Video: "Tracking Killer Comets Before They Strike" (PBS)
04:26 min extract from PBS' "Tracking Killer Comets Before They Strike", broadcasted on October 17, 2014.
"Collectively, near-Earth object surveys have catalogued about 12,000 asteroids and comets, including 1,000 that are six-tenths-of-a-mile in diameter and larger, big enough to cause a global catastrophe." -Miles O’Brien, PBS Science Correspondent