The 72-second burst is believed by many to be humanity’s first interception of an alien broadcast, but scientists have been unable to discover anything like it again despite searching for nearly four decades.

Analysis of the data has ruled out satellites as the source, while regulations on Earth do not permit the broadcast of frequencies in the range picked up by Ohio’s Big Ear telescope.

On this date in 1977, the Big Ear telescope receives the Wow! signal from deep space as part of the #SETIproject.

Now, one US scientist believes he may have discovered the culprits which caused the signal - two previously undiscovered comets which passed by earth in 1977.

Antonio Paris, professor of astronomy at St Petersburg College in Florida, says comets 266P/Christensen and P/2008 Y2 (Gibbs) may have emitted enough hydrogen to cause the anomaly.

The two fly-by-night comets were only located by astronomers in the past ten years.

His revelations are shared in the Winter 2016 edition of Journal of the Washington Academy of Sciences.

“I came across the idea when I was in my car driving and wondered if a planetary body, moving fast enough, could be the source,” Paris told New Scientist magazine.

He plans to test his theory by analyzing hydrogen signals from the two comets when they pass earth again in January 2017 and January 2018 respectively.

Some researchers are skeptical about whether comets can produce enough hydrogen to cause a reading on that scale.

Thousands of tweets using the hashtag #ChasingUFOs have been sent into cyberspace including a message from US comedian Stephen Colbert.