit). This adds up to an orientation with respect to the Sun somewhat like Uranus 's with polar and equatorial regions alternately pointing toward the Sun. This probably results in radical seasonal changes as one pole then the other moves into the sunlight. During the Voyager 2 encounter, Triton's south pole was facing the Sun. Triton's density (2.0) is slightly greater than that of Saturn's icy moons (e.g. Rhea ). Triton is probably only about 25% water ice with remainder rocky material. Voyager found that Triton has an atmosphere, albeit a very tenuous one (about 0.01 millibar ), composed mostly of nitrogen with a small amount of methane.

A thin haze extends up 5-10 km. The temperature at the surface of Triton is only 34.5 K (-235 C, -391 F), as cold as Pluto. This is due in part to its high albedo (.7 - .8) which means that little of the Sun's meager light is absorbed. At this temperature methane, nitrogen and carbon dioxide all freeze solid. There are very few craters visible; the surface is relatively young . Almost the entire southern hemisphere is covered with an "ice cap" of frozen nitrogen and methane (right). There are extensive ridges and valleys in complex patterns all over Triton's surface. These are probably the result of freezing/thawing cycles. The most interesting (and totally unexpected) features of this unusually interesting world are the ice volcanoes. The eruptive material is probably liquid nitrogen, dust, or methane compounds from beneath the surface. One of Voyager's images shows an actual plume rising 8 km above the surface and extending 140 km "downwind" (left).

Triton, Io and Venus are the only bodies in the solar system besides Earth that are known to be volcanically active at the present time (though Mars clearly was in the past). It's also interesting to note that very different volcanic processes occur in the outer solar system. Earth's and Venus' (and Mars') eruptions are of rocky material and are driven by internal heat. Io's eruptions are probably sulfur or sulfur compounds driven by tidal interactions with Jupiter. Triton's eruptions are of very volatile compounds like nitrogen or methane driven by seasonal heating from the Sun. More about Triton Neptune Neptune Neptune was discovered by astronomers in the year 1846. The temperature The temperature in this planet is cold, -370 degrees. The air and water would freeze in it. Distance from the sun Neptuneï¿½s distance from the sun is 2799 million miles or 4504 million km, the location of the planet Neptune is between Uranus and Pluto. The Air Neptune is bright blue instead of green because its atmosphere is made of different kinds of gasses, it has methane. Special characteristics Neptune has 8 moons and the largest are called Triton and Nereid. There is no oxygen.

Every 165 Neptune completes its orbit around the sun. Water Inside the rocky core there is water, ammonia and methane slush. They can`t drink or use water because it will freeze. Report on a planet ï¿½ 2nd draft Neptune Neptune was discovered by astronomers in the year 1846. The temperature The temperature in this planet is cold, -370 degrees. The air and water would freeze in it. Distance from the sun Distance from the sun is 2799 million milesor 4504 million km, the location is the eight planet from the sun our Solar System. The Air Neptune is bright blue instead of green because its atmosphere is made of different kinds of gasses, it has methane. There are colorful bands of clouds in the atmosphere. Special characteristics Neptune has 8 moons and the largest are called Triton and Nereid. the great spot is the size of ear Finish this section please. Children: ï¿½ Can you write the names of the members of the group so that I know who I am writing for, please? ï¿½ Remember to include a bibliography. ï¿½ Here is a checklist for you to correct your final copy and the correcting code.

Word order or word choice Punctuation Have you put a title and subtitles on your report? Have you described or introduced the subject of your report? Have you finished your report with a conclusion? Have you organized your report into paragraphs? Does the order make sense? Did you use impersonal writing? Is all of your spelling correct? Is your punctuation correct? Is your report in the present tense? Report on a planet - 1st draft Neptune was discovered by astronomers in the year 1846 The temperature The temperature in this planet is cold and -370 degrees and very cold in Neptune How would the temperature affect life on this planet? Distance from the sun Distance from the sun is 2799 million miles 4504 million km. The location is the eight planet from the sun our Solar System. How many moons has. Neptune has 13 moons around Neptune and 8 moons called Triton and Nereid. Check your sentences to make sure they make sense. The air Neptune is bright blue instead of green because its atmosphere is made of different kinds of gases they are called methane. These colorful bands of clouds are in the atmosphere. Conclusion People canï¿½t live in Neptune because they could freeze.

