Ragnarok (The End Of A World)

It's just another day at Lowell Observatory, Arizona until Amy, one of the astrophysicists on duty, notices something on a computer screen that shouldn't be there.  It's an asteroid, a Near-Earth Object, and its orbit trajectory will lead it to collide with Earth. And it's as big as the asteroid that wiped out the dinosaurs.​NASA's Planetary Defense Coordination Office springs into action with thr...