Some 5 billion years from now, the Sun will be running low on supplies of hydrogen for fusion. So it will begin burning helium, a process that will force it to expand into a red giant.

That’s not good news for us. The Sun’s expanding waistline will first engulf Mercury, then Venus and finally, in all probability, Earth. 

In the meantime, our pale blue dot will long have ceased to be a suitable home for us. Of course, humanity will have had plenty of time to come up with an exit strategy, presumably by moving to a more temperate home in a new star system. But this process will not be easy. So how best to go about it?  

Now we have an answer thanks to the work of Bradley Hansen and Ben Zuckerman at the University of California, Los Angeles. These guys say that we can make the task significantly easier by waiting for another star to pass close by and then making the hop. “This lowers the travel time for interstellar migration by ∼ two orders of magnitude,” they say. And their idea has other interesting implications too.

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