Right before I went on vacation and we took our winter hiatus, news leaked that the Breakthrough Listen project had found their first candidate signal in their search for extraterrestrial life. The headlines went a little wild, and of course, my other job dealt with a bit of the fallout. Keep in mind that we’re covering this story because it was newsworthy, but the papers aren’t published, yet.

The signal was found in archival data from 2019 and came from radio emissions from basically Proxima Centauri, only 4.2 light-years away. The expectation, because scientists aren’t optimistic on this front, is that we will find a somewhat terrestrial source for the signal. But that source hasn’t been found, yet. Andrew Siemion, Breakthrough Listen’s principal investigator, said: It has some particular properties that caused it to pass many of our checks, and we cannot yet explain it.

The signal was found in data from the Parkes Observatory in Australia while the telescope was studying Proxima Centauri. It’s a narrow-beam signal around 982 MHz, which is narrower than what we usually observe from human-made satellites and spacecraft. There is also an intriguing drift to the signal, and that mimics what we see when planets are in motion and giving off their own signals. However, the signal could be coming from a traveling spacecraft of our own design.

As Seth Shostak of the SETI Institute wrote: With the large volume of space technology orbiting the Earth and beyond, it can be extremely challenging to pinpoint which signals may be non-human-made. 

The signal needs to be re-observed before any conclusions can be made. So it’s still not aliens. But it’s not NOT aliens.

More Information

Smithsonian article

Scientific American article

SETI Institute article