Alien Hunters Detect Mysterious Radio Signal From Closest Star System

Scientists have received a signal from a nearby solar system that is one of the most likely candidates for an extraterrestrial transmission ever recorded — so far. According to a report by The Guardian, the signal came from Proxima Centauri, the closest star to our own and one that is known to have a planet that could theoretically support life. The signal has passed many of the tests used to determine if it is of intelligent design, but many more tests remain.

The signal was reportedly detected in April of 2019 by a project called Breakthrough Listen — a part of the wide-ranging Search for Extraterrestrial Intelligence (SETI). Breakthrough Listen buys observation time on radio telescopes around the world, then examines that data for signs of artificial signals that could indicate intelligent life. Last year, the scientists used the Parkes radio telescope in Australia to examine Proxima Centauri when this distinctive signal caught their attention.

The data gathered by Parkes was saved for later, closer observation, which was conducted by an intern in a SETI program at Berkeley, Shane Smith. Smith — an undergraduate student from Michigan — was reportedly the first to notice the distinct, narrowband signal that has captured the scientific community's attention.

This signal stands out for several reasons — particularly its place on a narrow band of the radio spectrum at 982 megahertz. Berkeley scientist Andrew Siemion, the head of Smith's internship, told Scientific American: "We don't know of any natural way to compress electromagnetic energy into a single bin of frequency." The 982 megahertz band is not typically used by human-made satellites or spacecraft, either.

The standard procedure for SETI programs is to subject the signal to hundreds of tests, all designed to determine whether it could be natural in origin, or if it could have come from interference on earth. This signal passed an unusual number of those tests, and Siemion said: "It has some particular properties that caused it to pass many of our checks, and we cannot yet explain it."

It's also notable and exciting that this historic signal appeared to come from Proxima Centauri, which is known to have two planets, at least one of which seems habitable. The first is called "Proxima b" by scientists — a planet about 1.2 times the size of earth, in an 11-day orbit around its star. Its climate could support liquid water on a rocky surface, though scientists note that Proxima Centauri's intense stellar flares could have damaged the planet's atmosphere. The other planet is called "Proxima c" — a larger, colder planet further from its star.

While scientists are excited about this signal, they stressed in their interviews that it is most likely not a sign of extraterrestrial life. Breakthrough Initiatives' executive director, Pete Worden, said: "The most likely thing is that it's some human cause. And when I say most likely, it's like 99.9 percent."

Other scientists at every level of the SETI projects agreed, pointing out some aspects of the signal that make it seem less likely to be artificial. For example, the signal does not contain modulation, which would theoretically be used to convey information — instead consisting of just a single "tone." For another thing, its "drift" does not appear to match the relative movements of earth and Proxima Centauri.

Most disappointingly, follow-up observations of the star using the Parkes telescope have not picked up the signal again, which scientists say is a requirement for a theoretical intelligent transmission. Nonetheless, this remains one of the most likely candidates for an extraterrestrial transmission ever detected — compared by some to the historic "Wow! signal" discovered in 1977. Scientists say they intend to continue testing this signal and studying Proxima Centauri for more answers.