Here's What We Know About Dark Matter

Today, NASA and European Space Agency scientists announced that they've detected the first hints of dark matter from a detector on the International Space Station. What is dark matter? Dark matter makes up about a quarter of the universe, but we don't really know what it is. We can't visibly detect it because it does not emit or absorb light -- hence its "dark" name -- but based on our knowledge of the universe, something must be out there, creating mass that we can measure but can't see. Becaus...