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Encyclopedia > Triton (moon)
Triton
Discovery
Discovered by: William Lassell
Discovery date: October 10, 1846
Orbital characteristics
Semi-major axis: 354,800 km
Eccentricity: 0.0000
Orbital period: −5.877 d
(retrograde)
Inclination: 130.267° (to the ecliptic)
157.340° (to Neptune's equator)
130.063° (to Neptune's orbit)
Satellite of: Neptune
Physical characteristics
Mean radius: 1353.4 ± 0.9 km[1] (0.2122 Earths)
Surface area: 23,018,000 km²
Volume: 10,384,000,000 km³
Mass: 2.147×1022 kg (0.00359 Earths)
Mean density: 2.05 g/cm³
Equatorial surface gravity: 0.782 m/s²
Escape velocity: 1.455 km/s
Rotation period: synchronous
Sidereal rotation period: 5 d, 21 h, 2 min, 28s
Axial tilt: zero
Albedo: 0.76
Temperature: 34.5 K
Atmosphere
Surface pressure: 0.001 kPa
Composition: 99.9% nitrogen
0.1% methane

Triton (trye'-tən, IPA: [ˈtraɪtn̩], Greek Τρίτων), or Neptune I, is the planet Neptune's largest moon. Triton has a complex geological history and it is believed to have a relatively young surface. It was discovered by British astronomer William Lassell on October 10, 1846, just 17 days after the planet itself was discovered by German astronomer Johann Gottfried Galle. It is also believed to be a captured Kuiper Belt object. Download high resolution version (1024x796, 150 KB)A color mosaic of Triton, Neptunes moon (large). ... William Lassell (June 18, 1799 – October 5, 1880) was a British astronomer, born in Bolton, Lancashire, England. ... October 10 is the 283rd day of the year (284th in leap years). ... 1846 was a common year starting on Thursday (see link for calendar). ... m. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... A kilometer (Commonwealth spelling: kilometre), symbol: km is a unit of length in the metric system equal to 1,000 metres (from the Greek words χίλια (khilia) = thousand and μέτρο (metro) = count/measure). ... (This page refers to eccitricity in astrodynamics. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... Prograde motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called direct motion, especially in astrology. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ... In mathematics, a spheroid is a quadric surface in three dimensions obtained by rotating an ellipse about one of its principal axes. ... The volume of a solid object is the three-dimensional concept of how much space it occupies, often quantified numerically. ... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... BIC pen cap, about 1 gram. ... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centimetre. ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... Acceleration is the time rate of change of velocity, and at any point on a velocity-time graph, it is given by the slope of the tangent to that point basicly. ... Space Shuttle Atlantis launches on mission STS-71. ... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis. ... In astronomy, synchronous rotation is a planetological term describing a body orbiting another, where the orbiting body takes as long to rotate on its axis as it does to make one orbit; and therefore always keeps the same hemisphere pointed at the body it is orbiting. ... On a prograde planet like the Earth, the sidereal day is shorter than the solar day. ... In astronomy, Axial tilt is the inclination angle of a planets rotational axis in relation to a perpendicular to its orbital plane. ... Albedo is the ratio of reflected to incident electromagnetic radiation power. ... Fig. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ... The pascal (symbol: Pa) is the SI derived unit of pressure or stress (also: Youngs modulus and tensile strength). ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Methane is a chemical compound with the molecular formula CH4. ... Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... The eight planets and three dwarf planets of the Solar System. ... Adjectives: Neptunian Atmosphere Surface pressure: ≫ 100 kPa (cloud level) Composition: 80% ± 3. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... An astronomer or astrophysicist is a person whose area of interest is astronomy or astrophysics. ... William Lassell (June 18, 1799 – October 5, 1880) was a British astronomer, born in Bolton, Lancashire, England. ... October 10 is the 283rd day of the year (284th in leap years). ... 1846 was a common year starting on Thursday (see link for calendar). ... Johann Gottfried Galle (June 9, 1812 – July 10, 1910) was a German astronomer at the Berlin Observatory who, with help from Urbain Le Verrier, sighted Neptune on September 23, 1846. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ...

