• episode “#20” • Crash Course Astronomy
Now that we’ve finished our tour of the planets, we’re headed back to the asteroid belt. Asteroids are chunks of rock, metal, or both that were once part of smallish planets but were destroyed after collisions. Most orbit the Sun between Mars and Jupiter, but some get near the Earth. The biggest, Ceres, is far smaller than the Moon but still big enough to be round and has undergone differentiation.
