Today in Science: August 15th marks the 40th anniversary of the Wow! signal. This famous radio pulse was detected on Ohio State University’s Big Ear radio telescope. It was a very strong 72 second long radio burst. The strength of this signal, along with its length caused scientists to determine that it was unlikely this signal came from Earth, and also had the possibility of not being naturally occurring. This got people considering whether we were alone in the universe. It was though that maybe this provided evidence of alien life.

In recent times it has been suggested that rather than aliens it could have been produced by hydrogen clouds surrounding comets. In the past these have produced similar signals. However, researchers at Big Ear have criticised this theory, stating that no comets were present at the time of the recording.