The Carnival of Space 520 is at the Urban Astronomer

>Universe Today – Advanced Civilizations Could Build a Galactic Internet with Planetary Transits

In a recently-published paper (arxiv – Exoplanet Transits as the Foundation of an Interstellar Communications Network) , Dr. Duncan H. Forgan of St. Andrews University proposed that extra-terrestrial civilizations could be communicating with each other by creating artificial transits of their respective stars. This sort of "galactic internet" could be how advanced species are attempting to signal us right now.

An ETI 'A' can communicate with ETI 'B' if B is observing transiting planets in A's star system, either by building structures to produce artificial transits observable by B, or by emitting signals at B during transit, at significantly lower energy consumption than typical electromagnetic transmission schemes.