Scientists Decipher Alien Signal From Proxima Centauri

Astronomers from the Breakthrough Listen project have determined that the BLC1 artificial radio candidate discovered two years ago, which was believed to have come from an area near Proxima Centauri, is in fact anthropogenic. This conclusion was made after careful analysis of the signal’s characteristics. 

The mysterious signal from Proxima Centauri was not sent by aliens after all

Breakthrough Listen

The Breakthrough Listen program started in 2015 and searches for possible signals of artificial origin and emanating from other stellar systems using ground-based optical and radio telescopes. One of the targets that scientists are tracking is the closest star to the Sun, Proxima Centauri, a red dwarf, around which two exoplanets revolve. It was observed in the frequency range from 700 megahertz to 4 gigahertz using the Parkes radio telescope.

Signal from an exoplanet near Proxima Centauri

In December last year, there were reports that Breakthrough Listen recorded a narrowband signal at 982 megahertz in April and May 2019, which, presumably, came from an exoplanet near Proxima Centauri. It received the designation BLC1 (Breakthrough Listen Candidate 1). The signal was observed for about five hours, had characteristics similar to those expected from the technosignature, and was not subsequently registered. Nevertheless, almost immediately after the discovery of the signal, scientists had doubts about its alien nature.

Dynamic spectrum of the BLC1 signal. Credit: Shane Smith et al. / Nature Astronomy, 2021
Dynamic spectrum of the BLC1 signal. Credit: Shane Smith et al. / Nature Astronomy, 2021

Latest research

A group of astronomers led by Shane Smith from the University of California at Berkeley published the results of an analysis of the BLC1 parameters, the purpose of which was to confirm or deny the signal’s status as a potential radio engineering signature.


Scientists concluded that, despite the fact that BLC1 was observed only in the direction of Proxima Centauri and cannot be a signal from an aircraft (although it is in the frequency band reserved for aeronautical radio navigation) or a near-earth satellite, it does not meet the criteria of technosignature.

The signal from Proxima Centauri was picked up by the Parkes Murriyang radio telescope in Australia. Credit: CSIRO/A. Cherney
The signal from Proxima Centauri was picked up by the Parkes Murriyang radio telescope in Australia. Credit: CSIRO/A. Cherney

What caused it?

Instead, it is the result of the intermodulation of many human-made interference sources. Nevertheless, according to scientists, observations of Proxima within the framework of the project should be continued, covering other ranges of electromagnetic waves, such as optical, infrared, or X-ray.

No aliens still but maybe soon?

In the end, as always, the signal was not caused/sent towards us by aliens. However, there are hundreds of other similar bursts that are yet to be deciphered, and who knows, perhaps there will be at least one that was not caused by humans. And since the search for alien life is at its peak, we have a separate article on technosignatures, the types of evidence that astronomers will look for on distant worlds. Read all about the future of alien-hunting in our article “Looking for Technosignatures on Distant Alien Worlds is a Must for Astronomers“.

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Choi, C. Q. (2021, October 26). Mysterious Radio signal from Proxima Centauri was definitely not aliens.
Price, D. C. (n.d.). That exciting signal thought to be from Proxima Centauri has now been resolved. ScienceAlert.
Siraj, A., & Loeb, A. (2021, January 11). The Copernican principle rules out BLC1 as a technological radio signal from the Alpha Centauri System.
Smith, S., Price, D. C., Sheikh, S. Z. (2021, October 25). A radio technosignature search towards Proxima Centauri resulting in a signal of interest. Nature News.
Specktor, B. (2021, October 26). Sorry folks: ‘alien’ signal from Proxima Centauri was likely just a broken computer on Earth. LiveScience.
Witze, A. (2021, October 26). A mysterious ‘alien beacon’ was actually a false alarm. Scientific American.

Source: Curiosmos

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