This coming weekend I'm helping with a moon activity for ASRAS' Young Astronomers Program, so I thought I'd talk a bit about moons in our solar system this week.
We've all looked up at night and seen our big, bright, shiny moon glaring back at us. The moon actually doesn't shine at all. It only looks bright because it's reflecting light from the Sun! Earth is not the only planet with a moon. Most of the other planets in our solar system have moons, and some even have multiple moons! A moon (or natural satellite as astronomers often call the moons of other planets) is loosely defined as an object that is gravitationally bound to and orbiting a planet. Below is a list of each planet and the number of moons it has.
Mercury: 0
Venus: 0
Earth: 1
Mars: 2
Jupiter: 63
Saturn: 47
Uranus: 27
Neptune: 13
Moons come in all shapes and sizes, and most don't look anything like our moon! They don't have to be round white objects made of sand and rock. Some moons are made of metal while others some sort of liquid. Jupiter's moon Io even has erupting volcanoes on it! The picture below shows some of the more popular and well known moons in our solar system to scale so you can see how other planets moons size up to ours!
(Phobos, Dactyl and Deimos are there, they are just very tiny in comparison!)
Image credit: NASA
