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	Dark Matter
	Dark matter was once called "missing matter". It was called this because scientists looking at the sky could not find it.

Matter is anything that takes up space and has mass. We are used to matter which we will call visible matter. Visible matter can be seen because it gives off light or reflects light given off by another object. Dark matter cannot be seen. It does not give off light or reflect light.

Scientists believe that over ninety-percent of the matter in the universe is dark matter. They also believe that by studying dark matter they will gain new information about the universe. Some of the information they hope to discover is the size, shape and future of the universe. Scientists also hope to learn about how galaxies formed by studying dark matter.

Scientists cannot see dark matter, so they have a special way of studying it. Scientists study dark matter by looking at how it affects visible matter. Scientists use computers and satellites to study dark matter. The Hubble Space Telescope has taken pictures that have helped scientists discover where dark matter can be found.

A Question What is the difference between regular matter and dark matter?