On March 29, 1807, the German astronomer Heinrich Olbers discovered the asteroid Vesta. Vesta is the second-largest body in the asteroid belt and is surpassed in size only by the dwarf planet Ceres. To look for asteroids, astronomers would draw sky charts every night and look for spots that moved. Sunlight reflecting off the asteroids can make them look like faint stars, but unlike stars, the asteroids didn't have a fixed location in the sky. Vesta was the fourth object to be discovered in the region between Mars and Jupiter, which we now know as the asteroid belt. Olbers and other astronomers thought the asteroid belt might be the remains of a hypothetical planet that was either smashed to pieces by a collision or ripped apart by Jupiter's gravity.