Contents

Name

Triton is named after the Greek sea god Triton, the son of Neptune. The name was first proposed by Camille Flammarion in 1880.[2] It is perhaps strange that Lassell, the discoverer, did not see fit to name his own discovery, since he gave names a few years later to his subsequent discoveries of an eighth moon of Saturn (Hyperion), and of the third and fourth moons of Uranus (Ariel and Umbriel). Triton is a Greek god, the messenger of the deep. ... Neptune is usually depicted with a trident, as seen here in this statue by Jean de Boulogne in Bologna, Italy. ... Camille Flammarion Camille Flammarion (February 26, 1842 – June 3, 1925) was a French astronomer and author. ... Year 1880 (MDCCCLXXX) was a leap year starting on Thursday (link will display the full calendar). ... Adjectives: Saturnian Atmosphere Surface pressure: 140 kPa Composition: >93% hydrogen >5% helium 0. ... Hyperion (IPA: , Greek Ὑπερίων) is a moon of Saturn discovered by William Cranch Bond, George Phillips Bond and William Lassell in 1848. ... Atmospheric characteristics Atmospheric pressure 120 kPa Hydrogen 83% Helium 15% Methane 1. ... Atmospheric pressure 0 kPa Ariel (air-ee-əl, IPA ) is a moon of Uranus discovered on 24 October 1851 by William Lassell. ... Atmospheric pressure 0 kPa Umbriel (um-bree-əl, IPA ) is a moon of Uranus discovered on 1851-10-24 by William Lassell. ...


Orbit

Retrograde 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 opposite to the planet's rotation). Most of the outer moons of Jupiter and Saturn also have retrograde orbits, as do some of Uranus' outer moons. But all of those other retrograde moons are quite small; 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 or turn retrograde through collision. The latter scenario is the least likely with Triton and it is therefore suspected that it is a captured Kuiper belt object. This article is about retrograde motion. ... Adjectives: Jovian Atmosphere Surface pressure: 20–200 kPa[4] (cloud layer) Composition: ~86% H2 ~13% Helium 0. ... Adjectives: Saturnian Atmosphere Surface pressure: 140 kPa Composition: >93% hydrogen >5% helium 0. ... Adjectives: Uranian Atmosphere Surface pressure: 120 kPa (at the cloud level) Composition: 83% Hydrogen 15% Helium 1. ... For other meanings see Phoebe. ... This article or section does not cite any references or sources. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ...


Captured Object

The capture of Triton may explain a number of features of the Neptunian system including the extremely eccentric orbit of Neptune's moon Nereid, the scarcity of moons as compared to the other gas giants (Triton's orbit could initially have crossed those of many other lighter moons, dispersing them through gravitational interaction), and the evidence of differentiation in Triton's interior (tidal heating resulting from an eccentric post-capture orbit being circularized could have kept Triton liquid for a billion years). Its similarity in size and composition to Pluto, as well as Pluto's eccentric Neptune-crossing orbit, provide further hints to Triton's possible origin as a Pluto-like planetary body (a.k.a. "plutino," an object in the Kuiper Belt with the same 2:3 orbit resonance as like that of Neptune and Pluto). Nereid (IPA: , IPA: , Greek Νηρηίδα), or Neptune II, is a moon of Neptune. ... “Gravity” redirects here. ... Comet Shoemaker-Levy 9 after breaking up under the influence of Jupiters tidal forces. ... One thousand million (1,000,000,000) is the natural number following 999,999,999 and preceding 1,000,000,001. ... Atmospheric characteristics Atmospheric pressure 0. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ...


Previously A Binary

Theoretical work suggests that prior to the capture Triton may have had a massive companion similar to Pluto's moon Charon. When the binary encountered Neptune, Triton's companion was expelled providing the required mechanism to capture Triton in an orbit around the planet. This theory has several notable advantages, including the fact that binaries are very common among the large Kuiper belt objects, the event was brief but gentle saving Triton from collisional disruption, and events like this may have been common during the formation of Neptune, or later when it migrated outward.[3] Charon (shair-ən or kair-ən (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ...


Due to its retrograde motion, the already-close Tritonian orbit is slowly decaying further from tidal interactions and it is predicted that some 3.6 billion years from now, Triton will pass within its Roche limit.[4] This will result in either a collision with Neptune's atmosphere or the formation of a ring system similar in nature to that found around Saturn. The Roche limit, sometimes referred to as the Roche radius, is the distance within which a celestial body held together only by its own gravity will disintegrate due to a second celestial bodys tidal forces exceeding the first bodys gravitational self-attraction. ... A planetary ring is a ring of dust and other small particles orbiting around a planet in a flat disc-shaped region. ... Adjectives: Saturnian Atmosphere Surface pressure: 140 kPa Composition: >93% hydrogen >5% helium 0. ...


Another unique feature of Triton's orbit, arising from tidal effects on such a large moon so close to its primary in a retrograde orbit, is that it is nearly a perfect circle with an eccentricity of zero as far as measurments can detect.


Physical characteristics

A cloud over the limb of Triton.

