In the solar system, nothing stands still—not even you.
You and everything else on Earth are traveling up to 1,000 miles per hour right now! That’s how fast the planet’s surface is spinning, or rotating, at the equator. Other planets and moons spin, too, and even the Sun itself spins.
While these objects rotate, they revolve around, or orbit, each other. The Moon orbits Earth. Earth orbits the Sun, and so do other planets, their moons, and asteroids.
Sometimes these spinning, circling, moving objects crash into one another. Comets fall into planets, and asteroids smash into moons. Why don’t all these planets, moons, and asteroids just stay where they are? The answer is gravity. All objects pull other objects toward them, and the more mass (or matter) an object has, the stronger its pull.
The Sun has 99.9 percent of all the matter in the solar system. Everything else makes up just 0.1 percent. So the Sun is the most massive thing in the neighborhood. Its pull is so strong that it can even “grab” comets millions of miles away. The Sun’s gravity holds this solar system together and, in fact, it’s the reason we even have a solar system.
