Have you ever wondered if we are alone in the universe? If there are other intelligent beings out there, how would they communicate with us? And what would they say?
These are some of the questions that have fascinated scientists and enthusiasts for decades, especially those involved in the search for extraterrestrial intelligence (SETI). SETI is a scientific endeavor that aims to detect and analyze signals from outer space that may indicate the presence of alien civilizations.
One of the most intriguing and controversial signals ever detected by SETI was the Wow! signal, a strong narrowband radio signal that appeared to come from the direction of the constellation Sagittarius on August 15, 1977. The signal was picked up by Ohio State University's Big Ear radio telescope, which was then used to scan the sky for potential extraterrestrial messages.
The signal was so remarkable that it caught the attention of astronomer Jerry R. Ehman, who was reviewing the recorded data a few days later. He was so impressed by the result that he circled the reading of the signal’s intensity, “6EQUJ5”, on the computer printout and wrote the comment “Wow!” beside it, giving the signal its popular name.
What made the Wow! signal so special?
The Wow! signal had several characteristics that made it stand out from the usual background noise and interference that radio telescopes encounter. Some of these features were:
The signal was very strong, reaching a peak intensity of 30 times the average background level.
The signal was narrowband, meaning that it had a very specific frequency of 1420 megahertz (MHz), which is naturally emitted by hydrogen, the most abundant element in the universe. This frequency is also protected by international agreement from human-made transmissions, making it an ideal channel for interstellar communication.
The signal matched the expected profile of an extraterrestrial origin, as it rose and fell in intensity according to the rotation of the Earth and the movement of the telescope.
The signal lasted for 72 seconds, which was the maximum duration that the Big Ear telescope could observe any given point in the sky.
What was the source of the Wow! signal?
Despite its remarkable features, the Wow! signal has never been detected again, despite several attempts by Ehman and others to re-observe the same region of the sky. This has led to many speculations and hypotheses about its origin, ranging from natural phenomena to human-made interference to alien communication.
Some of the possible explanations that have been proposed are:
A comet or an asteroid passing by: Some researchers have suggested that the signal could have been caused by a comet or an asteroid that reflected or emitted radio waves at 1420 MHz. However, this would require a very large and unusual object with a high concentration of hydrogen molecules. Moreover, no known comet or asteroid was in that area of the sky at that time.
A military satellite or a spy plane: Another possibility is that the signal could have been generated by a secret human-made device orbiting or flying over Earth, such as a military satellite or a spy plane. However, this would violate the international agreement that prohibits transmissions at 1420 MHz. Moreover, no such device has been identified or claimed by any country or agency.
A glitch in the equipment or a hoax: A more mundane explanation is that the signal could have been an artifact of the Big Ear telescope itself or a prank by someone who tampered with the data. However, this would imply a very sophisticated and elaborate hoax that would have to fool both Ehman and his colleagues who checked and verified the data. Moreover, no evidence of such a glitch or a hoax has ever been found.
A message from an alien civilization: The most exciting and controversial explanation is that the signal could have been a deliberate transmission from an extraterrestrial intelligence trying to contact us. However, this would raise many questions about who they are, where they are, why they chose that frequency and format, and what they meant by “6EQUJ5”. Moreover, no other similar signals have ever been detected since then.
What does “6EQUJ5” mean?
One of the most intriguing aspects of the Wow! signal is its intensity reading, which was encoded as “6EQUJ5” on the computer printout. This string of characters has often been misinterpreted as a message or a code sent by aliens, but in fact it is simply a representation of how strong the signal was over time, expressed in the particular measuring system adopted for the experiment.
The Big Ear telescope used a base-35 number system to record the signal intensity, which ranged from 0 to 35. The numbers from 0 to 9 were represented by themselves, while the numbers from 10 to 35 were represented by the letters from A to Z. For example, A meant 10, B meant 11, and Z meant.
The intensity was measured every 12 seconds, and each measurement was printed as a single character on the paper. The highest possible intensity was Z (35), but the Big Ear telescope never recorded such a value. The highest intensity ever recorded before the Wow! signal was U (30).
