The existence of Neptune, outermost of the giant gaseous planets, was predicted before it was actually discovered. Telescopic observations of Uranus in the early 1800s showed notable discrepancies between its predicted position in orbit and where it was actually observed. Independently of each other, two mathematicians, John Couch Adams of Cambridge, England and the Frenchman Urbain John-Joseph Le Verrier, analyzed the problem and suggested both the position and the mass of an as-then unknown planet to account for the abnormal motions of Uranus.
KeywordsRing Material Outer Planet Basaltic Maria Telescopic Observation Dark Streak
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