The main asteroid belt, situated in the broad region betweeen the orbits of Mars and Jupiter, contains countless rocky bodies (white points in diagram). The Trojan asteroids (pink) can survive outside this belt because they are locked in a 1:1 orbital resonance with Jupiter, which keeps them spaced safely about 60 degrees ahead or behind that giant planet in its orbit. For clarity, only asteroids larger than about 50 kilometers are plotted here. A space-probe image of the near-Earth asteroid Eros (above) gives a sense of what most asteroids probably look like. Eros is about 30 kilometers long, much too small for its gravity to make it spherical. (Diagram courtesy of the Minor Planet Center; image courtesy of NASA/Johns Hopkins University
Applied Physics Laboratory.) |
