Comets are very white objects that orbit the sun along with the planets. They usually have a very long tail. Comets have very irregular orbits. Their orbits are never even close to that of any other planet. Sometimes they are so irregular that they go all the way beyond the orbit of Pluto before coming back to the sun. These comets are known as long period comets. These comets appear once before disappearing for hundreds of years. Other comets have orbits that are less eccentric. They usually donít go past the orbit of Pluto and take less than 200 years to complete one orbit. Such comets are known as: short period comets.