What is dark matter, and what are the problems with it?

Dark matter is any stuff in the universe which we can tell exists but can't see. This means the material is not giving off light which we can see.

Astronomer Fritz Zwicky discovered that the number of things he could see in a galaxy was less than should have been there. So, we must not be able to see some of it. A lot of the objects in the universe we can't see. They are dark matter.

People are still looking for dark matter. 'Brown dwarfs', 'black dwarfs', and planets which we can't see are all dark matter. Other dark matter might be black holes.

Submitted by Ron (age 28, Israel)
(March 13, 1998)

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