Asteroid

An asteroid is a naturally occurring solid object that is smaller than a planet. Asteroids are often found in asteroid belts orbiting a star, or, in some cases, trailing a planet in a Lagrangian point.

Asteroids can also be used as habitats or military bases, with artificial gravity often provided by rotation. Notable examples of this were the Insurrectionist hideouts Eridanus Secundus and the Rubble, the latter being a remarkable feat of engineering, composed of hundreds of asteroids with independent propulsion systems connected by flexible docking tubes. The Covenant used asteroids such as K7-49 as refineries and shipyards.

In a skirmish following the Callisto Incident in 2494, an asteroid was used by the Insurrectionists to gain a tactical advantage in battle, using a outward-facing nuclear explosive device buried in an asteroid, greatly increasing the destructive power of the weapon in vacuum environment by providing enough reactive mass to destroy one UNSC ship and cripple two.

Known asteroids or asteroid belts

 * Bonanza Asteroid Belt
 * Eridanus asteroid belt
 * Eridanus Secundus
 * Indra Asteroid Cluster
 * Origami Asteroid Field
 * The Rubble
 * K7-49

Trivia
The depictions of asteroid belts in Halo: Reach and Halo: Fall of Reach - Boot Camp follow a common popular culture depiction of an asteroid belt, where the asteroids float in an extremely dense field within visible distance of each other. In real life, asteroids are spaced millions of kilometers apart and it would be highly unlikely to even see one when passing through an asteroid field.