The Solar System


What is a moon?

A moon is a natural satellite that orbits a planet. As with planets, it is sometimes hard to know exactly what status a moon has. For example, whereas many moons (such as Earth’s Moon) formed at about the same time as the planets they orbit, many other moons probably formed as independent objects that were then captured in a planet’s gravitational field.


This is a web preview of the "The Handy Astronomy Answer Book" app. Many features only work on your mobile device. If you like what you see, we hope you will consider buying. Get the App