Comets

Most comets are very dim and can only be seen with a telescope because they don’t give off their own light.  The light from the sun shines on them so they look like they are glowing.  They even shine at night because the sun will still be shining on them, but not us.  The closer a comet gets to the sun, the brighter it will glow.

What Are Comets?

A comet is a large, icy rock that travels in an orbit around the sun.  An orbit of a comet is very long, like an oval.  You might think that the comet would also smack into the Sun.  You have to remember though that a comet is in an orbit around the Sun. Most comets have a rocky center called a nucleus.  Around it are bits of dust and rocks that are held together by ice and frozen gases.  When the comet gets closer to the sun, the ice and gas start to melt and form the tail.  A comet, from head to tail, could be over millions of miles long!

How the Tail Is Created

When the comet gets closer to the Sun, it begins to hit atomic particles that are released from the Sun (a solar wind).  When the comet gets about 150 million miles from the Sun, about the distance between Mars and the Sun, the solar wind is strong enough to push some of the melted ice back away from the comet.

There are three types of tails.  They are:

Every time a comet goes around the sun, it loses a little more ice, gas, and dust.  Soon, all that is left of the comet is the rocky center.  Comets that don’t have a center will disintegrate over time.

“Comets.” Encarta Encyclopedia, 1996.

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