Asteroid - Nova Science Now

The Apophis asteroid appears in telescopes as nothing more than a moving speck of light. But the latest data tell us that this rock is bigger than the Rose Bowl and is hurtling towards Earth on what could be a collision course. Most unsettling, if it struck it would release the energy of 100 nuclear bombs. NOVA scienceNOW host Neil Tyson investigates this disturbing threat in our solar system.