Retrograde and prograde motion sky to temporarily reverse. The rotations of Earth and Mars are also affected by tidal forces with the Sun, but they have not reached an equilibrium state like Mercury and Venus because they are further out from the Sun where tidal forces are weaker. The gas giants of the Solar System are too massive and too far from the Sun for tidal forces to slow down their rotations. All known dwarf planets and dwarf planet candidates have prograde orbits around the Sun, but some have retrograde rotation. Pluto has retrograde rotation; its axial tilt is approximately 120 degrees. Pluto and
History of Solar System formation and evolution hypotheses itself. Most of the mass collected in the centre, forming the Sun; the rest of the mass flattened into a protoplanetary disc, out of which the planets and other bodies in the Solar System formed. There are, however, arguments against this hypothesis. French philosopher and mathematician René Descartes was the first to propose a model for the origin of the Solar System in his "Le Monde" (ou Traité de lumière) which he wrote in 1632 and 1633 and for which he delayed publication because of the Inquisition and it was published only after his death in 1664. In his view,