And people would die and because there they canï¿½t plant plants, vegetables, fruits etc. This last sentence needs to be completed, it sounds really interesting!! Children: ï¿½ You have tried to write your report including technical vocabulary and the simple present tense. ï¿½ Check the research guide to make sure you have included all the subtitles needed. ï¿½ Remember to include a conclusion and bibliography. Neptune Has 14 Moons: Neptunian Satellite Facts (Infographic) Fourteen moons orbit Neptune, including enigmatic Triton, which moves backward in its orbit. Credit: by Karl Tate, Infographics Artist Of the 14 satellites of Neptune, the largest is Triton, which is in a retrograde (backward) orbit around the planet. Triton is the largest moon in the solar system to do this. On July 15, a 14th moon of Neptune , provisionally called S/2004 N 1, was announced. Neptune has seven inner moons. Their orbits lie among several faint rings and partial rings composed of dust and ice particles.

Outwards from Neptune, the inner moons are Naiad, Thalassa, Despina, Galatea, Larissa, S/2004 N 1 and Proteus. Next outward from Neptune , Triton is one of four moons in the solar system known to have an atmosphere. The thin nitrogen haze is thought to have evaporated off of the frozen surface. Triton is Neptune's largest moon , at 1,677 miles (2,700 km) in diameter. Because Triton moves backward in its orbit, astronomers think the icy moon formed in the frozen Kuiper belt, located in the outer solar system. Later, Neptune's gravity captured Triton. Neptune Quiz: How Well Do You Know the Other Blue Planet? After Triton comes Nereid. At 211 miles (340 km) in diameter, Nereid is one of the largest irregular moons in the solar system . Irregular moons have orbits that are highly inclined to the planet's equator. Much further out than Nereid orbit five outer moons, Halimede, Sao, Laomedeia, Neso and Psmathe. These irregular moons travel in highly tilted orbits.

Neptune And its known satellites and rings. See also the Voyager 2 spacecraft, the only one to fly by Neptune. Seventy days worth of solar system observations from NASA’s Kepler spacecraft, taken during its reinvented K2 mission, are highlighted in this sped-up movie. The planet Neptune appears on day 15, followed by its moon Triton, which looks small and faint. Keen-eyed observers can also spot Neptune’s tiny moon Nereid at day 24. Neptune is the flickering white streak; it is so bright that its image floods the camera producing the white artifacts. Triton is the yellow spot very close to, and circling, Neptune. Nereid trails several days later. A full description is here. And the Some Basic Facts about Neptune Neptune showing some spots probably in its atmosphere Neptune is the eighth planet from the Sun in the Solar System , and never known to the ancients. Its discovery in 1846 is clothed in controversy, though Galileo is reported to have seen it in 1612 and 1613, not recognising its significance. It has 13 known satellites, named after lesser sea gods than Neptune.

The satellites are Triton , Nereid , and several other small objects first seen in recent years. It has a ring system , exhibiting significant differences from those of other ringed planets. Neptune orbits the Sun once in 60,190.03 Earth days (164.79 years, or 89,666 Neptune solar days). Neptune’s average distance from the Sun is 4,503,443,661 km (30.10366151 AU) though this can vary between 4,452,940,833 km (29.76607095 AU) and 4,553,946,490 km (30.44125206 AU), an eccentricity of 0.011214269.

Its equatorial radius is 24,764±15 km (3.883 Earths) and its polar radius is 24,341±30 km (3.829 Earths), a flattening of 0.0171±0.0013. The surface area is 7.6183×109 km2 (14.98 Earths), and the volume is 6.254×1013 km3 (57.74 Earths). Its mass is 1.0243×1026 kg (17.147 Earths or 5.15×10−5 Suns). Its mean density is 1.638 g/cm3, so, although almost a twin of Uranus in size it is denser. The sidereal rotational period of Neptune is 16 hours, 6 minutes, 36 seconds. Voyager 2 is the only spacecraft to have visited Neptune, and it continued on into the outer reaches of the solar system. So far as I know, no other plans exist for another visitor.

