Solar System their mass, orbit, and distance from the Sun, with a possibly significant contribution from comets. The Sun, which comprises nearly all the matter in the Solar System, is composed of roughly 98% hydrogen and helium. Jupiter and Saturn, which comprise nearly all the remaining matter, are also primarily composed of hydrogen and helium. A composition gradient exists in the Solar System, created by heat and light pressure from the Sun; those objects closer to the Sun, which are more affected by heat and light pressure, are composed of elements with high melting points. Objects farther from the Sun are composed
Formation and evolution of the Solar System further hypothesized that the Mars-sized object may have formed at one of the stable Earth–Sun Lagrangian points (either or ) and drifted from its position. The moons of trans-Neptunian objects Pluto (Charon) and Orcus (Vanth) may also have formed by means of a large collision: the Pluto–Charon, Orcus–Vanth and Earth–Moon systems are unusual in the Solar System in that the satellite's mass is at least 1% that of the larger body. Astronomers estimate that the Solar System as we know it will not change drastically until the Sun has fused almost all the hydrogen fuel in its core into helium,