Astronomy Practice Exam

Which of the following best describes a comet?

1. Rocky bodies that collide with planets

2. Frozen chunks of rock and metallic particles

3. Clouds of gas and dust around stars

4. Dust particles in the atmosphere

The correct answer is: Frozen chunks of rock and metallic particles

A comet is best described as a combination of frozen gases, dust, and rocky material. This mixture forms the nucleus of the comet, and as it approaches the Sun, the heat causes the frozen gases to vaporize, which creates a glowing coma and often a tail that extends away from the Sun due to solar wind. This unique composition distinguishes comets from other celestial bodies like asteroids, which are primarily rocky. The icy nature of comets allows them to develop spectacular tails when heated, something that is not characteristic of rocky bodies or dust in the atmosphere. This makes the characterization of comets as "frozen chunks of rock and metallic particles" quite accurate, as it highlights both their icy components and their mixture of materials.