The WOW! Signal

SETI - the Search for Extra-Terrestrial Intelligence - looking for an E.T. radio signal utilising radio telescopes has been going on for a number of years.

This search has been rather intermittent, with frequent, year long pauses due to budget cuts. The Ohio State Big Ear radio telescope, the longest continuously running project, began listening in 1974 and has since completed about 60% of its all-sky search. In 1977, it made history by detecting an extremely strong signal that, after ruling out terrestrial sources and known artificial satellites, it suggested had originated in outer space.

The "Wow" signal [see above, anomalous signal are the circled numbers] - named for a note scribbled on the recorder tape - remains the most intrigueing clue, but it has not been heard again. This year, the Big Ear antenna that picked it up will be torn down.