Science
What is an asteroid?
An asteroid is a rocky leftover from the early solar system, too small to be a planet. Most orbit the Sun in a belt between Mars and Jupiter, ranging from tiny boulders to bodies hundreds of kilometers across.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains an asteroid.
Key things to understand
- 1It's a rocky or metallic object orbiting the Sun.
- 2Most lie in the asteroid belt between Mars and Jupiter.
- 3They're leftovers from the solar system's formation.
- 4Sizes range from pebbles to hundreds of kilometers wide.
- 5A large impact is thought to have wiped out the dinosaurs.
Frequently asked questions
- What's the difference between an asteroid and a comet?
- Asteroids are rocky and mostly stay in the inner solar system; comets are icy, come from farther out, and grow tails near the Sun.
- Where are most asteroids?
- In the asteroid belt, a ring of rocky bodies orbiting the Sun between Mars and Jupiter.
- Could an asteroid hit Earth?
- Large impacts are rare but possible; agencies track near-Earth asteroids and study ways to deflect a dangerous one.