Types of asteroids

Note: This image and the accompanying text below were updated on 15 June 2026 to more accurately represent the classification of asteroids.

Classifying asteroids is complex, and several different sorting schemes exist. But in general, most asteroids can be classified into one of two groups: C and S. 

More than three quarters (75%) of known asteroids belong to the carbonaceous (carbon-rich) C-group. Very dark and mostly made of carbon, C-group asteroids are thought to be the most ancient, reflecting the very materials that existed when the Solar System formed. They mostly live in the outer regions of the main asteroid belt. 

Next, around a fifth (20%) of known asteroids are siliceous (or stony) S-group, composed of silicate rocks, including metal-bearing minerals. Many S-group asteroids are fairly bright through reflection of sunlight, and they are mostly found in the inner regions of the main asteroid belt.

The rest – around 5% of asteroids – can’t be classified as either carbon-rich or stony. They are highly diverse, some being rocky and some consisting of metals like nickel or iron. Some are very dark and some are very bright. The metallic ones, for example Psyche, may be fragments of larger bodies that once had liquid cores, before they were shattered in collisions long ago.

Discover more about asteroids here.