SIGNAL FROM PROXIMA CENTAURI

Could a recently detected signal from a nearby star system be from extraterrestrials?

- Nigel Watson

Unusual signals from outer space are exciting as they indicate something new and unexpected, and might even turn out to be much-anticipated communication from an extraterrestrial civilisation. There was even more speculation surrounding the recent detection of signals from the direction of Proxima Centauri because it is our closest stellar neighbour. They were spotted by student Shane Smith, working under the Breakthrough Listen program, as he went through the slow and laborious process of searching through data that was originally collected to detect stellar-flare activity.

The data was collected by the Parkes radio telescope in New South Wales, Australia, during a 26-hour observation period starting on 29 April 2019. Smith sifted through the data for several months in 2020 to see if it showed any sign of a ‘technosignature’ that would indicate Search for Extraterrestrial Intelligence (SETI) activity, and it wasn’t until October 2020 that he finally found something very unusual. It was a narrowband emission at 982.002 megahertz.

The signals had passed the many automated filter systems that sort through millions of signals to rule out terrestrial interference, errors and static. A technique called ‘nodding’ was also used to highlight spurious signals. This involves pointing the telescope at one target in the sky for a fixed period, then moving to a second target for the same amount of time. This is to determine if any unusual signals are coming from a specific place rather than being caused by something more general and mundane. In this case it seems the signal did come from the specific direction of Proxima Centauri and not by anything in the area of the telescope like a nearby microwave oven or anything else terrestrial.