Geology of solar terrestrial planets approaching Ceres at aphelion, which may constrain Dawn's ability to observe this phenomenon. Note: This info was taken directly from the main article, sources for the material are included there. Asteroids, comets, and meteoroids are all debris remaining from the nebula in which the Solar System formed 4.6 billion years ago. The asteroid belt is located between Mars and Jupiter. It is made of thousands of rocky planetesimals from to a few meters across. These are thought to be debris of the formation of the Solar System that could not form a planet due to Jupiter's gravity. When asteroids collide
Solar System icy objects. Astronomers sometimes informally divide this structure into separate regions. The inner Solar System includes the four terrestrial planets and the asteroid belt. The outer Solar System is beyond the asteroids, including the four giant planets. Since the discovery of the Kuiper belt, the outermost parts of the Solar System are considered a distinct region consisting of the objects beyond Neptune. Most of the planets in the Solar System have secondary systems of their own, being orbited by planetary objects called natural satellites, or moons (two of which, Titan and Ganymede, are larger than the planet Mercury), and, in