Out There

Slate:

That’s 1 out of 16. Out of 75 billion stars. That’s a lot of Earths. In fact, using that number and applying some statistics, Dressing and her team calculate that on average, in this part of the galaxy, Earth-like planets are only 13 light-years apart. That’s a long way to walk, but in galactic terms, that’s incredibly close. Only about three-dozen stars are known that are within 13 light-years of Earth. Could one of them bear a planet like home?