Summary:
- Comets are small, icy objects that have very elliptical orbits around the Sun.
- Comet tails form as the comet flies close to the Sun and the outer layers of ice melt and form a glowing coma.
- Particles streaming from the Sun push this gas and dust into a long tail.
- Comets appear for only a short time when they are near the Sun.
- They seem to disappear as they move back to the outer solar system.