Astronomy Practice Exam

What is a meteoroid?

1. Small terrestrial body entering Earth's atmosphere

2. Small extraterrestrial body, remnants of comets or asteroids

3. An asteroid that has changed its orbit

4. Large celestial body that can support life

The correct answer is: Small extraterrestrial body, remnants of comets or asteroids

A meteoroid is defined as a small extraterrestrial body that originates from the remnants of comets or asteroids. These objects are typically smaller than asteroids, ranging from tiny grains to objects that are about a meter in size. They can be composed of rock, metal, or other materials, and are sometimes broken off from larger celestial bodies by collisions or other events in space. This definition highlights the distinction of meteoroids as originating from outer space rather than being terrestrial or related to Earth. For example, option A describes a small terrestrial body entering the Earth's atmosphere, which refers to a meteor once it becomes illuminated and visible as it falls through the atmosphere. Option C, which refers to an asteroid changing its orbit, does not accurately convey what a meteoroid is; rather, it describes an asteroid's potential movement in space. Finally, option D describes a large celestial body capable of supporting life, which is not applicable to meteoroids, as they are much smaller and do not support life themselves. Thus, identifying a meteoroid specifically as a small extraterrestrial body originating from the remnants of comets or asteroids is crucial for understanding its nature and origin.