- What are comets?
They have elliptical orbits, which means that they get very close to the sun before swinging off into space.
Comets are made up of three very distinct parts: A nucleus, a tail and a coma. The nucleus is a solid core and that develops a coma that can have multiple tails when the comet gets close to the sun, and in fact are only present when it is near to the sun. The coma can be recognized because it is a fuzzy, dust cloud around the nucleus.
- How did comets come into being?
Because it was so fast not all of the material that was in it fell to the core; instead this material spread out until it looked like a flat disc. While this was happening the temperature in the center of the cloud was getting hotter, until it ignited through nuclear fusion and became the sun.
The outside of the disc, however was still cool and the water it contained began to freeze onto grains of dust, which became clumps, which in turn began to merge and eventually became planets.
Within the last ten years, scientists have discovered smaller clumps left over from this activity called planetesimals beyond Neptune. These make up an asteroid belt on the edge of the solar system and it is thought that this is where the majority of comets, such as Halley's Comet come from.