Hold the asteroid belt in the palm of your hand. The shape of this model is defined by the orbits of the 50 largest asteroids in our solar system. The thickness of each orbit in the model is proportional to the size of the asteroid it represents. The largest asteroid in the model (the thickest path, at an angle to most others) is the dwarf planet Ceres, which makes up about 30% of the mass of the asteroid belt. Asteroid belt data comes from a high precision NASA funded database put together by the Lowell Observatory: ftp://ftp.lowell.edu/pub/elgb/astorb.html.