Question: What is the universe made of?

Monique Henson answered on 9 Nov 2015:

Lots of things! Stars, planets, big clouds of gas and dust, asteroids, comets, masers (like lasers but using microwave radiation), black holes, dark matter and so many other things. I don’t think I even know everything that makes up the Universe.

Lots of these things have things in common. For example, stars, planets, gas clouds, asteroids, comets etc all interact with light. However, dark matter doesn’t. So sometimes astronomers split matter into two types: the stuff that interacts with light (normal matter) and the stuff that doesn’t (dark matter). It turns out that dark matter is more than 84% of all the matter in the Universe (even though we can’t see it).

There’s also this other stuff, called dark energy. We don’t know what it is yet, but it’s making our Universe expand faster and faster. It’s different from normal matter and dark matter, as we don’t think it’s matter at all. This accounts for most of the Universe.

This makes astronomy really exiting, as we still don’t know what the majority of our Universe is.