See Wikipedia for more information about Neptune. More about the moons of Neptune in Wikipedia and Seasky•Org . Two asteroids share the same names as moons of Neptune: 74 Galatea and 1162 Larissa. Neptune’s Magnetosphere Neptune resembles Uranus in its magnetosphere, with a magnetic field strongly tilted relative to its rotational axis at 47° and offset at least 0.55 radii, or about 13,500 km from the planet’s physical centre. Before Voyager 2’s arrival at Neptune, it was hypothesised that Uranus’s tilted magnetosphere was the result of its sideways rotation. In comparing the magnetic fields of the two planets, scientists now think the extreme orientation may be characteristic of flows in the planets’ interiors. This field may be generated by convective fluid motions in a thin spherical shell of electrically conducting liquids (probably a combination of ammonia, methane and water) resulting in a dynamo action. Rings of Neptune [Right] This 591-second exposure of the rings of Neptune was taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged.

Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. At their densest, the rings are comparable to the less dense portions of Saturn’s main rings such as the C ring and the Cassini Division, but much of Neptune’s ring system is quite tenuous, faint and dusty, more closely resembling the rings of Jupiter. The three main rings are the narrow Adams Ring, 63,000 km from the centre of Neptune, the Le Verrier Ring, at 53,000 km, and the broader, fainter Galle Ring, at 42,000 km. A faint outward extension to the Le Verrier Ring has been named Lassell; it is bounded at its outer edge by the Arago Ring at 57,000 km.

These rings have a clumpy structure, the cause of which is not currently understood but which may be due to the gravitational interaction with small moons in orbit near them. The outermost ring, Adams, contains five prominent arcs now named Courage, Liberté, Egalité 1, Egalité 2 and Fraternité (Courage, Liberty, Equality and Fraternity). The existence of arcs was difficult to explain because the laws of motion would predict that arcs would spread out into a uniform ring over very short timescales. How the arcs are stabilized is still under debate, though Astronomers now believe that the arcs are corralled into their current form by the gravitational effects of Galatea, a moon just inward from the ring. The arcs occupy a narrow range of orbital longitudes and are remarkably stable, having changed only slightly since their initial detection in 1980. The rings of Neptune are made of extremely dark material, likely organic compounds processed by radiation, similar to that found in the rings of Uranus. The proportion of dust in the rings (between 20% and 70%) is high, while their optical depth is low to moderate, at less than 0.1.

Neptune Trojans Neptune trojans are bodies in orbit around the Sun, that have the same orbital period as Neptune, and follow roughly the same orbital path. Nine are currently known, of which six orbit near the Sun–Neptune L4 Lagrangian point 60° ahead of Neptune and three orbit near Neptune’s L5 region 60° behind Neptune. The Neptune trojans are so termed by analogy with Jupiter’s trojan asteroids ; it is speculated that there may be ten times as many Neptune trojans as Jupiter trojans. The first Neptune trojan was discovered in 2001, the fifth known populated stable grouping of small bodies in the Solar System after the asteroid belt, the Jupiter trojans, the trans-Neptunian objects and the Mars trojans.

The known Neptune trojans in the L4 zone are: 2001 QR322, 2004 UP10, 2005 TN53, 2005 TO74, 2006 RJ103 and 2007 VL305; those at L5 are: 2004 KV18, 2008 LC18 and 2011 HM102. In addition 2005 TN74 and (309239) 2007 RW10 were believed to be Neptune trojans at the time of their discovery, but further observations have found that they are not. 2005 TN74 is currently thought to be in a 3:5 resonance with Neptune. (309239) 2007 RW10 is currently following a quasi-satellite loop around Neptune. Neptune’s Moon Triton Triton is the largest moon of Neptune; it is the only large moon in the Solar System with a retrograde orbit (in the opposite direction to its planet’s rotation).

