The Earth has a long shelf life, but it is, alas, temporary. Before the Sun explodes in 5 billion years, there are a number of extraterrestrial threats to our planet, from rogue black holes to magnetars.
There are at least seven ways the Earth could be pulverized even before our Sun turns into a red giant 5 billion years from now. Hypervelocity stars are one. The literal shooting star, these balls of fire millions of miles across have such a high velocity that they could break their gravitational orbit and go screaming into space, perhaps with a trajectory for Earth. Black holes are not stationary, either, and because not even light can escape their grasp, they are difficult to detect. Scientists estimate that there are hundreds of such rogue black holes roaming the galaxy. Is one headed for our planet?
What’s the Big Idea?
The world will end in the existential crisis of all existential crises. But will it go out with a bang or a whimper? Will humans undo our own home or will the final blow come from outer space? Could gamma rays, a space rock, black hole, cosmic radiation burst, escaped star, magnetar or vacuum metastability get us before we get ourselves? Or at least before the Sun swallows the Earth in flame? Not a pleasant topic to ponder, perhaps, but one we should keep in mind both for psychological perspective and to remind us, as Stephen Hawking does, that our ultimate goal should be to get off this rock.