Science for the Public mini-series They Didn't Believe It!
Brief stories about science discoveries that were very slow to be accepted
December 02, 2019: Dark Matter

This is the story of an especially important discovery in astrophysics: Dark Matter. Our "normal" matter—everything from all forms of living and inanimate matter here on Earth and elsewhere in the universe -that matter, made of atoms, is only a small percentage of the actual matter in the universe. Most matter is invisible and scientists don't know what it is.