Triton has a density of 2.05 g/cm³, and is probably about 25% water ice, with the remainder being rocky material. It has a tenuous nitrogen atmosphere with small amounts of methane. Tritonian atmospheric pressure is only about 0.01 millibar. The surface temperature is at least 35.6 K (−237°C) because Triton's nitrogen ice is in the warmer, hexagonal beta crystalline state, and the phase transition between beta and cubic alpha nitrogen ice is that temperature. An upper limit in the low 40s can be set from vapor pressure equilibrium with nitrogen gas in Triton's atmosphere. This temperature range is colder than Pluto's average equilibrium temperature of 44 K (−229°C). Surprisingly, however, Triton is geologically active; its surface is fresh and sparsely cratered, and the Voyager 2 probe observed numerous icy volcanoes or geysers erupting liquid nitrogen, dust, or methane compounds from beneath the surface in plumes up to 8 km high. This volcanic activity is thought to be driven by seasonal heating from the Sun, unlike the tidal heating responsible for the volcanoes of Io. There are extensive ridges and valleys in complex patterns all over Triton's surface, probably the result of freezing/thawing cycles.[5] Triton's surface area is 23 million km² (4.5% of Earth, or 15.5% of Earth's land area). Image File history File links Download high resolution version (450x900, 19 KB) Summary Original caption released with the image: Limb clouds over Tritons south polar cap. ... Image File history File links Download high resolution version (450x900, 19 KB) Summary Original caption released with the image: Limb clouds over Tritons south polar cap. ... Snowflakes by Wilson Bentley, 1902 Ice is the name given to any one of the 14 known solid phases of water. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Atmospheric characteristics Atmospheric pressure 0. ... Tycho crater on Earths moon. ... Trajectory Voyager 2 is an unmanned interplanetary spacecraft, launched on August 20, 1977. ... Ganesa Macula, a dark feature on Saturns moon Titan, might be a cryovolcanic dome. ... Strokkur geyser, Iceland A geyser is a type of hot spring that erupts periodically, ejecting a column of hot water and steam into the air. ... Comet Shoemaker-Levy 9 after breaking up under the influence of Jupiters tidal forces. ... Atmospheric characteristics Atmospheric pressure trace Sulfur dioxide 90% Io (eye-oe, IPA: , Greek Ῑώ) is the innermost of the four Galilean moons of Jupiter. ... To help compare sizes of different areas, here is a list of areas between 10 million km² and 100 million km². See also areas of other orders of magnitude. ... Square kilometre (US spelling: Square kilometer), symbol km², is an SI unit of surface area. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ...

Triton is a geologically active moon with a complex and young surface.

Download high resolution version (893x749, 226 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Download high resolution version (893x749, 226 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Planetary geology

Triton has a similar size, density, and chemical composition to that of Pluto. Noting the eccentric orbit of Pluto, which crosses the orbit of Neptune, we can postulate the origin of Triton as a similar planetoid captured by Neptune. Therefore, Triton may well have been formed far from Neptune, in the far reaches of the solar system. Adjectives: Plutonian Atmosphere Surface pressure: 0. ... Adjectives: Neptunian Atmosphere Surface pressure: ≫ 100 kPa (cloud level) Composition: 80% ± 3. ... Planetoid (meaning planet-like) is an old synonym of asteroid. ...


Even though there are various differences between Triton and other frozen moons of the solar system, the terrain is similar to Ariel (moon of Uranus), Enceladus (moon of Saturn), and three moons of Jupiter: Io, Europa, and Ganymede. It is also similar to Mars with its polar caps. Atmospheric pressure 0 kPa Ariel (air-ee-əl, IPA ) is a moon of Uranus discovered on 24 October 1851 by William Lassell. ... Adjectives: Uranian Atmosphere Surface pressure: 120 kPa (at the cloud level) Composition: 83% Hydrogen 15% Helium 1. ... [5] Atmospheric characteristics Pressure trace, significant spatial variability [6], [7] Water vapour 91% [8] Carbon dioxide 3. ... Adjectives: Saturnian Atmosphere Surface pressure: 140 kPa Composition: >93% hydrogen >5% helium 0. ... Atmospheric characteristics Atmospheric pressure trace Sulfur dioxide 90% Io (eye-oe, IPA: , Greek Ῑώ) is the innermost of the four Galilean moons of Jupiter. ... Apparent magnitude: 5. ... This article or section does not adequately cite its references or sources. ... Adjectives: Martian Atmosphere Surface pressure: 0. ...


