Astronomy Fun Fact #56
When Jocelyn Bell Burnell first discovered the first pulsar in 1967, people thought she had detected a signal from aliens. No one knew what else could create such regularly spaced quick pulses of electromagnetic radiation. So Burnell named the signal "Little Green Men."
The theory was abandoned when astronomers detected a similar pulse pattern coming from a different part of the sky. Now we know that those pulses are created by pulsars - super dense neutron stars that periodically send us flashes of bright light as they rotate, kind of like a lighthouse's spinning beacon.