Scientists searching for signs of extraterrestrial life usually have their sights set on the sky, asking if anyone is there ...
And it seems that a possible answer has come.
These are radio emissions at 982 mega Hertz recorded from the Parkes telescope, in Australia, and whose frequency seems to come, consistently, from the direction of Proxima Centauri, a star 4.2 light years from the Sun.
Experts believe it could be a technology firm, also known as a
technosignature,
in English.
For decades, biosignatures have been sought in space -molecules or biochemical elements such as methane and oxygen that suggest that there is life-, but until recently they were not
looking for techno-signatures
, elements or traces that would indicate that there is not only life but also there is technology.
The signal "has specific properties that make it meet several of our filters [of possible extraterrestrial intelligence] and
we still can't explain it
," Andrew Siemion, astronomer and principal investigator for Breakthrough Listen, told Scientific American.
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Breakthrough Listen was established in 2015 with the push of astrophysicist Stephen Hawking and with funding from billionaire Yuri Milner.
It is the most formal private project of the search for extraterrestrial intelligence (known as SETI for the English
search for extraterrestrial intelligence
), and it is dedicated to renting for a time the use of radio telescopes around the world to see if it is possible to detect something.
The
signal has been dubbed BLC-1
, an acronym for
Breakthrough Listen Candidate-1
, the project's first possible technosignature candidate.
The broadcasts were recorded between April and May 2019 during a period of 26 hours of use of the Parkes telescope.
But it was until October 2020 that the people of Breakthrough Listen found among all the information collected the
frequency of 982 MHz, which is practically never used for human transmissions.
BLC-1 was recorded for periods of half an hour each over five days and only when the telescope was directed towards Proxima.
It was only in December 2020 that it became known that this signal existed, as scientists are finishing their articles for publication in official magazines.
A very 'forthcoming' sign
Nature tends to emit different signals at various frequencies, for reasons including the trails of a collapsed star or geomagnetic storms (also called solar storms), like one that hit Earth in 1859.
On other occasions it has also turned out that signals that have been investigated by those looking for extraterrestrial life were caused by earthly issues such as interference by the passage of a satellite.
Signals that confused scientists for decades, signals also recorded by the Parkes telescope, turned out to be caused by a microwave oven.
But so far
there is no evidence that this radio wave emission has an earthly or natural origin.
Proxima Centauri is the outer star of our solar system closest to it.
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Proxima is surrounded by at least two planets, one gaseous and one terrestrial.
The second is called Proxima b, discovered in 2016, and is 17% larger than Earth.
It is in what scientists call the "habitable zone": when the distance between a planet and its star is such that temperatures
allow water to be
on the surface.
Although it is possible that there are bodies of water in Proxima b does not mean that there are, especially since NASA discovered in 2017 that the star that serves as its sun emits very intense radiation that could destroy, or has already destroyed, the atmosphere planetary.
In addition, Proxima b's orbit is very short, 11 days, such that one side of the planet is always light and the other is in perpetual darkness, which makes it difficult to have a stable enough climate.
An artist's illustration of what the surface of Proxima b might look like via Reuters / M. Kornmesser for the European Space Agency
"We've been looking for alien life for so long now, and the idea that it might be almost on our doorstep, in the nearest solar system, is a summation of
improbability added to improbability,
" said Lewis Dartnell, an astrobiologist at the University of Westminster, to The Guardian.
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Siemion himself, from Breakthrough Listen, recognized that the signal could well have an anthropogenic origin (created by humans).
"All SETI experiments are done in the middle of a tidal wave of interference, with thousands of signals," Siemion told National Geographic.
"The point is to be able to differentiate between our technology and a distant techno-firm," he added.
That is why he stressed that the fact that they have not yet been able to establish the possible origin of BLC-1 arouses so much interest.
Siemion noted: "The reason why SETI excites us so much, and why we have dedicated our careers to that search, is the same reason that people of all stripes are excited: aliens, how cool!"
With information from The Guardian, Scientific American and National Geographic