Asteroids, comets, + meteorites are scraps left over from formation of solar system (s. s. ) gives understanding of how planets + larger moons came to exist. Asteroids are planetesimals left over from birth of solar system. Meteorites: pieces of rock that have fallen to ground from space. Most meteorites = pieces of asteroids that orbited sun for billions of yrs bef. falling to. Asteroid"s orbit calculated by law of gravity (section 4. 4). Ceres: largest asteroid in ss (under 1000km in diameter). Probably more than a million asteroids w/ diameters > 1 km. If all asteroids compressed together + compressed into sphere by gravity then = object < If asteroid is relatively large, gravity can mold its solid rock into spherical or near- spherical shape. *only ceres is large enough for gravity to have compressed it into roughly spherical shape thus ceres is qualified as dwarf planet.