Eastern Iowa Observatory & Learning Center
1365 Ivanhoe Road
Astronomer Fritz Zwicky first postulated the existence of dark matter in the universe in the 1930’s, and evidence has been piling up ever since. While normal matter is the kind of matter that stars and planets and people are made of, dark matter is different. Dark matter doesn’t give off light like a star, and it doesn’t reflect light like a planet, so astronomers can’t see dark matter. Instead, dark matter attracts normal matter due to gravity, and that’s it. This talk will describe how astronomers use stars and gas and galaxies to detect a substance that they can’t see.