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
Timeline of discovery of Solar System planets and their moons Jupiter using numbers while the names suggested by his rival Simon Marius gradually gained universal acceptance. The International Astronomical Union (IAU) eventually started officially approving names in the late 1970s.</onlyinclude> In the following tables, planetary satellites are indicated in bold type (e.g. Moon) while planets and dwarf planets, which directly circle the Sun, are in italic type (e.g. "Earth"). The Sun itself is indicated in roman type. The tables are sorted by publication/announcement date. Dates are annotated with the following symbols: In a few cases, the date is uncertain and is then marked "(?)". "* Note: Moons marked by an