Comets ‘pack more of a punch’ than asteroids and could wipe out humanity, Nasa warns

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We hear a lot about the apocalyptic threat posed by doomsday space rocks. But there’s another type of celestial killer that ‘packs more of a punch’ than asteroids, Nasa has warned. Asteroids tend to be made of metal or rock and follow long orbits which makes it easy for us to track the really big monsters. Comets, on the other hand, could appear out of nowhere and cause the demise of every species living here on Earth.

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