Wow! signal
There are a number of hypotheses as to what the Wow! signal is, and where it came from. Scientists have not gotten behind any one of these ideas. Interstellar twinkling of a weaker signal—similar in effect to twinkling of stars in the sky—could be an explanation, but that would not exclude the possibility of the signal being from extraterrestrials. The significantly more sensitive Very Large Array did not detect the signal, and the probability that a signal not detected by the Very Large Array could be detected by the Big Ear due to interstellar twinkling is low. Other hypotheses include a rotating lighthouse-like source, a signal sweeping in frequency, or just a one-time event.