The "Wow" signal has been identified

 For decades, scientists and UFOlogists alike have puzzled over the "wow signal," which was captured by astronomer Jerry Ehman in 1977. He was so surprised by the signal that he wrote "Wow!" on the margins of the print-out, thus inadvertently naming it for all posterity. 

The signal lasted for the entire 72 seconds that the Big Ear radio telescope was pointing at it. The telescope, on an automated sweep of the sky, passed on after 72 seconds, and the signal was never heard from again. Due to the nature of the signal, many experts have considered it the strongest possible evidence for the existence of extraterrestrials.

Until now.

A peer-reviewed paper by astronomer Antonio Paris was just published. It identifies the "Wow" signal beyond a reasonable doubt as belonging to a comet. This particular comet passed through that segment of sky on that night in 1977. Furthermore, researchers have since found other comets which emit similar signals.

As for what actually caused the signal, the source is unknown, but is theorized to be hydrogen clouds surrounding the comet.

One more answer for astronomy... one less mystery in our skies.