A mysterious radio signal from our nearest stellar neighbour, Proxima Centauri, is being ‘carefully investigated’ by a team of alien-hunting astronomers.
Researchers from the Breakthrough Listen Project – a £70m initiative to find alien life through radio telescopes – have been studying the radio waves since April 2019.
Proxima Centauri is 4.2 light years from Earth and has two confirmed planets, a Jupiter-like gas giant and a rocky world called Proxima b in the habitable zone.
The signal was spotted by the Parkes radio telescope in Australia in April or May 2020, according to a report in The Guardian, and, unlike previous radio bursts hasn’t been attributed to any Earth-based or near-Earth human-created source.
It is likely that this signal has a natural explanation, but that hasn’t stopped alien-hunting astronomers from listening more closely than they normally would.
The team say this is one of the most exciting radio signals since the ‘WOW!’ signal in 1977 that led many to speculate it originated from a distant alien civilisation.
Pictured, a not-to-scale representation of how far away Proxima B is from Earth compared to Voyager 1, the farthest man-made object which was launched in 1977
Artist’s rendering of Proxima Centauri system. Portrayed on the right, Proxima c orbits in about 5.2 years around its host star. The system also comprises the smaller Proxima b, on the left, discovered in 2016 that orbits in the ‘habitable zone’ closer than Mercury is to the Sun
Proxima b is an Earth-like rocky world that orbits within the ‘habitable zone’ of Proxima Centauri – that is an area where liquid water could flow on the surface of the planet.
However, as Proxima Centauri is a red dwarf, the habitable zone is very close to the star, meaning the planet is likely tidally locked and exposed to intense radiation, making it unlikely any civilisation has been able to form – at least on the surface.
The radio signal was detected in the 980MHz range, and shifts in the frequency detected by the Parkes telescope are consistent with the movement of a planet.
This suggests it could be evidence of a third planet within the system, rather than signs of an alien civilisation, something researchers say would be ‘very unlikely.’
Pete Worden, director of Breakthrough Initiatives, said the signals are likely interference from Earth-based sources we can’t yet explain.
However, he told The Guardian that it was important to wait and see what the project scientists conclude from their close examination of the signal.
The beam being investigated hasn’t been spotted since the first observation in April or May 2019, causing astronomers to speculate it is similar to the ‘Wow! signal.
This was a short-lived radio signal detected from a distant star system by the Big Ear Radio Observatory in the US in 1977, and labelled with the word ‘WOW!’.
Until now, that has been the best possible candidate astronomers have had to work with for signs of extraterrestrial intelligence – although like this new signal, very little is known about it or what unleashed the signal in the first place.
In this image from the Hubble Space Telescope is our relative neighbour Proxima Centauri, a low mass star in the triple-star Alpha Centauri system. Proxima Centauri is not visible to the naked eye due to its small size – eight times smaller than the Sun
The team from Breakthrough Listen are currently preparing a research paper on the findings, although no date for publication has been set.
Proxima b: The nearest exoplanet to the Earth
Proxima b is the nearest exoplanet to the Earth and the closest planet to the star Proxima Centauri.
It orbits within the habitable zone of the star – but as Proxima Centauri is a red dwarf and much smaller than the Sun this zone is very close to the star.
Proxima b orbits its star every 11.2 Earth days and has a mass of about 1.2 times that of the Earth.
The rocky world is subject to solar winds 2,000 times those experienced on Earth from the Sun.
While it is within a zone where liquid water could form – these stellar winds make it unlikely life could evolve.
The planet was discovered in August 2016 and is likely tidally locked.
For these reasons, despite being in the habitable zone, its actual habitability has not been established.
Studies have suggested the planet could have surface oceans and a thin atmosphere, but that hasn’t been confirmed.
Astronomers won’t know if it has water or an atmosphere until it can be seen transiting in front of its star – which has yet to happen.
If water and an atmosphere are present, even with the extensive radiation, it could be possible life has developed on the planet.
Scientists hope the James Webb Space Telescope – due to come online next year – could detect the atmosphere of Proxima Centauri b.
There is also a theoretical mission to send a probe to the planet in 2069 to search for biosignatures.
The initiative was launched by Silicon Valley tech investor Yuri Milner in 2015 to look for stray or intentional alien signals and designed to last a decade.
Breakthrough Listen involves listening out for ‘technosignatures’ within the range of signals coming from the universe and signatures from human-made objects.
