What is the atmosphere like on the Asteroids?

The only asteroid likely to have a significant atmosphere is Ceres. Even that's going to be thin though. We'll know more once Dawn approaches it around November 2015. read more

Asteroids have low mass and they are not good at keeping an atmosphere above their surface. Comets have a kind of atmosphere in side. They are loaded with volatiles that turn to gas when heated. read more

Asteroids don't generally have an atmosphere. They are too small to have much of a gravity field and so don't keep gases around them. There is very little free hydrogen in Earth's atmosphere for a similar reason: Hydrogen is the lightest element and escapes Earth's gravity. read more