asteroid - any of numerous small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter)Ceres - the largest asteroid and the first discovered Pallas - a large asteroid; the second asteroid to be discovered planet - any of the celestial bodies (other than comets or satellites) that revolve around the sun in the solar system solar system - the sun with the celestial bodies that revolve around it in its gravitational field Vesta - the brightest asteroid but the fourth to be discovered |