The gravitational effect of Triton on the trajectory of Voyager 2 suggests that the icy mantle covers a substantial core of rock (probably containing metal). The core makes up two thirds of the total mass of Triton, which is the third most of any other moon in the solar system after Io and Europa. Triton has a mean density of 2.05 g/cm³ and is composed of approximately 25% of water ice, especially in the mantle.


The surface is mainly covered with frozen nitrogen and water, but it also has dry ice (carbon dioxide), water ice, carbon monoxide ice, and methane. It is thought that there could be large amounts of ammonia on the surface. Triton is very bright, reflecting 60%–95% of the sunlight that reaches it while Earth's moon reflects only 11%. Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ... Ammonia is a compound with the formula NH3. ...


General topography

The total surface area is about 15.5% of the land area of Earth, or 4.5% of the total area. The dimensions of Triton suggest that there are regions with different densities, varying from 2.07 to 2.3 g/cm³. There are areas with rocky outcrops, and there are areas of canyons. Icy substances, mainly frozen methane covers part of the surface. Methane is a chemical compound with the molecular formula CH4. ...


The southern polar region of Triton is covered by a highly reflective cap of frozen nitrogen and methane sprinkled by impact craters and openings of geysers. Little is known about the north pole of Triton because it was already in the penumbra when Voyager 2 visited Triton. However, it is thought that it must have a polar cap.[citation needed]

The few craters that exist on Triton reveal intense geologic activity.

In the equatorial region, long faults with parallel mountain ranges of ice expelled from the interior cross complex terrain with valleys. Yasu Sulci, Ho Sulci, and Lo Sulci are some of these systems known as sulci, a term that means 'ridges'. East of these ridges are the plains of Ryugu Planitia and Sipapu Planitia and the plateau of Cipango Planum. Image File history File links Download high resolution version (1885x1903, 451 KB) Craters in Triton, moon of Neptune. ... Image File history File links Download high resolution version (1885x1903, 451 KB) Craters in Triton, moon of Neptune. ...


The plains zones of Sipagu Planitia and Abatos Planum in the southern hemisphere meet surrounded by black points, the maculae. Two groups of maculae, Akupara Maculae and Zin Maculae make up the eastern part of Abatos Planum. These marks appear to be deposits on the surface left by ice that evaporated, but neither the composition nor the origin of the ice is known.


Next to Sipapu and Abatos Planum, there is a fresh crater that is 27 km in diameter called Mazomba. Following northwest, there are two smaller craters (Kurma and Ilomba) following the Mazomba crater almost in a straight line. The majority of the holes and wasteland was caused by slipping and collapse of ice, opposite of what happened on other moons, where impact craters dominate the surface. However, Voyager photographed a 500 km impact crater, that was changed extensively by repeated flooding, slipping of ice, and collapses.[citation needed]


"Cantaloupe terrain"

The cantaloupe-skin terrain as seen from 130,000 km by Voyager 2.

Tano Sulci is one of the long faults that cross the strange region of Bubembe on Triton. This region is also known as "cantaloupe terrain" because of its resemblance to the skin of a cantaloupe. The origin of this region is unknown, but it could have been caused by diapirism (the rising and falling of frozen nitrogen or other ices), by collapses, and by flooding caused by cryovolcanism. Even though the terrain has few craters, it is believed that this is the oldest terrain on Triton. This terrain probably covers much of the northern hemisphere.[citation needed] Image File history File links Download high resolution version (1010x989, 113 KB) The Cataloupe terrain of Triton. ... Image File history File links Download high resolution version (1010x989, 113 KB) The Cataloupe terrain of Triton. ... Trinomial name Cucumis melo cantalupensis Cucumis melo reticulatus Naudin. ... Image of the south pole of Triton taken by Voyager 2 in 1989. ...


This cantaloupe terrain which is mostly dirty frozen water is known to exist only on Triton. It contains depressions that are 30-50 km in diameter. The depressions ("cavi") are probably not impact craters by meteorites because they are regular and have smooth curves. These depressions might have been caused by viscous ice eruptions. Standing on this point of the surface would resemble Earth's moon, but with less craters and boulders. Triton is geologically active; its surface is young and has relatively few impact craters. There are valleys and ridges that are very complex on the entire surface, probably the result of tectonism and icy volcanism. Volcanic activity could be related to tidal heating from when Triton was captured by Neptune, somewhat like the way volcanoes on Io are powered today.[6] This article is about volcanoes in geology. ... Atmospheric characteristics Atmospheric pressure trace Sulfur dioxide 90% Io (eye-oe, IPA: , Greek Ῑώ) is the innermost of the four Galilean moons of Jupiter. ...