Speaking to the Guardian, Lewis Dartnell, an astrobiologist from the University of Westminster, said it was incredibly unlikely this signal is from an alien civilisation.
‘We’ve been looking for alien life for so long now and the idea that it could turn out to be on our front doorstep, in the very next star system, is piling improbabilities upon improbabilities,’ he told The Guardian.
The professor of science communication said if there is intelligent life as close as Proxima Centauri then it is likely the galaxy is teeming with life.
‘The chances of the only two civilisations in the entire galaxy happening to be neighbours, among 400bn stars, absolutely stretches the bounds of rationality,’ he said.
Proxima b is also likely to be constantly bathed in stellar radiation, making it unlikely liquid water and life ‘as we know it’ could have formed on the rocky world.
An earlier study by University of Sydney researchers found that Proxima Centauri has regular coronal mass ejections that hit the nearby rocky planet.
This discovery was based on a different radio signal that is thought to have been caused by a particularly large ejection or solar flare from the star.
These solar flares would kill all life on a planet too close – and Proxima b is within this danger zone, and so likely showered with sterilising particles on a regular basis.
The planet is also likely tidally locked – just like the Moon is with the Earth – due to its close proximity to the star, meaning one side is always day, the other night.
‘It’s hard to imagine how you can have a stable climatic system and all the things you need to get from bacteria, which are hardy, up to intelligent animal life forms, which certainly are not,’ Dartnell told the Guardian.
‘But I’d love to be proved wrong,’ he added.
It is possible there are other planets, slightly further from the star, that have yet to be discovered by astronomers, but they are likely too far away for liquid water to form.
KEY DISCOVERIES IN HUMANITY’S SEARCH FOR ALIEN LIFE
Discovery of pulsars
British astronomer Dame Jocelyn Bell Burnell was the first person to discover a pulsar in 1967 when she spotted a radio pulsar.
Since then other types of pulsars that emit x-rays and gamma rays have also been spotted.
Pulsars are essentially rotating, highly magnatised neutron stars but when they were first discovered it was believed they could come from aliens.
‘Wow!’ radio signal
In 1977, an astronomer looking for alien life in the nigh sky above Ohio spotted a powerful radio signal so strong that he excitedly wrote ‘Wow!’ next to his data.
In 1977, an astronomer looking for alien life in the nigh sky above Ohio spotted a powerful radio signal so strong that he excitedly wrote ‘Wow!’ next to his data
The 72-second blast, spotted by Dr Jerry Ehman through a radio telescope, came from Sagittarius but matched no known celestial object.
Conspiracy theorists have since claimed that the ‘Wow! signal’, which was 30 times stronger than background radiation, was a message from intelligent extraterrestrials.
Fossilised martian microbes
In 1996 Nasa and the White House made the explosive announcement that the rock contained traces of Martian bugs.
The meteorite, catalogued as Allen Hills (ALH) 84001, crashed onto the frozen wastes of Antarctica 13,000 years ago and was recovered in 1984.
Photographs were released showing elongated segmented objects that appeared strikingly lifelike.
Photographs were released showing elongated segmented objects that appeared strikingly lifelike (pictured)
However, the excitement did not last long. Other scientists questioned whether the meteorite samples were contaminated.
They also argued that heat generated when the rock was blasted into space may have created mineral structures that could be mistaken for microfossils.
Behaviour of Tabby’s Star in 2005
The star, otherwise known as KIC 8462852, is located 1,400 light years away and has baffled astonomers since being discovered in 2015.
It dims at a much faster rate than other stars, which some experts have suggested is a sign of aliens harnessing the energy of a star.
The star, otherwise known as KIC 8462852, is located 1,400 light years away and has baffled astonomers since being discovered in 2015 (artist’s impression)
Recent studies have ‘eliminated the possibility of an alien megastructure’, and instead, suggests that a ring of dust could be causing the strange signals.
Exoplanets in the Goldilocks zone in 2015
In February this year astronomers announced they had spotted a star system with planets that could support life just 39 light years away.
Seven Earth-like planets were discovered orbiting nearby dwarf star ‘Trappist-1’, and all of them could have water at their surface, one of the key components of life.
Three of the planets have such good conditions, that scientists say life may have already evolved on them.
Researchers claim that they will know whether or not there is life on any of the planets within a decade, and said ‘this is just the beginning.’