On Earth, you can look up at night and see the Moon shining bright from hundreds of thousands of miles away. But if you went to Venus, that wouldn’t be the case. Not every planet has a moon – so why do some planets have several moons, while others have none?
I’m a physics instructor who has followed the current theories that describe why some planets have moons and some don’t.
First, a moon is called a natural satellite. Astronomers refer to satellites as objects in space that orbit larger bodies. Since a moon isn’t human-made, it’s a natural satellite.
Currently, there are two main theories for why some planets have moons. Moons are either gravitationally captured if they are within what’s called a planet’s Hill sphere radius, or they’re formed along with a solar system.