At 2,700 km in diameter, it is the seventh-largest moon in the Solar System. Because of its retrograde orbit and composition similar to that of Pluto , Triton is thought to have been captured from the Kuiper belt . Triton has a surface of mostly frozen nitrogen, a mostly water-ice crust, an icy mantle and a substantial core of rock and metal. The core makes up two-thirds of its total mass. Triton has a mean density of 2.061 g/cm3 and is composed of approximately 15 to 35% water ice. Neptune’s largest moon Triton has plumes of gas coming from inside Here’s more information about Triton , especially its orbital characteristics and surface features. [Left] A Voyager 2 photomosaic of Triton’s sub-Neptunian hemisphere. The bright, slightly pinkish, south polar cap at bottom is composed of nitrogen and methane ice and is streaked by dust deposits left by nitrogen gas geysers. The mostly darker region above it includes Triton’s “cantaloupe terrain” and cryovolcanic and tectonic features.

Near the lower right limb are several dark maculae (“strange spots”) Triton’s Geysers [Right] Triton is one of the few moons in the Solar System known to be geologically active. As a consequence, its surface is relatively young, with a complex geological history revealed in intricate and mysterious cryovolcanic and tectonic terrains. Part of its crust is dotted with geysers thought to erupt nitrogen. Triton has a tenuous nitrogen atmosphere less than 1/70,000 the pressure of Earth’s atmosphere at sea level. Neptune’s Moon Proteus Proteus is the second largest moon of Neptune after the mysterious Triton. Proteus was discovered only in 1989 by the Voyager 2 spacecraft. This is unusual since Neptune has a smaller moon – Nereid – which was discovered 33 years earlier from Earth. The reason Proteus was not discovered sooner is that its surface is very dark and it orbits much closer to Neptune. Proteus has an odd box-like shape and were it even slightly more massive, its own gravity would cause it to reform itself into a sphere.

Proteus, despite being more than 400 km in diameter has a somewhat irregular shape with several slightly concave facets and relief as high as 20 km. Its surface is dark, neutral in colour and heavily cratered. The largest crater is more than 200 km in diameter. There are also a number of scarps, grooves and valleys related to large craters. Proteus is probably not an original body that formed with Neptune; it may have accreted later from the debris created when the largest Neptunian satellite Triton was captured. Neptune’s Moon Nereid Nereid, the third-largest moon of Neptune, has one of the most eccentric orbits of any satellite in the solar system. The eccentricity of 0.7512 gives it an apoapsis of 9,655,000 km that is seven times its periapsis distance (1,372,000 km) from Neptune. It is about 340 km in diameter. Other Moons of Neptune Neptune’s innermost four moons – Naiad, Thalassa, Despina and Galatea – orbit close enough to be within Neptune’s rings.

In order of their distances from Neptune, the regular Neptunian moons are: Naiad: 33±3 km in radius, Thalassa: 41±3 km, Despina: 75±3 km (which may be a shepherd moon of the LeVerrier Ring, as its orbit lies just inside this ring), Galatea: 88±4 km (apparently a shepherd moon of the Adams Ring), Larissa: 97±3 km, and Proteus: 210±7 km. Again, in order of distance from Neptune are the irregular moons, a group that includes both prograde and retrograde objects: Triton: 1,353.4±0.9 km (0.2122 Earths), Nereid: 170±25 km, Halimede*: about 62 km, eccentricity 0.2646, Sao: about 22 km, eccentricity 0.1365, Laomedeia: about 21 km, Neso*: about 30 km and Psamathe*: about 19 km.

‘*’ indicates an orbit around Neptune opposite to the planet’s rotation, and suggests that these moons and other small ones are captured asteroids . Despina is irregularly shaped and shows no sign of any geological modification. It is likely that Despina, Galatea and Larissa are rubble piles re-accreted from fragments of Neptune’s original satellites, which were smashed up by perturbations from Triton soon after that moon’s capture into a very eccentric initial orbit. Despina’s orbit lies close to but outside of the orbit of Thalassa and just inside the Le Verrier ring. The orbits of Despina, Galatea and Larissa all lie below Neptune’s synchronous orbit radius. They are slowly spiralling inward due to tidal decceleration and may eventually impact Neptune’s atmosphere, or break up into planetary rings upon passing its Roche limit due to tidal stretching. Larissa is the fourth-largest satellite of Neptune, is irregular (non-spherical) in shape and appears to be heavily cratered, with no sign of any geological modification. Little else is known about it. Larissa’s orbit is circular but not perfectly so. Halimede has the second most eccentric and third most inclined orbit around Neptune.

