A global network of astronomers keeps its eyes on the skies to warn the public about potential asteroids that could strike the planet. If one is spotted, they will jump into action to warn us.
If an asteroid was headed toward Earth, here's how NASA would let people know pennlive.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from pennlive.com Daily Mail and Mail on Sunday newspapers.