Scientists Begin Searching Extraterrestrial Cities
A recent paper authored by "Avi Loeb of the Harvard-Smithsonian Center for Astrophysics and Edwin Turner of Princeton University suggests that we should be scouring faraway planets for urban metropolises."
They suggest that we would already be able to detect a city the size of Tokyo on the dark side of Pluto and developments in imaging technology could improve this range to include some of the the 1,235 Earth-sized planets NASA's Kepler mission has so far identified.
The development is part of a broader realigning of the search for extraterrestrial life. Other scientists have suggested that we should use our own experience as a guide, and look for planets with rapidly changing atmospheric makeup, otherwise known as global warming, which can be a correlate of industrialized or developed life.