Re: How do you know the difference between a comet and a meoter

Hello, Liana.
This is a good question. It is really quite easy to tell the difference between a comet and a meteor.

A comet is usually a very large object, from a few hundred yards to several miles in diameter. Comets orbit the sun like the earth does. Our orbit is almost a circle, but a comet's orbit is very elliptical. If you traced a football on a sheet of paper, that shape would be elliptical. A comet's orbit will bring it in close to the sun where we might be able to see it like Hale-Bopp did and then it will swing way out to the farthest part of our solar system. Comets return time and time again. Sometimes it takes a very long time, thousands of years and sometimes it takes only a few years. Comet Halley will return to near earth each 76 years. When we see a comet in the sky, it will appear not to move very much while we watch even though it is moving at several thousand miles per hour. That is because it is far away and is usually moving towards us or away from us. A comet is like a dirty snowball. It is made of water ice, carbon dioxide ice, dust, rocks and other molecules. As it approaches the sun, the sunlight warms the ices and it sublimates, (that is, a solid turns to a gas without turning to a liquid). This gas points away from the sun and we see it as the comet's tail. The comet and its tail will be visible for several nights, sometimes even weeks. Its position will change a little each night.

Meteors are very different from comets but are sometimes related. A meteor is a small rock. Most are smaller than a grain of sand. They orbit the sun also, but we only see them when they enter our atmosphere. When this happens the meteor gets hot and makes the air around it glow. They move very fast and last only a few seconds. They are what we call "shooting stars" even though they are not stars at all. Just grains of sand. Sometimes bigger ones can actually reach the earth and we call these rocks from space meteorites. There are several meteor showers each year that occur when the earth passes through the dust cloud left by a comet.

I found a neat Web site that explains the differences and has movies, Gary W. Kronk's Comets and Meteor Showers Education Corner. They might take a while to download , though.

I hope that this answers your question. You can stay interested in astronomy by getting involved with a local astronomy club. It is easy to do and a lot of fun. You don't need any equipment, most amateur astronomers are happy to let you look through theirs.