Hili and Mahilani are two candidate cryovolcanoes that have been observed on Triton. They are named after a Zulu water sprite and a Tongan sea spirit, respectively.[7] Triton is then like the Earth, Io, Enceladus, and perhaps Venus and Titan, one of the few worlds of the solar system that have current volcanic activity.[8] Image of the south pole of Triton taken by Voyager 2 in 1989. ... Zulu mythology contains numerous deities, commonly associated with animals or general classes of natural phenomena. ... This article or section does not cite its references or sources. ... Atmospheric characteristics Atmospheric pressure trace Sulfur dioxide 90% Io (eye-oe, IPA: , Greek Ῑώ) is the innermost of the four Galilean moons of Jupiter. ... [5] Atmospheric characteristics Pressure trace, significant spatial variability [6], [7] Water vapour 91% [8] Carbon dioxide 3. ... Adjectives: Venusian or (rarely) Cytherean Atmosphere Surface pressure: 9. ... Titan (, from Ancient Greek Τῑτάν) or Saturn VI is the largest moon of Saturn and the second largest moon in the solar system,[4] after Jupiters moon Ganymede. ...


History of observation and exploration

William Lassell started making mirrors for his telescope in 1820, and produced better mirrors in 1844. When John Herschel received news of Neptune's discovery, he wrote to Lassell suggesting he search for moons. Lassell did so and discovered Triton just eight days later, on 10 October 1846,[9][10][11][12] only 17 days after the discovery of the planet itself. Lassell also claimed to have discovered rings. However, although Neptune does have rings, they are so faint and dark that what Lassell saw was probably an illusion.[13] William Lassell (June 18, 1799 – October 5, 1880) was a British astronomer, born in Bolton, Lancashire, England. ... John Herschel Sir John Frederick William Herschel (7 March 1792 – 11 May 1871) was an English mathematician and astronomer. ... October 10 is the 283rd day of the year (284th in leap years). ... 1846 was a common year starting on Thursday (see link for calendar). ...


The first detailed observations of the satellite were not made until 100 years after its discovery, when it was found to have a retrograde orbit around Neptune (i.e., it orbits in a direction opposite to the planet's rotation), which is at a very high angle of inclination to the plane of Neptune's orbit.


Even though the orbital properties of Triton had been defined almost correctly in the 19th century, little was known about Triton itself until Voyager 2 arrived at the end of the 20th century. The satellite appeared pink-yellowish in the first photograph taken.


Before the arrival of Voyager 2, it was suspected that Triton might have liquid nitrogen seas and a nitrogen/methane atmosphere with a density as much as ⅓ that of the Earth. Like the famous overestimates of the atmospheric density of Mars, this was found to be completely false, but like on Mars a denser early atmosphere is postulated.[14]


The first attempt to measure the diameter of Triton was made by Gerard Kuiper in 1954. He obtained a value of 3800 km. Various subsequent attempts to measure the diameter of the satellite arrived at values ranging from 2500 to 6000 km, or slightly smaller than our Moon to nearly half the diameter of Earth.[15] Gerard Kuiper, circa 1963. ...

Neptune and Triton three days after the flyby of Voyager 2.

Data from Voyager 2's approach to Neptune on August 25, 1989 enabled a more accurate estimate of Triton's diameter to be made (estimated at 2706 km).[16] Image File history File links Voyager_2_Neptune_and_Triton. ... Image File history File links Voyager_2_Neptune_and_Triton. ... August 25 is the 237th day of the year in the Gregorian calendar (238th in leap years), with 128 days remaining. ... 1989 (MCMLXXXIX) was a common year starting on Sunday of the Gregorian calendar. ...


In the 1990s, different observations from Earth were made of the limb of Triton using the occultation of stars by Triton. These observations indicated the presence of an atmosphere and an exotic surface. These observations suggest that the atmosphere is denser than was thought on the basis of the measurements made by Voyager 2.[17]


See also

This is a list of named geological features, of various kinds, on Triton. ...

