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
IAU definition of planet planets. Mike Brown, the discoverer of Sedna and Eris, has said that at least 53 known bodies in the Solar System probably fit the definition, and that a complete survey would probably reveal more than 200. The definition would have considered a pair of objects to be a double planet system if each component independently satisfied the planetary criteria and the common center of gravity of the system (known as the "barycenter") was located outside of both bodies. Pluto and Charon would have been the only known double planet in the Solar System. Other planetary satellites (like Earth and its