Comet

A comet is a small celestial body that orbits the Sun and releases gas or dust. Comets are often referred to as "dirty snowballs" or "icy dirtballs" because they are composed of ice, dust, and rocky material.

Structure of a Comet

Comets have three main parts: the nucleus, coma, and tail.

• Nucleus: This is the solid, central part of the comet, composed of ice, gas, and dust.
• Coma: As a comet approaches the Sun, the heat causes the nucleus to release gas and dust, creating a glowing cloud around it called the coma.
• Tail: The solar wind and radiation pressure cause the dust and gas in the coma to form a tail that points away from the Sun.

Composition of Comets

Comets are made up of various ices such as water ice, carbon dioxide ice, and ammonia ice, as well as rocky material and organic compounds.

Orbit and Observation

Comets have highly elliptical orbits that can take them far from the Sun to the outer solar system and then back to the inner solar system. They are often visible from Earth as they approach the Sun and their tails become more prominent.

Study Guide

1. What are the main parts of a comet?
2. Describe the structure of a comet's nucleus.
3. What causes a comet's tail to form?
4. What are comets made of?
5. How do comets move in the solar system?