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Belt
Asteroid Belt
Between Mars and Jupiter, millions of chunks of rock fly around the Sun: the Asteroid Belt. They were left over when the planets formed. Even so, there is a great deal of empty space there.
Fact file
- Type
- Belt
- Distance from the Sun
- 400,000,000 km
- Orbital period
- 4.6 years
- Temperature
- -108 °C on average (from -145 to -70 °C)
Interesting facts about the Asteroid Belt
- The Asteroid Belt lies between Mars and Jupiter (2.2 to 3.2 AU) and contains more than a million asteroids larger than 1 km.
- Despite all those lumps of rock it is almost empty: together they weigh only about 4% of the Moon's mass, and two asteroids are on average more than a million kilometres apart – space probes fly through safely.
- It is not a destroyed planet, but material that could never clump together into a planet because of Jupiter's gravity.
Formation
When the Solar System was forming, Jupiter's strong gravity disturbed the material between Mars and Jupiter: the lumps collided too fast and shattered instead of merging. What remained was a belt of primordial material.
Composition
The individual bodies have no atmosphere to speak of.
Exploration
Dawn studied the asteroid Vesta in 2011-2012 and Ceres in 2015-2018. Lucy (since 2021) and Psyche (launched 2023, arrival 2029) are exploring further asteroids; NEAR visited the near-Earth asteroid Eros back in 2000/01.
In comparison
The whole belt contains less mass than our Moon, spread over a space larger than Earth's orbit.
Test your knowledge of the Asteroid Belt
Where is the Asteroid Belt?
Between Mars and Jupiter. Jupiter's gravity prevented a planet from forming there.
The full quiz with points and badges is in the 3D model under “Explore”.
The Asteroid Belt in the tours
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