Asteroids are small rocky objects that orbit the sun just like the planets.That is also the reason they are called minor planets.The largest concentraction of these Asteroids is found between Mars and Jupitor. This region of space between these two planets is called the Main Asteriod Belt. There are more than a million Asteroids in this belt.The size of these asteroids varies from 500 km in diameter to around 30 feet in diameter. There are two more classifications of Asteroid belts called the Trojan and the Near Earth Asteroids