It sounds like a Hollywood blockbuster: a deadly asteroid is on a collision course with Earth. But in reality, it's only a matter of time before a giant space rock threatens to wipe out civilization. An asteroid took out the dinosaurs sixty-five million years ago. Are we next? This episode analyzes the threat and explores the many ways--from a nuclear bomb to ingenious new technology--that experts are proposing to stop Armageddon

Orbits are the dynamics that drive the universe. From the smallest asteroid to the largest super-cluster, everything in the universe is in orbit. We owe our very existence to the stability of earth's orbit — it gave us life and keeps us safe. But we are the freaks. Everywhere else we look we find orbits are chaotic, unstable, and violent. Beyond our solar system we find planets that are blow-torched, stars that eat each other, and black holes that destroy everything in their path. Yet on the very largest scale, orbits are also a creative force. clashing galaxies give birth to new stars and new worlds. on the galactic scale orbits even construct the fabric of the universe itself.

What are the latest discoveries in the deadly world of asteroids? Will a recently returned Japanese spacecraft become the first to bring an asteroid sample back to our planet? What would happen to America's East Coast if the massive asteroid impact that helped form Chesapeake Bay 35 million years ago struck today? And why did President Barack Obama choose an asteroid as the destination for the next great manned mission into space? Learning about these huge space rocks isn't just about science, it's about survival.