Sao orbits Neptune at a distance of about 22.4 million km and is about 44 km in diameter (assuming an albedo of 0.04). It follows an exceptionally inclined and moderately eccentric orbit. The satellite is in so-called Kozai resonance, i.e. its inclination and eccentricity are coupled (the inclination of the orbit decreases while eccentricity increases and vice versa). Laomedeia orbits Neptune at a distance of about 23,571,000 km and is about 42 km in diameter (assuming albedo of 0.04). Neso orbits Neptune at a distance of more than 48 Gm (million km), making it the most distant known moon of any planet. Such distances are of the order of magnitude of heliocentric distances of inner planets rather than moons; at apocentre the satellite is more than 72 Gm (72 million km) from the planet to compare with Mercury’s aphelion of about 70 Gm! It follows a highly inclined and highly eccentric orbit.

Psamathe orbits Neptune at a distance of about 46,695,000 km and requires almost 25 Earth years to make one orbit. The orbit of this satellite is close to the theoretical stable separation from Neptune for a body in a retrograde orbit. Given the similarity of this moon’s orbital parameters with Neso, it was suggested that both irregular satellites could have a common origin in the break-up of a larger moon. Both are further from their primary than any other known moon in the Solar System. The moons of Neptune The moons of Neptune September 9, 2015 by Matt Williams, Universe Today Neptune and its moons. Credit: NASA Neptune, that icy gas giant that is the eight planet from our Sun, was discovered in 1846 by two astronomers – Urbain Le Verrier and Johann Galle. In keeping with the convention of planetary nomenclature, Neptune was named after the Roman god of the sea (the equivalent to the Greek Poseidon). And just seventeen days after it was discovered, astronomers began to notice that it too had a system of moons. Initially, only Triton – Neptune's largest moon – could be observed.

But by the mid-20th century and after, thanks to improvements in ground-based telescopes and the development of robotic space probes, many more moons would be discovered. Neptune now has 14 recognized satellites, and in honor of of their parent planet, all are named for minor water deities in Greek mythology. Discovery and Naming: Triton, being the largest and most massive of Neptune's moons, was the first to be discovered. It was observed by William Lassell on October 10th, 1846, just seventeen days after Neptune was discovered. It would be almost a century before any other moons would be discovered. The first was Nereid, Neptune's second largest and most massive moon, which was discovered on May 1st, 1949, by Gerard P. Kuiper (for whom the Kuiper Belt is named) using photographic plates from the McDonald Observatory in Fort Davis, Texas. The third moon, later named Larissa, was first observed by Harold J. Reitsema, William B. Hubbard, Larry A. Lebofsky and David J. Tholen on May 24th, 1981.

The discovery of this moon was purely fortuitous, and occurred as a result of the ongoing search for rings similar to those discovered around Uranus four years earlier. If rings were in fact present, the star's luminosity would decrease slightly just before the planet's closest approach. While observing a star's close approach to Neptune, the star's luminosity dipped, but only for several seconds. This indicated the presence of a moon rather than a ring. No further moons were found until Voyager 2 flew by Neptune in 1989. In the course of passing through the system, the space probe rediscovered Larissa and discovered five additional inner moons: Naiad, Thalassa, Despina, Galatea and Proteus. In 2001, two surveys using large ground-based telescopes – the Cerro Tololo Inter-American Observatory and the Canada-France-Hawaii telescopes – found five additional outer moons bringing the total to thirteen. Follow-up surveys by two teams in 2002 and 2003 respectively re-observed all five of these moons – which were Halimede, Sao, Psamathe, Laomedeia, and Neso.

And then on July 15th, 2013, a team of astronomers led by Mark R. Showalter of the SETI Institute revealed that they had discovered a previously unknown fourteenth moon in images taken by the Hubble Space Telescope from 2004–2009. The as yet unnamed fourteenth moon, currently identified as S/2004 N 1, is thought to measure no more than 16–20 km in diameter. In keeping with astronomical convention, Neptune's moons are all taken from Greek and Roman mythology. In this case, all are named for gods of the sea, or for the children of Poseidon (which include Triton, Proteus, Depsina and Thalassa), minor Greek water dieties (Naiad and Nereid) or Nereids , the water nymphs in Greek mythology (Halimede, Galatea, Neso, Sao, Laomedeia and Psamathe). However, many of the moons were not officially named until the 20th century.

