The Good, The Bad, The Ugly
Asteroids , sometimes grouped with centaurs, Neptune trojans and trans-Neptunian objects into minor planets or planetoids, are a class of small Solar System bodies in orbit around the Sun.
The term "asteroid" was historically applied to any astronomical object
orbiting the Sun that was not observed to have the characteristics of
an active comet or a planet, but it has increasingly come to particularly refer to the small rocky and metallic bodies of the inner Solar System and out to the orbit of Jupiter. As small objects in the outer Solar System
have begun to be discovered their observed composition differs from the
objects historically termed asteroids. Harbouring predominantly volatiles-based
material similar to comets rather than the more familiar rocky or
metallic asteroids, they are often distinguished from them.