and the galaxy hurtling through space. The dots moving across the right side of the animation show how quickly each object travels 150 kilometers. As you can see, Earth's rotation is relatively ...

This has enabled us to make an attempt at mapping the planet over the last 40% of its history, which you can see in the ...

The moon is slowly moving away from us. About 4.5 billion years ago, a Mars-sized object (or perhaps a series of many smaller objects) crashed into Earth, sending bits of Earth's crust into space.