Comet
Similar to asteroids, comets are large pieces of rock, metal and ice - except they have tails!
Comets are similar to asteroids with one key difference - they have tails. They are made up of rock and metal, like asteroids, but with much more frozen gases. When comets travel close to the Sun, the heat from the Sun melts these frozen gases and small particles of cosmic dust leaving a tail behind them.
Comets are the frozen remains of the gas and dust that the Solar System formed from. They are formed far away from the Sun and planets, in a bubble surrounding the Solar System called the Oort Cloud. Some comets are periodic, and they visit the Sun regularly. Others only head in towards the Sun once before returning to the outer Solar System forever.
The particles of dust left behind by comets' tails float in space for a long time after the comet has gone. If the Earth's orbit crosses the path of a past comet, the dust burns up in the Earth's atmosphere. These events are called Meteor showers.
