Comets

Comets are small celestial bodies that orbit the Sun. They are made up of a nucleus, coma, and a tail. Comets are often referred to as "dirty snowballs" or "icy mudballs" because they are composed of ice, dust, and rock particles.

Nucleus

The nucleus is the solid, central part of a comet. It is made up of ice, dust, and rock. The nucleus is typically only a few kilometers in diameter.

Coma

As a comet gets closer to the Sun, the heat causes the ice in the nucleus to vaporize, creating a glowing cloud of gas and dust around the nucleus called the coma. The coma can grow to be larger than the Earth as the comet approaches the Sun.

Tail

The solar wind and radiation pressure from the Sun push the gas and dust in the coma away from the nucleus, creating the comet's tail. The tail can be millions of kilometers long and always points away from the Sun due to the solar wind's force.

Orbit

Comets have highly elliptical orbits, meaning they are in a long, narrow orbit around the Sun. Some comets have orbits that take them far out into the solar system, while others have orbits that bring them closer to the Sun.

Study Guide

1. What are comets made of?
2. What causes the glowing cloud of gas and dust around the nucleus of a comet?
3. How is a comet's tail formed?
4. What is the shape of a comet's orbit?