There's probably no intelligent life in the outer solar system. But it couldn't hurt to check.
A new study suggests that astronomers could soon look for city lights on distant worlds. Astronomical campaigns already in the works, for instance, could spot a large illuminated city as far away as the Kuiper Belt, where Pluto and many other icy worlds orbit. The research is on the site arxiv.org. [Abraham Loeb and Edwin L. Turner, "Detection Technique for Artificially-Illuminated Objects in the Outer Solar System and Beyond"]
Artificial illumination on a Kuiper Belt Object would stand out because it would vary less than reflected sunlight does when the world moved toward or away from the sun.
“Just by checking for how their brightness varies with distance, you would be able to identify interesting candidates.”
Princeton's Edwin Turner, a co-author of the new study. Unfortunately, Turner says, no telescopes currently in the works would be powerful enough to identify city lights in other planetary systems. Unless the aliens like things really bright.
“Forthcoming facilities might be able to see artificial lighting on another world if it’s really much brighter than we use. It begins to become plausible that we could detect it. A million times would be for sure, and 10,000 times we might have a chance.”
[The above text is a transcript of this podcast.]