Since the days of the space race, humans have been actively listening to the skies in hope of stumbling upon otherworldly transmissions that would provide an unequivocal answer to the all important question: "are we alone in the Universe?"
Our nearby celestial neighborhood is eerily quiet as astronomers continually traul through the heaps of data that may contain evidence of intelligent extraterrestrial life.
However, in 1977, a strong radio frequency was detected by the Big Ear radio telescope in Ohio. So unusual was this transmission that the decoding astronomer, Jerry R. Ehman, wrote the exclamation "Wow!" next to it, because it fitted the criteria for extraterrestrial origin.
The recording of the signal lasted 72 seconds - the entire window that the telescope could observe it for.
Initially, Ehman was skeptical about it being artificial, originating from extraterrestrial life: "We should have seen it again when we looked for it 50 times. Something suggests it was an Earth-sourced signal that simply got reflected off a piece of space debris."
Later, he backtracked on this statement after further research made it very unlikely to have originated from Earth. It was found to use a frequency inside the "protected spectrum" that Earth-bound transmitters cannot use, because it's reserved for astronomical purposes.
Scientists claim that the signal was so powerful, if it had come from extraterrestrials, it would have been from an extremely advanced civilization, as it would have required a transmitter that's significantly more powerful than any that we can currently build with our current or near-future technology.
Unfortunately, subsequent searches around the location of the original signal have so far proven fruitless. Perhaps one day, it will be detected and recorded once more with updated techniques and modern technology that'll give us a better understanding of the mysteries surrounding the signal that continues to both intrigue and perplex many who study it.