Book 8, Question 68
Why Is the Asteroid Belt Between Mars and Jupiter?
The asteroid belt sits between Mars and Jupiter because leftover rocky pieces there never grew into a full planet. Jupiter's strong gravity stirred the region and kept them apart. Today they orbit as a scattered crowd of rocks.
More fun facts
- Most asteroids orbit the Sun in the main belt between Mars and Jupiter, moving the same direction as the planets.
- The belt holds an estimated 1.1 to 1.9 million asteroids wider than 1 kilometer, plus millions of smaller ones.
- Jupiter's powerful gravity can change the orbits of asteroids.
- There are nearly empty lanes in the belt, called Kirkwood gaps, where an asteroid's trip around the Sun would line up neatly with Jupiter's.
- Groups of asteroids called Trojans travel ahead of and behind Jupiter in its orbit.
- Ceres, the biggest object in the main belt, is a dwarf planet.
Sources: NASA Science, NASA Science, NASA Science
Questions kids ask
How many asteroids are in the main belt?
Over a million wider than 1 kilometer, and millions of smaller ones.