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Astronomy: Neptune
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German astronomers Johann Galle and Heinrich D'Arrest discovered Neptune on 23 September 1846 using the calculations of Urbain Le Verrier. In 1845 John Couch Adams began to analyze the motion of Uranus, who was beaten by Verrier who published his conclusions in 1846. Today both Adams and Verrier are honoured to have discovered the planet, although Galle and D'Arrest were the first to see it. Under good conditions Uranus can be seen with the human eye, but Neptune is too dim to be seen without a telescope or a pair of binoculars. Before Voyager 2 arrived at Neptune the only known satellites were Triton and Nereid. In August 1989 this Voyager spacecraft revealed another six moons. And it confirmed that the gas planet has immature rings: 3 thin rings and a broad dusty belt. Planet compositionNeptune orbits the Sun once in 165 years. Its size is about one third of Jupiter.Neptune is mostly composed of liquid water, methane and ammonia. It is the most dense of the Jovian planets. The thick gas atmosphere consits mostly of hydrogen and helium. Neptune's blue color comes from small amounts of methane which absorbs red light. The axis of rotation for Neptune is tilded 28o. The magnetic field is tilded about 47o from the rotational axis. This big tilded field can't be explained with the current information we have (just like with Uranus). Giant windsClouds are present and visible. Careful tracking showed that the winds are the fastest in our solar system reaching speeds of 2000 kilometers per hour at the equator.Different types of clouds were discovered by Voyager 2. The Great Dark Spot was a prominent atmospheric storm 12.000 kilometers wide (the size of Earth). Another but smaller Dark Spot could also be found on the Southern hemisphere. Storms on Neptune seem to originate from the equator region and dissolve when moving to the poles. The Great Dark Spot was comparable to the Great Red Spot of Jupiter. |
 The Great Dark Spot and a smaller spot (storm) on Neptune. After years the Great Dark Spot has dissolved, but other storms have emerged. < JPG image 529 X 765 pixels > |
Life on Triton?The moon Triton is unlike any other moon we know. The moon revolves around Neptune in a retrogade motion (backwards compared to Neptune's rotation). Analysis has shown that the moon is in a decaying orbit and is slowly being pulled to the planet. This orbit strongly suggests that the satellite was formed elsewhere and captured by Neptune.Interestingly Triton and Pluto have similarities, including size, mass and probably also in their composition. It's thought that Triton - like Pluto - is a former Edgeworth-Kuiper Belt object. The surface is composed of methane, nitrogen ice and frost. Some surface areas are yellowish to peach colored, possibly representing methane and nitrogen ices that have been converted to complex organic compounds by cosmic rays and ultraviolet radiation from the Sun. Like Jupiters moon Io, Triton also has active eruptions. The dark geysers rise to an altitude of 8 kilometers above the surface. Related subjects>> Voyager>> Io >> Uranus >> Pluto >> Edgeworth-Kuiper Belt |
 Stunning picture of the moon Triton < JPG image 751 X 828 pixels > |
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