In astronomy, there are between 1.5 and 2 million small bodies known as asteroids that are a kilometer or larger in size. If you include smaller sizes, that number can jump to tens of billions. Although they are primarily found between the orbits of Mars and Jupiter, some (such as Chiron, which is between the orbits of Saturn and Uranus) are outside of that range. In astrology, there are four asteroids that are commonly used: Ceres, Juno, Pallas, and Vesta. These are also known as minor planets.

In 1982, a massive joke was played on the astrological community by Batya Stark and Mark Pottenger when they published The Asteroid Ephemeris, a book that supposedly delineated the asteroids Dudu, Dembowska, Pittsburg, and Frigga. Some people believed this to be valid, and have requested updates to this ephemeris from the publisher.