PRESENTATION OUTLINE
A comet is an icy small Solar System body that, when passing close to the Sun, heats up and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail.
Nucleus of a Comet
The first part of a comet is the nucleus. Comet nuclei were formed in the earliest stages of our solar system billions of years ago. They are made of rock, iron (troilite), dust and a variety of frozen chemicals including water and gases like carbon dioxide, nitrogen, carbon monoxide, ammonia and methane. Each comet nucleus, like each planet in our solar system, contains different chemicals in
Coma of a Comet
The cold, solid nucleus warms as it approaches the Sun and the comet begins to transform. Expelled water, dust, gas and debris form a fuzzy haze around the nucleus called the coma. In January 2009, a U.S. satellite named Explorer observed Comet Lulin’s (C/2007 N3) nucleus expelling 800 gallons (3,000 liters) of water per second.
Dust Tail of a Comet
As the nucleus and coma move closer to our Sun, the comet continues its transformation into one of the most breathtaking objects our solar system. Heavier particles and debris are released by vaporizing ices. They form another part of the comet called the dust tail. The dust tail is primarily affected by the comet’s orbital path, which means this tail curves behind the nucleus as it orbits the Sun. There can even be more than one dust tail.
Ion Tail of a Comet
Some ionized gases are pushed directly away from the Sun by the Sun’s high speed solar wind. These ionized gases form the comet’s blue, ion tail. Comet Hale-Bopp (image left) is a good example of a comet with a very distinct ion tail and dust tail.
Both the ion and dust tail(s) can be hundreds of thousands or even millions of miles long.
Comet Trail (Dust Trail)
Every comet leaves behind a dust trail, consisting of dust and chunks of debris that mark the path the comet travels through the inner solar system. Earth returns to the same relative position in space once every 365.242 days. If a comet passed close to this position in space, then our planet passes through the dust and debris left by this comet once every year on the same day or days. This results in a meteor shower.
