Types of asteroid

Most asteroids are known to reside in the asteroid belt but, on occasion, they might be drawn into the inner Solar System, for example when Jupiter knocks them out of their orbits. We can study these near-Earth asteroids as they make their way past us, and we’ve also sent numerous spacecraft to various asteroids to study them in greater detail. Here, we’ve taken a look at the three main types of asteroid we know of to date.


Carbonaceous (C-type) asteroids comprise over 75% of all known asteroids. They are dark with a similar composition to that of the Sun, but without most of the hydrogen, helium and other volatiles present in our star. They are mostly found in the outer regions of the asteroid belt.


Silicaceous (S-type) asteroids account for 17% of all the asteroids we know of and are therefore the second most common type. They’re brighter than C-type asteroids and are mostly made of iron and magnesium-silicates. They tend to dominate the inner asteroid belt around Mars.


Metallic or M-type asteroids make up most of the rest of the asteroids we know of. They’re generally slightly dimmer than S-type asteroids and their compositions are dominated by metallic iron. Most of these asteroids hang out in the central region of the asteroid belt.

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