References

  1. ^ Planetary Satellite Physical Parameters. Solar System Dynamics. Retrieved on 2006-05-10.
  2. ^ Flammarion, C. (1880). Astronomie populaire, p. 591. Retrieved on 2007-04-10.
  3. ^ Agnor, C. B.; and Hamilton, D. P. (2006). "Neptune's capture of its moon Triton in a binary–planet gravitational encounter". Nature 441: pp. 192–194. 
  4. ^ Chyba, C. F.; Jankowski, D. G.; and Nicholson, P. D. (1989). "Tidal evolution in the Neptune-Triton system". Astronomy and Astrophysics 219 (No. 1–2): pp. L23–L26. 
  5. ^ Elliot, J. L.; Hammel, H. B.; Wasserman, L. H.; Franz, O. G.; McDonald, S. W.; Person, M. J.; Olkin, C. B.; Dunham, E. W.; Spencer, J. R.; Stansberry, J. A.; Buie, M. W.; Pasachoff, J. M.; Babcock, B. A.; and McConnochie, T. H. (1998). "Global warming on Triton". Nature 393: pp. 765–767. DOI:10.1038/31651. 
  6. ^ http://jove.geol.niu.edu/faculty/stoddard/IO/iogrl2.htm Jove.geol.niu.edu Retrieved on 05-19-07
  7. ^ USGS Astrogeology Research Program: Gazetteer of Planetary Nomenclature, search for "Hili" and "Mahilani"
  8. ^ Kargel, J. S. (1994). "Cryovolcanism on the icy satellites". Earth, Moon, and Planet 67: pp. 101–113. DOI:10.1007/BF00613296. 
  9. ^ Lassell, W.; Discovery of Supposed Ring and Satellite of Neptune, Monthly Notices of the Royal Astronomical Society, Vol. 7, No. 9 (November 13, 1846), p. 157
  10. ^ Lassell, W.; Physical observations on Neptune Monthly Notices of the Royal Astronomical Society, Vol. 7, No. 10 (11 December 1846), pp. 167–168
  11. ^ Lassell, W.; Observations of Neptune and his satellite, Monthly Notices of the Royal Astronomical Society, Vol. 7, No. 17 (1847), pp. 307–308
  12. ^ Lassell, W.; Lassell's Satellite of Neptune, Monthly Notices of the Royal Astronomical Society, Vol. 8, No. 1 (November 12, 1847), p. 8
  13. ^ Smith, R. W.; and Baum, R. (1984). "William Lassell and the Ring of Neptune: A Case Study in Instrumental Failure". J. Hist. Astron. 15: pp. 1–17. 
  14. ^ Lunine, J. I.; and Nolan, Michael C. (1992). "A massive early atmosphere on Triton". Icarus 100: pp. 221–234. DOI:10.1016/0019-1035(92)90031-2. 
  15. ^ Cruikshank, D. P.; Stockton, A.; Dyck, H. M.; Becklin, E. E.; and Macy, W., Jr. (1979). "The diameter and reflectance of Triton". Icarus 40: pp. 104–114. DOI:10.1016/0019-1035(79)90057-5. 
  16. ^ Stone, E. C.; and Miner, E. D. (1989). "The Voyager 2 Encounter with the Neptunian System". Science 246: pp. 1417–1421.  And the following 12 articles pp. 1422–1501.
  17. ^ Savage, D.; Weaver, D.; and Halber, D.; Hubble Space Telescope Helps Find Evidence that Neptune's Largest Moon Is Warming Up, News Release Number: STScI-1998-23 (June 24, 1998)
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For the Manfred Mann album, see 2006 (album). ... May 10 is the 130th day of the year in the Gregorian calendar (131st in leap years). ... Year 1880 (MDCCCLXXX) was a leap year starting on Thursday (link will display the full calendar). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the CE era. ... April 10 is the 100th day of the year in the Gregorian calendar (101st in leap years). ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... November 13 is the 317th day of the year (318th in leap years) in the Gregorian calendar, with 48 days remaining. ... 1846 was a common year starting on Thursday (see link for calendar). ... December 11 is the 345th day (346th in leap years) of the year in the Gregorian calendar. ... 1846 was a common year starting on Thursday (see link for calendar). ... 1847 was a common year starting on Friday (see link for calendar). ... November 12 is the 316th day of the year (317th in leap years) in the Gregorian calendar, with 49 days remaining. ... 1847 was a common year starting on Friday (see link for calendar). ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... June 24 is the 175th day of the year (176th in leap years) in the Gregorian calendar, with 190 days remaining. ... 1998 (MCMXCVIII) was a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean [1]. // Coated in ice, power and telephone lines sag and often break, resulting in power outages. ... Neptune (top) and Triton (bottom), 3 days after the Voyager 2 flyby. ... Adjectives: Neptunian Atmosphere Surface pressure: ≫ 100 kPa (cloud level) Composition: 80% ± 3. ... A simulated view of Naiad orbiting Neptune with The Sun in the distance. ... A simulated view of Thalassa orbiting Neptune. ... A simulated view of Despina orbiting Neptune Despina (des-pee-na or des-pye-na; Latin DespÅ“na from Greek Δεσποίνη) is the third known moon of Neptune. ... A simulated view of Galatea orbiting Neptune Galatea (gal-a-tee-a, Greek Γαλατεία) is the fourth known