In 1977, scientists discovered a mysterious signal beaming from space that was so powerful it prompted astronomer Jerry Ehman to write ‘Wow!’ on the telescope’s readout.
For decades, scientists have debated whether this so-called ‘Wow! signal’ could have been an attempt at communication from a distant alien civilisation.
Now, a team of experts has re-examined the signal’s data with modern techniques and found that it could be even stranger than previously thought.
According to the new analysis, the Wow! signal was more than four times stronger than earlier estimates suggested.
The scientists were also able to definitively dismiss a number of natural or human explanations.
There were no known TV stations at that time which could have created the signal, nor were there any satellites passing overhead.
And although scientists believe that the Wow! signal is likely to have a natural cause, they say alien sources can’t yet be ruled out.
Co–author Dr Hector Socas-Navarro, director of the European Solar Telescope Foundation, told Daily Mail: ‘While aliens aren’t completely off the table, it seems that the signal may have originated by a natural astrophysical source. Our goal now is to find that source.’
For decades, scientists have struggled to find any natural process capable of producing the 72–second burst which prompted astronomer Jerry Ehman to write ‘WOW!’ on the telescope’s readout
Using new data, the scientists also refined the area of the sky from which the signal emerged. This map shows the new refined regions (yellow) compared to the previous estimates (grey)
The Wow! signal was detected by astronomers at the Big Ear Observatory in Delaware, Ohio, back in 1977.
Scientists at the observatory were scanning the sky for radio waves as part of a hunt for extra-terrestrials when the telescope picked up an extraordinary signal.
The sudden burst of radio waves was not only exceptionally powerful, but it was also abnormally long-lasting – continuing for a full 72 seconds.
Additionally, scientists noted that the signal’s frequency was in the so-called hydrogen line, which is a band of frequencies emitted by atomic hydrogen.
Since hydrogen is so abundant in the universe, some suggested that advanced civilisations might be using its frequency as a calling card for signalling to other intelligent species.
Strangely, the signal never repeated, and scientists haven’t yet found another burst in the same frequency that is nearly as intense.
However, further study of the Wow! signal has been made difficult by the fact that all the data from the Big Ear Observatory is on paper printouts.
In this new paper, a team of researchers and volunteers painstakingly digitised over 75,000 pages of data from the observatory.
Researchers and volunteers analysed over 750,000 pages of data from the Big Ear Radio Observatory in Ohio, where the Wow! Signal was spotted
For the first time ever, this allowed for the computational analysis of data about the Wow! signal.
Dr Hector Socas-Navarro says: ‘The paper basically rewrites the basic stats of the Wow! signal.’
In addition to showing that the signal had been stronger than previously thought, the researchers have been able to characterise the burst much more accurately.
They narrowed the part of the sky that the signal came from to two small regions, each of which produced a different component of the signal.
The researchers were also able to determine this location with two-thirds greater statistical certainty.
Additionally, this new data slightly revises the signal’s frequency – putting it at 1420.726 MHz rather than 1420.4556 MHz.
That keeps the signal solidly within the hydrogen line, but that small change suggests that whatever produced the signal must have been spinning a lot faster than previously thought.
This means the source must be moving at about 46 miles per second (74 km/s), over double the previous estimate of 18 miles per second (30 km/s/).
The researchers say that the most likely cause of the Wow! signal is an intense beam of energy from a dying star hitting a cloud of cold hydrogen, causing it to produce a laser-like burst which hit Earth
‘This means that when we look for candidates, the ones moving at that speed will stand out, like a very tall person in a large crowd, and it will be easier to identify the emitting source,’ says Dr Socas-Navarro.
Importantly, this research also rules out some natural phenomena that had been suggested as possible explanations.
It had been proposed that a man-made signal could have bounced off the moon and been mistakenly picked up by the observatory.
However, this new analysis clearly shows that the moon would have been on the wrong side of the planet at this time, so nothing could have bounced off it.
Likewise, the sun was not active enough during the year 1977 to produce anything close to the Wow! signal’s intensity.
That means the Wow! signal really must have come from somewhere outside our solar system.
However, there are still many questions remaining about the origins of this mysterious radio beam.
Lead author Professor Abel Mendez, of the University of Puerto Rico at Arecibo, told Daily Mail: ‘We can’t rule out an extraterrestrial communication signal explanation for the Wow! Signal yet, but the evidence points to a natural origin.’
The dying star could have been a magnetar, which produce the most powerful magnetic fields in the Universe and are rare, explaining why the Wow! Signal has not been repeated
Professor Méndez suggests the burst was created when the energy from a dying star called a magnetar hit a cloud of cold hydrogen gas floating through the universe.
If this happened, it would energise the cloud of gas and produce a burst like a giant microwave laser.
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Scientists discover origin of mysterious signal from deep space sent to Earth
Previous research has spotted several signals which appeared to be extremely similar to the Wow! signal, albeit considerably fainter.
Four of those originated from the tiny red dwarf star, Teegarden’s Star, which is just 12.5 light-years from Earth, and is surrounded by clouds of pure hydrogen.
Professor Méndez says: ‘The most likely origin of the Wow! Signal is a maser flare or superradiance emission from a neutral hydrogen cloud.
‘Small clouds emit consistent narrowband signals similar to the Wow! Signal but much weaker, so a cloud became temporarily much brighter due to any of these processes.’
WHAT IS THE FERMI PARADOX?
The Fermi Paradox questions why, given the estimated 200-400 billion stars and at least 100 billion planets in our galaxy, there have been no signs of alien life.
The contradiction is named after its creator, Italian physicist Enrico Fermi.
He first posed the question back in 1950.
Fermi believed it was too extraordinary that a single extra-terrestrial signal or engineering project has yet to be detected in the universe — despite its immense vastness.
Fermi concluded there must a barrier that limits the rise of intelligent, self-aware, technologically advanced space-colonising civilisations.
This barrier is sometimes referred to as the ‘Great Filter’.
Italian physicist Enrico Fermi devised the so-called Fermi Paradox in the 1950s, which explores why there is no sign of alien life, despite the 100 billion planets in our galaxy
If the main obstacle preventing the colonisation of other planets is not in our past, then the barrier that will stop humanity’s prospects of reaching other worlds must lie in our future, scientists have theorised.
Professor Brian Cox believes the advances in science and engineering required by a civilisation to start conquering the stars will ultimately lead to its destruction.
He said: ‘One solution to the Fermi Paradox is that it is not possible to run a world that has the power to destroy itself.
‘It may be that the growth of science and engineering inevitably outstrips the development of political expertise, leading to disaster.’
Other possible explanations for the Fermi Paradox include that intelligent alien species are out there, but lack the necessary technology to communicate with Earth.
Some believe that the distances between intelligent civilisations are too great to allow any kind of two-way communication.
If two worlds are separated by several thousand light years, it’s possible that one or both civilisations would become extinct before a dialogue can be established.
The so-called Zoo hypothesis claims intelligent alien life is out there, but deliberately avoids any contact with life on Earth to allow its natural evolution.