The Wow! signal, however, reached an intensity of U (30) and then exceeded it, reaching an unknown value that was printed as a space on the paper. The next measurement was J (19), followed by 5 (5). The signal then decreased in intensity until it faded away.
The string “6EQUJ5” therefore means that the signal had an intensity of 6 for 12 seconds, then increased to an unknown value for 12 seconds, then decreased to 19 for 12 seconds, then to 5 for 12 seconds, and so on. The total duration of the signal was 72 seconds, which corresponded to six measurements.
The string “6EQUJ5” does not have any inherent meaning or message, other than indicating that the signal was very strong and unusual. However, some people have tried to find hidden meanings or patterns in it, such as anagrams, mathematical formulas, or references to books or movies. None of these interpretations have any scientific basis or evidence.
The Wow! signal remains a mystery that has not been explained by any natural or artificial source. Whether it was a message from an alien civilization or not, we may never know for sure. But it certainly captured our imagination and curiosity about what lies beyond our planet.
What is the current status of the Wow! signal?
The Wow! signal remains an unsolved mystery that continues to intrigue and challenge astronomers and SETI enthusiasts. Although many attempts have been made to re-detect the signal or to find a plausible explanation for its origin, none of them have been conclusive or widely accepted.
One of the most recent and controversial studies was conducted by Antonio Paris, an astronomer and former analyst of the U.S. Department of Defense, who suggested that the signal was most likely generated by a comet passing by Earth. Paris and his team identified two comets, 266P/Christensen and P/2008 Y2 (Gibbs), that were in the same region of the sky as the Wow! signal in 1977, but were not discovered until later. They proposed that these comets could have emitted radio waves at 1420 MHz due to the presence of hydrogen molecules in their tails.
To test this hypothesis, Paris and his team observed these comets and three others with a 10-meter radio telescope between November 2016 and February 2017. They found that all of them had a strong signal at 1420 MHz, and that the peak intensity of Comet 266P/Christensen matched the Wow! signal. They also found that when they moved the telescope away from the comets, the signal disappeared.
Paris and his team concluded that their results provided strong evidence that the Wow! signal was a natural phenomenon caused by a comet, and not a message from an alien civilization. However, their study has been criticized by other astronomers and SETI experts, who pointed out several flaws and inconsistencies in their methodology and analysis.
Some of the main criticisms are:
The original Wow! signal was much stronger than the signals detected by Paris and his team from the comets. Paris explained this by assuming that the comets had lost mass over time, but did not provide any quantitative estimates or calculations to support this claim.
The original Wow! signal was very narrowband, meaning that it had a very precise frequency of 1420.4556 MHz, while the signals detected by Paris and his team from the comets were much broader, spanning several megahertz. Paris did not explain how a natural source could produce such a narrowband signal.
The original Wow! signal lasted for 72 seconds, which was the maximum duration that the Big Ear telescope could observe any given point in the sky. However, the signals detected by Paris and his team from the comets lasted for much longer, up to several hours. Paris did not explain why the comets would produce such a short-lived signal in 1977, but not in 2016 or 2017.
The original Wow! signal was never detected again, despite repeated observations of the same region of the sky by Ehman and others. However, if the signal was caused by a comet, it should have been detectable for days or weeks as the comet moved across the sky. Paris did not explain why no one else observed the comets or their signals in 1977.
Therefore, many astronomers and SETI experts remain unconvinced by Paris’ explanation, and consider it unlikely or implausible. They argue that there is still no satisfactory natural or artificial source for the Wow! signal, and that it deserves further investigation and scrutiny.
Conclusion
The Wow! signal is one of the most intriguing and mysterious events in the history of astronomy and SETI. It has sparked many debates and speculations about its origin and meaning, but has also inspired many people to wonder about the possibility of life beyond Earth.
Although many attempts have been made to explain or reproduce the signal, none of them have been definitive or convincing. The Wow! signal remains an open question that challenges our understanding of nature and our place in the universe.
Perhaps one day we will find out what caused it, or perhaps we will never know for sure. Until then, we can only keep looking up at the stars and listening for more signals that may reveal something new and unexpected about our cosmic neighbors.