moon of Neptune, named after Galatea, one of the Nereids of Greek legend. ... A simulated view of Larissa orbiting Neptune Larissa (la-ris-a, Greek Λάρῑσα) is the fifth of Neptunes known moons. ... Atmospheric pressure 0 kPa Proteus (proe-tee-us, Greek Πρωτέας) is one of Neptunes moons. ... Nereid (IPA: , IPA: , Greek Νηρηίδα), or Neptune II, is a moon of Neptune. ... Halimede is a retrograde irregular satellite of Neptune. ... Sao is a prograde irregular satellite of Neptune. ... Laomedeia, or Neptune XII, is a prograde irregular satellite of Neptune. ... Psamathe (sam-a-thee, Greek Ψαμαθεια, Latin PsamathÄ“) is an irregular natural satellite of Neptune. ... Neso, also known as Neptune XIII, is the outermost irregular natural satellite of Neptune. ... As of March 2007, there are five[1] known Neptune Trojans (named by analogy to the Trojan asteroids) which have the same orbital period as the planet. ... This is a list of the named rings and ring arcs of Neptune. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Major features of the Solar System (not to scale; from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth and its Moon, and Mars. ... Apparent magnitude: up to -12. ... The relative sizes of and distance between Mars, Phobos, and Deimos, to scale. ... Jupiters outer moons and their highly inclined orbits. ... The Saturnian system (photographic montage) Saturn has fifty-six confirmed natural satellites, plus three unconfirmed moons. ... Uranus has 27 known moons. ... Neptune (top) and Triton (bottom), 3 days after the Voyager 2 flyby. ... Image File history File links Download high resolution version (604x602, 23 KB)Cassini color image of Rhea taken Jan. ... The planet Pluto has three known moons. ... Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... 243 Ida and its moon Dactyl An asteroid moon is an asteroid that orbits another asteroid. ... This article or section does not adequately cite its references or sources. ... Titan (, from Ancient Greek Τῑτάν) or Saturn VI is the largest moon of Saturn and the second largest moon in the solar system,[4] after Jupiters moon Ganymede. ... There is also an asteroid named 204 Kallisto. ... Atmospheric characteristics Atmospheric pressure trace Sulfur dioxide 90% Io (eye-oe, IPA: , Greek Ῑώ) is the innermost of the four Galilean moons of Jupiter. ... Apparent magnitude: up to -12. ... Apparent magnitude: 5. ... Atmospheric pressure   Titania (ti-taan-ee-É™ or tye-tan-ee-É™) is the largest moon of Uranus. ... Atmosphere none Rhea (ree-a, Greek ‘Ρέα) is the second largest moon of Saturn and was discovered in 1672 by Giovanni Domenico Cassini. ... Atmospheric pressure 0 kPa Oberon (oe-bur-on) is the outermost of the major moons of the planet Uranus. ... Iapetus (eye-ap-É™-tÉ™s, IPA , Greek Ιαπετός) is the third-largest moon of Saturn, discovered by Giovanni Domenico Cassini in 1671. ... Charon (shair-É™n or kair-É™n (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... Atmospheric pressure 0 kPa Umbriel (um-bree-É™l, IPA ) is a moon of Uranus discovered on 1851-10-24 by William Lassell. ... Atmospheric pressure 0 kPa Ariel (air-ee-É™l, IPA ) is a moon of Uranus discovered on 24 October 1851 by William Lassell. ... Atmosphere none Dione (dye-oe-nee, Greek Διώνη) is a moon of Saturn discovered by Giovanni Cassini in 1684. ... Atmosphere none Tethys (tee-thÉ™s or teth-É™s, IPA , Greek Τηθύς) is a moon of Saturn that was discovered by Giovanni Domenico Cassini in 1684. ... [5] Atmospheric characteristics Pressure trace, significant spatial variability [6], [7] Water vapour 91% [8] Carbon dioxide 3. ... Miranda (IPA: ) is the smallest and innermost of Uranus major moons. ... Atmospheric pressure 0 kPa Proteus (proe-tee-us, Greek Πρωτέας) is one of Neptunes moons. ... Mimas (mee-mÉ™s or mye-mÉ™s, IPA: , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. ... In astronomy, an inner satellite is a natural satellite following a prograde, low inclination orbit inwards of the large satellites of the parent planet. ... A Trojan moon is a natural satellite of a planet occupying the L4 or L5 equilateral Lagrangian points of a primary-moon system. ... In astronomy, an irregular satellite is a natural satellite following a distant, inclined, often retrograde orbit and believed to be captured as opposed to a regular satellite, formed in situ. ... This is a list of natural satellites in the solar system: Mercury: none Venus: none Earth: Moon Mars: Phobos Deimos Jupiter: see Jupiters natural satellites Saturn: see Saturns natural satellites Uranus: see Uranus natural satellites Neptune: see Neptunes natural satellites Pluto: Charon In addition, various asteroids are... This is a list of natural satellites in the solar system, ordered from largest to smallest by average diameter. ... This timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. ... The naming of natural satellites has been the responsibility of the IAUs committee for Planetary System Nomenclature since 1973. ... Major features of the Solar System (not to scale; from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth and its Moon, and Mars. ... The Sun (Latin: Sol) is the star at the center of the Solar System. ... This article is about the planet. ... Adjectives: Venusian or (rarely) Cytherean Atmosphere Surface pressure: 9. