Delving into the Vast Abyss: Fifteen Unsolved Mysteries in Science that Leave Experts Scratching Heads

The Wow! Signal

In 1977, a radio telescope detected a strong signal from space that lasted for 72 seconds. Named the Wow! signal after the note written by the astonished astronomer, it remains the strongest candidate for an alien radio transmission ever detected. Despite numerous attempts, the signal has never been detected again, leaving its origin a mystery.