History of Solar System formation and evolution hypotheses is captured by the Sun and planets form from it. In this there were 6 original planets, corresponding to 6 point-masses in the filament, with planets A and B, the 2 innermost, colliding, the former at twice the mass of Neptune, and ejecting out of the Solar System, and the latter at 1/3 the mass of Uranus, and splitting into Earth and Venus. Mars and the Moon are former moons of A. Mercury is either a fragment of B or an escaped moon of A. The collision also produced the asteroid belt and the comets. T.J.J. See was an American
Uranus and visible wavelengths, Uranus's atmosphere is bland in comparison to the other giant planets, even to Neptune, which it otherwise closely resembles. When "Voyager 2" flew by Uranus in 1986, it observed a total of ten cloud features across the entire planet. One proposed explanation for this dearth of features is that Uranus's internal heat appears markedly lower than that of the other giant planets. The lowest temperature recorded in Uranus's tropopause is , making Uranus the coldest planet in the Solar System. In 1986, "Voyager 2" found that the visible southern hemisphere of Uranus can be subdivided into two