The WOW Signal

Was it a contact from other life forms out there?  Was it a satellite or spacecraft?  Or was it a computer glitch?  The WOW signal still continues to create intrigue to this day.  It is coming up to the 35th anniversary of its discovery so I decided to find out a little bit more about this mysterious signal.

August 15, 1977 may be etched into the minds of some people, it was the night before Elvis Presley died, but it was also the night that a signal from space was detected.  Uncovered by Jerry Ehman, the WOW signal was a strong narrowband radio signal.  Ehman was part of the SETI (Search for Extraterrestrial Intelligence) project working at the Big Ear radio telescope at Ohio, USA at the time.

The Big Ear telescope was in operation from 1971 until it was demolished in 1998 to make way for a golf course.  In 1973, the Big Ear began to search for radio signals originating from somewhere other than Earth and outside of our Solar System.This deep sky survey ended in 1995 which happens to make it the longest running SETI project in history.  The scientists at the Big Ear Observatory even received recognition for this achievement by making it into the Guinness book of records.

The signal, which lasted 72 seconds came from the direction of the constellation Sagittarius (and towards the packed together stars of the galactic core), and has never been detected since.  At the time it was difficult to tell where the signal had come from as there was a delay between the message arriving, and it being discovered on the printout.  Once found, it became known as the “WOW signal” after Ehman circled the signal and wrote the word “WOW!” beside it.  Beside the word “WOW” you will noticed these six characters circled as well, this is the most compelling evidence yet of technological life out there!

The famous WOW signal on paper Credit- Wikipedia


But to us, this code is just a series of letters and numbers so let’s look deeper into its meaning.

The series “6EQUJ5” described the strength of the received signal over a short time-span. Each number from 1 to 9 represented the signal level above the background noise.  The letters represent a scale extension, with each one from A to Z representing increasingly stronger signal levels. 6EQUJ5 represented a signal that grew in strength to level “U”, and then gradually subsided. In numeric terms, the signal increased from zero to level 30 “sigmas” above the background noise, and then decreased again to zero.

On first analysis it appeared to be an artificial radio signal rather than a natural radio emission such as a pulsar or quasar.  Using a receiver with 50 radio channels the Big Ear only heard the signal on one frequency, with no noise on any of the other channels.  It happens that a natural emission would cause static to appear on all of the frequencies, and this was not the case.  The signal was also narrow and focused, as would be expected from an artificial source.

A possible explanation could have been a transmission from a satellite.  However the fact that it was not observed again does not help this theory as an orbiting satellite would normally broadcast  its signal repeatedly. Nor were any planets or asteroids in the vicinity, even if they were radio transmissions would not be expected to come from them.  Similarly there were no spacecraft in that area of space, but if there had been, none would have been transmitting around the 1420MHz that the message was received at.

Many people believe that it couldn’t have been a signal from a distant planet because surely they would have sent more than just one.  But let’s think about it, we sent out a message into outer space in 1974.  It was sent using the Arecibo telescope and it was only sent the once!  The Arecibo telescope is 1000ft in diameter and is based in Puerto Rico.  It was aimed at the globular star cluster M13 which is 2 ,000 light years away and the message lasted a mere three minutes.  If you have seen the film “Goldeneye” then you have seen this huge structure as it features in the climax at the end between Sean Bean and Pierce Brosnan’s characters.

The Arecibo Telescope Credit- Wikipedia


Through the years, as equipment advanced and capabilities improved the search for the signal continued.

In 1987 and in 1989, Astronomer Robert Gray, searched againfor this mysterious voice from the sky, but didn’t find any trace.  Gray, using the Very Large Array, tried again in 1995 and 1996, but he did not have any luck finding a signal.  In 1999 he tried again alongside Dr. Simon Ellingsen, using the University of Tasmania’s Hobart 26m radio telescope in six 14-hour observations, but detected nothing.

Graph showing signal strength versus time Credit- Wikipedia

(Article by Sinead McNicholl)