On the hunt for dark matter

Dark matter, one of cosmology’s most curious mysteries, has yet to be seen. But theorists have good reason to believe that it exists, and that galaxies, stars, and planets could never have formed without the gravitational attraction that dark matter exerts. Guest: Neil deGrasse Tyson, director of the Hayden Planetarium and host of NOVA ScienceNOW. He’s been sleuthing with some top-notch dark-matter detectives.