Formation and evolution of the Solar System timescale of their formation. At the current locations it would have taken millions of years for their cores to accrete. This means that Uranus and Neptune may have formed closer to the Sun—near or even between Jupiter and Saturn—and later migrated or were ejected outward (see Planetary migration below). Motion in the planetesimal era was not all inward toward the Sun; the "Stardust" sample return from Comet Wild 2 has suggested that materials from the early formation of the Solar System migrated from the warmer inner Solar System to the region of the Kuiper belt. After between three and ten
Solar eclipses on Jupiter the variations were caused by the varying distance between Earth and Jupiter as the two planets moved in their orbits around the Sun. Spacecraft can be used to observe the solar eclipses on Jupiter; these include "Pioneer 10" and "Pioneer 11" (1973 and 1974), "Voyager 1" and "Voyager 2" (1979), "Galileo" orbiter (1995–2003), "Cassini–Huygens" (2000) and "New Horizons" (2007) observed the transits of their moons and its shadows. The mean angular diameter of the Sun as viewed from Jupiter is 372 arc-seconds, or 6' 12" (about that of the Sun as viewed from Earth), varying slightly from 381" at perihelion