Which term describes a small chunk of rock or iron traveling through space?

The term that accurately describes a small chunk of rock or iron traveling through space is "meteoroid." This classification is specifically used for objects that are significantly smaller than asteroids; typically, meteoroids range in size from tiny grains to objects up to a meter in diameter. When these meteoroids enter the Earth's atmosphere and begin to burn up due to friction with the air, they create a visible streak of light known as a meteor.

In contrast, asteroids are larger bodies primarily found in the asteroid belt between Mars and Jupiter, and comets are distinct for their icy compositions and often spectacular tails when in proximity to the sun. A meteor, therefore, refers to the phenomenon observed when a meteoroid falls into the atmosphere, rather than the object itself. Thus, "meteoroid" is the precise term for those small chunks of material traveling through space.