Artificial gravity is a way to make it feel like you are on Earth while you are in space. It works by having a spacecraft that is spinning around really fast. When something is spinning around, it creates gravity. It's like when you are on a playground merry-go-round and you spin around quickly - the thing pushing out against your body is the artificial gravity. Astronauts in the spacecraft will feel like they are standing on the ground, even though they are really in space.