Advanced technological civilizations looking for efficient communication from one end of a galaxy to another would best be served by tapping into a network of transiting extrasolar earths. That is, extrasolar earths capable of being observed transiting across the face of their parent stars. Or so says an exoplanet researcher in the U.K.

Kepler-type space observatories out looking for transits of extrasolar earths, could also look for the telltale signatures of optical lasers or even alien macro-engineering projects that might be manipulated to signal another civilization.