A Hubble Space Telescope photo of Pluto

Before Ed Turner and Avi Loeb tell you about their research, they want to make one thing perfectly clear: they do not claim there's a city on Pluto. But if there were, they say, we could see it. And, as they suggest in a paper they've submitted to the journal Astrobiology, it's worth taking a look, just in case.

The whole thing began a couple of years ago when Loeb and Turner, astrophysicists at Harvard and Princeton, respectively, were at a conference in Abu Dhabi. The organizers sent them on a tour of nearby Dubai, where the guide bragged that his gleaming, ultramodern city was so brightly lit at night that from space it would outshine London, Paris or New York.

That got the pair thinking: how far away could you see a major city on another world using only existing telescopes?

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