Astronomers suggest that artificial illumination creates a signature that could point to the existence of civilizations on other worlds — and they say we should get started on a survey of the edges of our own solar system, just in case.

The suggestion comes from Harvard's Abraham Loeb and Princeton's Edwin Turner, in a research paper submitted to the journal Astrobiology. A version of the paper appears on the arXiv.org preprint server and sparked a write-up today on Technology Review's Physics arXiv Blog.

Loeb, who chairs Harvard's astronomy department and is affiliated with the Harvard-Smithsonian Center for Astrophysics, acknowledged that detecting aliens by looking for the glow of their cities would be a long shot. But he pointed out that the cost of the exercise would be low.

"We say that we can piggyback on existing surveys that people are doing anyway. There's no need to use extra resources. ... My philosophy is simple: If we can do it, why not do it and check? Why put blinders on ourselves?" Loeb told me today.

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