It was on August 15, 1977, that Ohio State University’s Big Ear radio telescope received what many consider to be the most convincing scientific argument of extraterrestrial life — a signal from outer space. Discovered by astronomer Jerry R. Ehman when reviewing data, the 72-second event came from somewhere around the Sagittarius constellation. To this day, there is no agreed-upon explanation for what the telescope received, with opponents of the alien life theory suggesting natural phenomena or even a human-made source. It was on August 18 that the event would get its most widely known name, Ehman writing “WOW!” in the margins of computer printouts next to the letters “6EQUJ5”. Ehman was at the time a professor at Ohio State and also volunteered with SETI, the Search for Extraterrestrial Intelligence. He knew what to look for.
Scientists had long believed that the first confirmation of alien life would come in the form of radio signals. The physicists Philip Morrison and Giuseppe Cocconi of Cornell University suggested that radio waves would be the first indications of a civilisation that would be observable across a galaxy. A 1959 paper by the pair speculated that should any such society be deliberately trying to contact other life, they would do so on a frequency of 1420 megahertz (21 centimetres), being naturally emitted by hydrogen, the most common element in the universe. Knowledge of this would indicate an understanding of mathematics and chemistry.
The August 15, 1977 data from 22:16 EDT (03:16 GMT) seemingly showed a radio signal had been transmitted at 1420.4556 MHz. As expected by Morrison and Cocconi, the event was loud, with the “6EQUJ5” lettering showing the intensity of the electromagnetic signal as it hit the receiver at Big Ear. Low power was recorded by numbers, and as strength increased, the computer would record higher intensity with letters. The letter U is the 21st letter in the alphabet, indicting a staggering amount of intensity had been received by the dish, as much as 30 times louder than the typical noise of space. The radio telescope was only adjustable for altitude and relied on the rotation of the planet to scan across the skies. This meant that given Earth’s speed, any given point would only be observed for 72-seconds. A continuous signal from alien life would therefore be expected to last for the entire 72-seconds from any given moment, increasing for the first 36 seconds and then peaking at the centre of the window. Such a signal would then decrease for 36 seconds as the telescope moved away. The WOW! Signal showed precisely that.
Scientists at SETI immediately set about trying to locate the origin of the signal, tracing it to Sagittarius, slightly north-west of globular cluster M55. However, intriguingly there was no planet or star at this location, only open space. While the possibility exists that the signal came from a moving object such as a spacecraft, the lack of an identifiable origin raised the question as to whether the noise had been from a civilisation at all. While many theories have been proposed, none have gained widespread consensus in the scientific community.
The fact that the signal was never heard again despite many attempts puzzled researchers, with it unlikely that a deliberate alien signal would only be transmitted once. Equally, this would seem to also discount many theories that it was a natural phenomenon, unless it had been a singular and possibly unique event. Yet, scientists regularly discover new wonders in space, colliding black holes, glitching pulsars, and gamma-ray bursts being among the many discoveries noted for their loud and unusual noise. One theory suggested as to the origin of the signal was that the real source was actually on Earth itself, simply being reflected back at the planet off space debris. Scientists at SETI investigated the theory at length. They concluded this to be highly unlikely as the 1420 MHz spectrum is protected for use by astronomic facilities, meaning no domestic usage is allowed. Equally, the requirements for a signal to be bounced back so effectively are highly unlikely.
Teams at SETI also discounted the possibility of a satellite transmission, aircraft signals and broadcast beams. The mystery has persisted until this very day, with a 2017 theory by Antonio Paris, a teacher from Florida, being equally dismissed. Paris had speculated that the signal had been hydrogen from a cloud surrounding two comets that were known to be in the sky at the time. However, scientists and members of the original SETI team debunked the theory, stating that the comets hadn’t been in the beam at the right time and that they cannot have possibly emitted at the strength observed.
Researchers have long attempted to receive the signal a second time, with Ehman searching for months afterwards using Big Ear. His efforts were in vain, however. Ten years later in 1987 and again in 1989, the astronomer and data scientist Robert H. Gray used the META array at Oak Ridge Observatory to also try and find the signal, similarly to no result. Other attempts were made in 1995, 1996 and 1999, but nothing like the WOW! Signal was ever heard again.
In 2012, scientists finally formulated a “response” to the signal, beaming a collection of 10,000 Twitter messages and videos from celebrities back into space to serve as a “hello” to any alien culture that might be scanning the skies in the same way that humanity is. The project was directed by the National Geographic Channel and the Arecibo Observatory.
With no repeat of the signal ever being heard, the scientific method collapses. Other scientists are unable to verify the data independently, leaving many questions unanswered surrounding its origin and nature. The signal, therefore, becomes a singular aberration. While it may indeed be the first communication from an alien civilisation, there is no evidence to suggest this is the case. Equally, however, there is no evidence to suggest it was not. With no conclusions being drawn as to its true nature, the WOW! Signal remains one of the infinite mysteries of the cosmos.
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