- located at a distance of 2.1 to 3.3 Astronomical Unit (AU) from the Sun and contains many thousands of objects, of which some 30,000 have individually identified.
- scientists believe that the main belt asteroids are planetismals left over from the formation of the Solar System to prevent from clumping together into a rock planet by the gravity of massive gas planet Jupiter.
- only one of the main asteroid belt – (4) Vesta, is bright enough to be seen with the unaided eye (naked-eye).
- Ida is one of the asteroids photographed by the Galileo Spaceprobe – it has an irregular shape (35 x 15 x 13 miles), and is the only asteroid known to have its own natural satellite, Dactlyl. Â (photo)
- tiny asteroid – Dactyl measures just 0.6 miles in diameter and orbits Ida at a distance around 60 miles.
- NEAR – Near Earth Asteroid Rendezvous, targeted two other asteroids; (252) Mathilde and (433) Eros. The spacecraft surveyed both asteroids from orbit before landing on the surface of Mathilde in 2011. (diagram)
- located at the outer edge of the main belt in two groups that are at 60 degrees to both the Sun and Jupiter. (diagram)
- the first Trojan to be discovered was named Achilles in 1906 – many Trojan asteroids are named after warrior s from the ancient Greek tales of the Trojan wars.
- in addition to the Trojans; some other asteroids also orbit in groups that are known as Hirayama families.
- these groups are believed to be the remnants of larger asteroids that were smashed to pieces by collisions. (diagram)
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