In 1977, an astronomer at Ohio State University named Jerry R. Ehman detected a radio signal from space so bizarre he circled it in red and wrote, "Wow!" Since then, many have speculated that the sequence was a message from extraterrestrial life, but experts now believe it's something decidedly less fun — a passing comet.
While searching for signs of extraterrestrial life with the Big Ear radio telescope, Ehman detected a 72-second sequence of extraordinary intensity emanating from the constellation Sagittarius.
Because the signal matched so closely with hydrogen, it was reasoned that extraterrestrials were using it to communicate with us, as the element is the most common in the universe and resonates at a high frequency.
But recently scientists have hypothesized that it came from one or two passing comets releasing a hydrogen cloud as they passed near the Sun.
Specifically, the comets that are the prime suspects are 266P/Christensen and P/2008 Y2.
Both comets were discovered in the past decade, so it's possible that it was their hydrogen discharge which caused Ehman alarm. No one knew what they were back in 1977.
Even scientists are suspicious of this new theory, but we may soon have a definitive answer on where the "Wow!" signal came from, as Comet 266P/Christensen will return to our neck of the solar system at the end of the month and P/2008 Y2 will return in 2018!