What is a chunk of rock or metal orbiting in outer space called?

The correct answer is a meteoroid. A meteoroid refers specifically to a small particle from a comet or asteroid that is floating in space. These objects can vary in size from tiny grains to larger chunks that can be several meters across. When a meteoroid enters the Earth's atmosphere and burns up, it is referred to as a meteor. If it survives the passage through the atmosphere and lands on the Earth's surface, it is called a meteorite.

In contrast, an asteroid is a larger body orbiting the Sun, typically found in the asteroid belt between Mars and Jupiter. Meteorites are fragments of meteoroids that have reached the Earth’s surface. A planet is a much larger celestial body that orbits a star, like Earth or Mars, and is distinct from meteoroids in both size and classification. Understanding these definitions helps clarify the characteristics of each term used for objects in space.