Forget an asteroid hitting the planet and wiping out life on earth, there's a more urgent and imminent danger which has seen Nasa get involved with - Yellowstone Caldera - a super-volcano in the U.S.
Its one of 20 known so-called super-volcanoes around the world which, if it erupted, could produce so much fiery magma that the ensuing ash cloud might starve the Earth of sunlight in a choking, years-long volcanic winter.
It's also thought the Yellowstone volcano erupts once every 600,000 years or so, and it's been about that long since its last super-eruption.
Don't worry though, Brian Wilcox is with NASA's Jet Propulsion Laboratory and has been part of the team coming up with a strategy to counter the threat.
We also have a few super volcanoes in New Zealand by the way!