Comets are made of left over material from when the Solar System was formed. They are lumps of rock and ice that orbit the Sun from afar and look rather insignificant. That is until they get close to the Sun. When this happens, the heat from the Sun causes the comet to shed material giving it a bright tail that we on Earth can see.
Comets are made up of 3 parts: the nucleus, the coma, and the tail.
The nucleus is the main rock that makes up the body of the comet. It consists of rock, dust and ice water. It can vary in size from 100 meters to 40 kilometres. Some comets have been found to have some organic compounds in them such as amino acids and long chain hydrocarbons.
Sometimes an atmosphere of dust and other material can form around the nucleus. This is called the coma. It is caused by solar radiation.
The life of a comet can end in 4 main ways. If it has enough speed, it can leave the Solar System completely. Others break up and disintegrate due to gravitational forces. Due to material being constantly released, eventually the comet exhausts all of its materials. Sometimes, a comet can crash into a planet like in July 1994 when Comet Shoemakerâ€“Levy 9 broke up into pieces and collided with Jupiter.