A chunk of material smaller than an asteroid that orbits the Sun is called a meteoroid.

Here's a breakdown of the celestial body classifications:

* Asteroid: A rocky or metallic body that orbits the Sun, typically found in the asteroid belt between Mars and Jupiter. Asteroids are larger than meteoroids.

* Meteoroid: A small rocky or metallic body in space, smaller than an asteroid.

* Meteor: The streak of light we see when a meteoroid enters the Earth's atmosphere and burns up.

* Meteorite: A meteoroid that survives its passage through the atmosphere and lands on Earth.

So, if a meteoroid is smaller than an asteroid, it's still a piece of space debris, but it's just a bit tinier!