The Mystery of Black Holes

This week, scientists reported a black hole is hurtling through our galaxy, dragging a star behind it. While they assure us it won?t swallow the earth, it does raise the question: What are these things anyway? And what?s keeping them from gulping up the universe? Laura explores black holes with John Gianforte, Astronomy teacher at the College for Lifelong Learning www.cll.edu and columnist for Fosters Daily Democrat www.fosters.com.