To Find Alien Cities, Look for City Lights on Distant Planets

The search for extraterrestrial life elsewhere in our universe has taken many forms, from the radio signal searching undertaken by SETI to the rovers and probes deployed elsewhere in our universe. But if it’s intelligent civilizations we’re looking for, say a couple of Harvard and Princeton researchers, we can likely find them just by literally looking for them. Alien civilizations that evolved in the light from their own stars would likely artificially illuminate their cities, and we should be able to find them by looking for illumination on the night side of exoplanets.
In a paper available on arXiv, Abraham Loeb of Harvard and Edwin Turner of Princeton point out that it’s entirely plausible that other alien civilizations, if they exist, would artificially illuminate their spaces just as we have. And if they have, this light will be distinguishable from natural illumination, even at astronomical distances.