Scientists may have finally solved the mysterious source of the "Wow!" signal discovered 40 years ago.

The Ohio State University Radio Observatory found the radio transmission in the Sagittarius constellation in August 1977. Since the signal was so strong, scientists were inspired to write the "Wow!" in the margin of the data printout. When the signal was first spotted, the Ohio State's "Big Ear" observatory was looking for some evidence from extraterrestrial civilizations.

Like Us on Facebook

Based on the previous research of earlier astronomers, a message of intelligent should be transmitted at a frequency of 1,420 MHz - electromagnetic frequency of hydrogen. The Big Ear, on the other hand, must "hear" it for about 72 seconds considering how long the observatory, particularly in focusing specific point in space.

The "Wow!" signal was the first and the only one that exactly met those criteria. As the finding excites scientists, they tried other trained instruments on that region of space but the mysterious signal never happened and recorded again.

Now, after 40 years, the research team from the Center for Planetary Science solved the mysterious source of the "Wow!" signal. A new hypothesis was proposed by the researchers last year, saying that the culprit might be comets and the frequency is likely due to the hydrogen cloud they carry, not from alien civilizations.

The Comets P/2008 Y2 (Gibbs) and 266/P Christensen seem to have been transiting within the region where the "Wow!" signal was spotted, but they were not identified until after 2006. The team tested their hypothesis and produced 200 radio spectrum observations from November 2016 until February 2017.

The 266/P Christensen transmitted a frequency of 1,420 MHz. To double check the finding, they moved the radio telescope by one degree, the signal suddenly disappeared and returned when trained back on the comet.

To prove that 266/P Christensen isn't an anomaly, the team also probed other three comets; P/2016 J1-A (PANSTARRS), 237P/LINEAR, and P/2013 EW90 (Tenagra). Researchers have found that all of them transmit signals with the equal frequency.

Either the "Wow!" signal was produced by 266/P Christensen or other comets, scientists believed that they have finally solved its mysterious source.