Asteroids

Did you know that rocky leftovers from the solar system’s formation still orbit the Sun? These are called asteroids, and they orbit the Sun just like planets.

Asteroids are small, rocky bodies without enough gravity to make them round. Unlike planets, they have no atmosphere or heat inside them.

Most of these are found in the asteroid belt between Mars and Jupiter. Jupiter’s strong gravity prevents these rocks from merging to form a planet.

Even though the asteroid belt contains thousands of asteroids, their total mass is only about 4% of the Moon’s mass.

Some asteroids, called near-Earth asteroids, follow paths that bring them close to or across Earth's orbit. While smaller ones usually break apart in the atmosphere, larger ones can result in significant impacts, like the events that caused mass extinctions in Earth's history.

Scientists study asteroids because they are unchanged residues of the early solar system, preserving clues about the solar system’s formation.

Space missions like Hayabusa and Dawn have explored asteroids and returned samples, revealing their structure, history, and the building blocks of planets.