The name Triton, which was originally suggested by Camille Flammarion in his 1880 book Astronomie Populaire , but not into common usage until at least the 1930s. Inner (Regular) Moons: Neptune's Regular Moons are those located closest to the planet and which follow circular prograde orbits that lie in the planet's equatorial plane. They are, in order of distance from Neptune: Naiad (48,227 km), Thalassa (50,074 km), Despina (52,526 km), Galatea (61,953 km), Larissa (73,548 km), S/2004 N 1 (105,300 ± 50 km), and Proteus (117,646 km). All but the outer two are within Neptune-synchronous orbit (meaning that orbit Neptune slower than it's orbital period (0.6713 days) and thus are being tidally decelerated. The inner moons are closely associated with Neptune's narrow ring system.

The two innermost satellites, Naiad and Thalassa, orbit between the Galle and LeVerrier rings, whereas Despina orbits just inside the LeVerrier ring. The next moon, Galatea, orbits just inside the most prominent Adams ring and its gravity helps maintaining the ring by containing its particles. Hubble Space Telescope composite picture showing the location of a newly discovered moon, designated S/2004 N 1. Credit: NASA, ESA, and M. Showalter (SETI Institute). Based on observational data and assumed densities, Naiad measures 96 × 60 × 52 km and weighs approximately 1.9 x 1017 kg.

Meanwhile, Thalassa measures 108 x 100 × 52 km and weighs 3.5 x 1017 kg; Despina measures 180 x 148 x 128 and weighs 21 x 1017 kg; Galatea measures 204 x 184 x 144 and weighs 37.5 x 1017 kg; Larissa measures 216 x 204 x 168 and weighs 49.5 x 1017 kg; S/2004 N1 measures 16-20 km in diameter and weighs 0.5 ± 0.4 x 1017 kg; and Proteus measures 436 x 416 x 402 and weighs 50.35 x 1017 kg. Only the two largest regular moons have been imaged with a resolution sufficient to discern their shapes and surface features. Nevertheless, with the exception of Larissa and Proteus (which are largely rounded) all of Neptune's inner moons are believed to be elongated in shape.

In addition, all the inner moons dark objects, with geometric albedo ranging from 7 to 10%. Their spectra also indicated that they are made from water ice contaminated by some very dark material, probably organic compounds. In this respect, the inner Neptunian moons are similar to the inner moons of Uranus. Outer (Irregular) Moons: Neptune's irregular moons consist of the planet's remaining satellites (including Triton). They generally follow inclined eccentric and often retrograde orbits far from Neptune; the only exception is Triton, which orbits close to the planet following a circular orbit, though retrograde and inclined. In order of their distance from the planet, the irregular moons are Triton, Nereid, Halimede, Sao, Laomedeia, Neso and Psamathe, a group that includes both prograde and retrograde objects. With the exception of Triton and Nereid, Neptune's irregular moons are similar to those of other giant planets and are believed to have been gravitationally captured by Neptune.

In terms of size and mass, the irregular moons are relatively consistent, ranging from approximately 40 km in diameter and 4 x 1016 kg in mass (Psamathe) to 62 km and 16 x 1016 kg for Halimede. Triton and Nereid: Triton and Nereid are unusual irregular satellites and are thus treated separately from the other five irregular Neptunian moons. Between these two and the other irregular moons, four major differences have been noted. First of all, they are the largest two known irregular moons in the Solar System. Triton itself is almost an order of magnitude larger than all other known irregular moons and comprises more than 99.5% of all the mass known to orbit Neptune (including the planet's rings and thirteen other known moons). Secondly, they both have atypically small semi-major axes, with Triton's being over an order of magnitude smaller than those of all other known irregular moons. Thirdly, they both have unusual orbital eccentricities: Nereid has one of the most eccentric orbits of any known irregular satellite, and Triton's orbit is a nearly perfect circle.

