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Pictures of Earth’s nightside shot from space show a lot of islands of light — the glow of cities and towns. When you add up all of that light, though, it isn’t much — the nightside is pretty dark.
But a study this year suggested that if there’s a civilization on a nearby exoplanet, it might produce enough nighttime light to see with a giant new space telescope.
Proxima Centauri b is one of the two planets known to orbit Proxima Centauri, our closest neighbor star. The star is so small and faint that you need a telescope to see it, even though it’s just four-and-a-quarter light-years away.
Proxima Centauri b is at a distance from the star where conditions are fairly comfortable for life. That makes the Earth-sized planet a candidate for studies by James Webb Space Telescope. It could look for compounds that are produced by life in the planet’s atmosphere, for example.
Abraham Loeb and Elisa Tabor suggested another way to hunt for life — in this case, an advanced civilization: Look for the glow of cities on the planet’s nightside.
The night would have to be really lit up — at least five percent as bright as Proxima Centauri. And the light would have to be concentrated in a narrow range of wavelengths.
The odds of such a civilization living there are tiny, so Webb isn’t likely to see any nightlights. But future space telescopes might extend the range to other stars — and look for the glow of alien cities.
Script by Damond Benningfield