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... Spectral type: G[8] Absolute magnitude: 3. ... Adjectives: Jovian Atmosphere Surface pressure: 20–200 kPa[4] (cloud layer) Composition: ~86% H2 ~13% Helium 0. ... Adjectives: Saturnian Atmosphere Surface pressure: 140 kPa Composition: >93% hydrogen >5% helium 0. ... Adjectives: Uranian Atmosphere Surface pressure: 120 kPa (at the cloud level) Composition: 83% Hydrogen 15% Helium 1. ... Adjectives: Neptunian Atmosphere Surface pressure: ≫ 100 kPa (cloud level) Composition: 80% ± 3. ... Adjectives: Plutonian Atmosphere Surface pressure: 0. ... Absolute magnitude: −1. ... The eight planets and three dwarf planets of the Solar System. ... Artists impression of Pluto (background) and Charon (foreground). ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Apparent magnitude: up to -12. ... The relative sizes of and distance between Mars, Phobos, and Deimos, to scale. ... 243 Ida and its moon Dactyl An asteroid moon is an asteroid that orbits another asteroid. ... Jupiters outer moons and their highly inclined orbits. ... The Saturnian system (photographic montage) Saturn has fifty-six confirmed natural satellites, plus three unconfirmed moons. ... Uranus has 27 known moons. ... Neptune (top) and Triton (bottom), 3 days after the Voyager 2 flyby. ... The planet Pluto has three known moons. ... Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... A Small Solar System Body (SSSB) is a term defined in 2006 by the International Astronomical Union to describe objects in the Solar System that are neither planets nor dwarf planets: [1] This encompasses: all minor planets apart from the dwarf planets, : the classical asteroids, (except for 1 Ceres, the... It has been suggested that micrometeoroid be merged into this article or section. ... It has been suggested that minor planet be merged into this article or section. ... For details on the physical properties of bodies in the asteroid belt see Asteroid and Main-belt comet. ... The centaurs are a class of icy planetoids that orbit the Sun between Jupiter and Neptune, named after the mythical race of centaurs. ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ... Comet Hale-Bopp Comet McNaught as seen from Swifts Creek, Victoria, Australia on 23 January 2007 For other uses, see Comet (disambiguation). ... This image is an artists rendering of the Oort cloud and the Kuiper Belt. ... See also Lists of astronomical objects Category: ... Below is a list of solar system objects with diameter >500km: The Sun, a spectral class G2 star Mercury Venus Earth Moon Mars Jupiter Io Europa Ganymede Callisto complete list of Jupiters natural satellites Saturn Tethys Dione Rhea Titan Iapetus complete list of Saturns natural satellites Uranus Ariel... This is a list of solar system objects by radius, arranged in descending order of mean volumetric radius. ... This is a list of Solar system objects by mass, in decreasing order. ...


  Results from FactBites:
 
Neptune's Moon Triton (1455 words)
Triton [TRY-tun] is the largest moon of Neptune, with a diameter of 2,700 kilometers (1,680 miles).
With Triton's long seasons, the southern summer has been progressing, and the south pole has received increasing sunlight; thus, it is probable that much of the frost covering the region in 1989 has evaporated, some of which may have condensed at the equator (hence the bright region there).
Triton's surface is mostly covered by nitrogen frost mixed with traces of condensed methane, carbon dioxide, and carbon monoxide.
Triton (208 words)
Of the 8 moons, it is the 2nd farthest from Neptune, with a standoff distance of 354,800 km.
Triton may be one of the largest of the icy moons, is comparable to Europa, with a diameter of 2700 km (1800 miles).
Triton is very interesting, it has a unique and fascinating surface, and is one of the few moons with the possibility for a weak atmosphere and an environment suitable for life.
  More results at FactBites »

 
 

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