Radio signal is the best possible evidence for extraterrestrial life The Breakthrough Listen team has been scanning skies for technosignatures – indicators of technology developed by advanced alien civilizations. Prior to their discovery, the team’s effort had been fruitless, as many promising detections turned out to be man-made. But one signal, labeled Breakthrough Listen Candidate 1 (BLC1), stood out among the several radio signals the researchers picked up while examining data taken using the Parkes Observatory in Australia during a 2019 search for stellar flares from Proxima Centauri. The star has two known planets in orbit: an inhabitable gas giant and an Earth-like rocky planet, called Proxima b, located in the star system’s habitable zone, an orbital region around a star where liquid water can exist on a planet.