On 15 August 1977 the Big Ear radio telescope in the US was scanning the skies in a search for signs of intelligent extraterrestrial life. Suddenly, it detected a strong, narrow bandwidth signal that lasted a little longer than one minute – as expected if Big Ear’s field of vision swept across a steady source of radio waves. That source, however, had vanished 24 hours later when the Ohio-based telescope looked at the same patch of sky.

This was the sort of technosignature that searches for extraterrestrial intelligence (SETI) were seeking. Indeed, one scientist wrote the word “Wow!” next to the signal on a paper print-out of the Big Ear data.

Ever since, the origins of the Wow! signal have been debated – and now, a trio of scientists have an astrophysical explanation that does not involve intelligent extraterrestrials. One of them, Abel Méndez, is our guest in this episode of the Physics World Weekly podcast.

Méndez is an astrobiologist at the University of Puerto Rico at Arecibo and he explains how observations made at the Arecibo Telescope have contributed to the trio’s research.