Comets and asteroids are leftovers from when the 9 planets formed in the solar system, 4.6 billion years ago. Comets are fragile balls of snow and dust found at the edge of the solar system in oort cloud. ( It is a cloud surrounding solar system, made up 10 trillion comets ) Some leave the cloud and travel towards the sun. Suns heat melts the snow and comets appear to grow in size many times over.

The comets are usually named after their discoverer, the english scientiest Edmund Hailey.

Asteroids are made up of rocks and found mainly between the orbits of mars and jupiter. Between the orbits of mars and jupiter is the asteroid belt, a doughnut shaped ring made up millions of asteroids pieces of rocks and metal. The smallest are specks of dust ( the biggest is ceres, is more than 900 kms across ). Not all the asteriods are in the asteroid belt. About 10% travel in groups away from the belt.

The tiny pieces of dust and chunks of rock travel through the space, they are meteroites and originate from two main sources: Comets and Asteriods. About 2,20,000 tonnes of such material enter earth every year. The smallest meteroites, produce meteors ( tiny meteroites which burn up as they reach the earths atmosphere producing streaks of light called meteors )