Triton (the moon)
See also: Triton
|- | bgcolor=" #000000" colspan=" 2" align=" center" | Triton seen by Travelling 2 on August 25th, 1989. Source: NASA |- | bgcolor=" #6295da" colspan=" 2" align=" center" | Discovered |- | Discovered by || William Lassell |- | Discovered in || October 10th 1846 |- | bgcolor=" #6295da" colspan=" 2" align=" center" | Orbital characteristics |- | Equatorial radius || 354.800 km |- | orbital Eccentricity || 0,0000 |- | orbital Period || 5,877 D |- | Slope || 156,834° |- | Natural satellite of || Neptune |- | bgcolor=" #ffc0c0" colspan=" 2" align=" center" | Physical characteristics |- | Diameter || 2706,8 km |- | Mass || 2,140×1022 kg |- | Density average || 2,1 G /cm ³ |- | Gravity of surface || 0,78 m/s2 |- | Escape velocity || 1,5 km/s |- | sidereal Day || synchronous |- | Albedo || 0,76 |- | Temperature on the surface || 34,5 K |- | bgcolor=" #6295da" colspan=" 2" align=" center" | Characteristics of the atmosphere |- | Atmospheric pressure || 0,001 kPa |} Triton (NR I Triton) is the seventh and larger satellites of Neptune. William Lassell discovered it in 1846, 17 days only after Neptune. It bears the name of Triton, god of the Greek Mythologie.
Orbits
Its orbit Rétrograde (it orbits in the direction opposed to that of the rotation of its planet) leaves think that Triton is an external body, probably originating in the Ceinture of Kuiper which was captured by Neptune. Because of this retrograde movement, the orbit of Triton is degraded slowly under the effect of the interactions of tide with Neptune.This case of figure is not strictly speaking, exceptional in the Solar system, thus the moons external of Jupiter (whose principal ones are Ananké, Carmé, Pasiphaé and Sinopé) and those of Saturn (whose Phœbé is the principal one) have also a retrograde orbit, but all those have less than 10% of the diameter of Triton, which thus remains an exceptional case because of its mass.
The moons which have a retrograde orbit cannot be formed in the same area of the solar Nébuleuse primitive as the planets around of which they turn: they are thus the captured moons.
The capture of Triton could have provided the contribution of heat necessary to melt the interior of Triton (the heating by the Forces of tide created by the circularization of a very eccentric orbit of capture could have kept liquid Triton during a billion years).
Slope
The slope of the orbit of Triton makes so that, while Neptune turns around the sun, the polar regions of Triton arise turn-with-turn towards the sun to 82 years of interval, undoubtedly producing extraordinarily marked climate changes. When Voyager 2 approached Triton in 1989, its south pole was turned towards the sun. Almost all the southern hemisphere is covered with a “glacier” of Azote and solid Méthane.
Composition
Triton has a density of 2,0×10 ³ kg/m ³ and comprises probably approximately water 25% in the form of ice (the remainder being rocks).
Atmosphere
It has a thin atmosphere of nitrogen with methane traces for an atmospheric pressure of about one hundred-millionth of atmosphere.
Surface
The temperature of surface of Triton is only 34,5 K, as low as on Pluton. However, Triton geologically remains active. Its surface is recent and present few crater S and Voyager 2 observed several Cryovolcan S producing of the jets of liquid nitrogen, dust or methane (with a height being able to reach 8 km). The volcanic activity is undoubtedly fed by the seasonal variations of temperature (contrary to the forces of tide of Io). Major faults (sulci) and valleys form complexes networks on the surface of Triton. They undoubtedly come from the successions of gel and thaws.The remarkable formations of surface were named according to the gods and watery spirits of various mythologies.
See too
External bond
Triton- Triton, on the site Nine planets
Simple: Triton (moon) Zh-classical: 海衛一
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