Comets

A comet is a small, icy body that orbits the Sun. It is made up of dust, rock, and frozen gases such as water, carbon dioxide, methane, and ammonia. Comets are often referred to as "dirty snowballs" or "icy dirtballs" because of their composition.

Structure of Comets

Comets have a few main components:

• Nucleus: This is the solid, central part of the comet, made up of ice and rock.
• Coma: As a comet gets closer to the Sun, its ice begins to vaporize and forms a cloud of gas and dust around the nucleus, called the coma.
• Tail: The solar wind and radiation pressure from the Sun push the gas and dust away from the coma, forming a tail that can stretch for millions of kilometers.

Orbit and Origin

Comets have highly elliptical orbits, which means they can spend most of their time in the distant reaches of the solar system before swinging in close to the Sun. Many comets come from the Kuiper Belt and the Oort Cloud, which are regions beyond the orbit of Neptune that contain icy bodies left over from the formation of the solar system.

Study Guide

Here are some key points to remember when studying comets:

1. Describe the composition of a comet.
2. Explain the structure of a comet, including the nucleus, coma, and tail.
3. Discuss the origin of comets and their orbits.
4. Compare and contrast comets with other celestial bodies such as asteroids and meteors.
5. Research famous comets throughout history and their impact on our understanding of the solar system.