Question: Why can't we see dark matter?

Monique Henson answered on 9 Nov 2015:

Dark matter is thought to be a type of matter that doesn’t interact with light – that means it doesn’t reflect, absorb or emit light. Normally we only see astronomical objects (like stars and galaxies) by looking at the light that it emits. Since dark matter doesn’t emit any light, we can’t see it.

However, we can see the effect of dark matter on other things. Dark matter affects things around it through gravity – for example without dark matter the outer edge of galaxies wouldn’t move as fast as they do. So we can figure out where dark matter is by looking at it’s effect on other things.