Finally, Nereid also has the lowest inclination of any known irregular satellite With a mean diameter of around 2700 km and a mass of 214080 ± 520 x 1017 kg, Triton is the largest of Neptune's moons, and the only one large enough to achieve hydrostatic equilibrium (i.e. is spherical in shape). At a distance of 354,759 km from Neptune, it also sits between the planet's inner and outer moons. The video will load shortly Triton follows a retrograde and quasi-circular orbit, and is composed largely of nitrogen, methane, carbon dioxide and water ices. With a geometric albedo of more than 70% and a Bond albedo as high as 90%, it is also one of the brightest objects in the Solar System. The surface has a reddish tint, owning to the interaction of ultraviolet radiation and methane, causing tholins. Triton is also one of the coldest moons in the Solar System, with surface temperature of about 38 K (235.2 °C).

However, owing to the moon being geologically active (which results in cryovolcanism) and surface temperature variations that cause sublimation, Triton is one of only two moons in the Solar System that has a substantial atmosphere. Much like it's surface, this atmosphere is composed primarily of nitrogen with small amounts of methane and carbon monoxide, and with an estimated pressure of about 14 ?bar. Triton has a relatively high density of about 2 g/cm3 indicating that rocks constitute about two thirds of its mass, and ices (mainly water ice) the remaining one third. There also may be a layer of liquid water deep inside Triton, forming a subterranean ocean. Surface features include the large southern polar cap, older cratered planes cross-cut by graben and scarps, as well as youthful features caused by endogenic resurfacing. Because of its retrograde orbit and relative proximity to Neptune (closer than the Moon is to Earth), Triton is grouped with the planet's irregular moons (see below). In addition, it is believed to be a captured object, possibly a dwarf planet that was once part of the Kuiper Belt.

At the same time, these orbital characteristics are the reason why Triton experiences tidal deceleration. and will eventually spiral inward and collide with the planet in about 3.6 billion years. Nereid is the third-largest moon of Neptune. It has a prograde but very eccentric orbit and is believed to be a former regular satellite that was scattered to its current orbit through gravitational interactions during Triton's capture. Water ice has been spectroscopically detected on its surface. Nereid shows large, irregular variations in its visible magnitude, which are probably caused by forced precession or chaotic rotation combined with an elongated shape and bright or dark spots on the surface. The video will load shortly Formation: Given the lopsided distribution of mass in its moons, it is widely believed that Triton was captured after the formation of Neptune's original satellite system – much of which would have been destroyed in the process of capture. Many theories have been offered regarding the mechanisms of its capture over the years. The video will load shortly The most widely-accepted is that Triton is a surviving member of a binary Kuiper Belt Object that was disrupted with an encounter with Neptune.

In this scenario, Triton's captured was the result of a three-body encounter, where it fell into a retrograde orbit while the other object was either destroyed or ejected in the process. Triton's orbit upon capture would have been highly eccentric, and would have caused chaotic perturbations in the orbits of the original inner Neptunian satellites, causing them to collide and reduce to a disc of rubble. Only after Triton's orbit became circular again could some of the rubble re-accrete into the present-day regular moons. This means it is likely that Neptune's present inner satellites are not the original bodies that formed with Neptune. Global Color Mosaic of Triton, taken by Voyager 2 in 1989. Credit: NASA/JPL/USGS Numerical simulations show that there is a 0.41 probability that the moon Halimede collided with Nereid at some time in the past. Although it is not known whether any collision has taken place, both moons appear to have similar ("grey") colors, implying that Halimede could be a fragment of Nereid. Given its distance from the Sun, the only mission to ever study Neptune and its moons up close was the Voyager 2 mission.

And though no missions are currently being planned, several proposals have been made that would see a robotic probe dispatched to the system sometime in the late 2020s or early 2030s. Using the CRIRES instrument on ESO’s Very Large Telescope, a team of astronomers has been able to see that the summer is in full swing in Triton’s southern hemisphere. Credit: ESO

Question: Which planet's two largest moons have the suitably watery names of Triton and Nereid?
Answer: NEPTUNE