Wow! signal
The Wow! signal is a 72-second radio burst an Ohio telescope caught in 1977 while searching for aliens. It never returned, and cold hydrogen clouds emit lookalikes a hundred times fainter.
From 1973 to 1997, Ohio State's Big Ear telescope listened for signals from other civilisations. On 15 August 1977 it caught a strong, narrowband burst near hydrogen's 1420 MHz line. It lasted 72 seconds, as long as any fixed point in the sky took to cross the beam. It sat unnoticed on a printout for about four days. It never returned. One team proposes a cold hydrogen cloud, briefly lit by a flare.
Sources
- Arecibo Wow! II: Revised Properties of the Wow! Signal from Archival Ohio SETI Data (arXiv preprint)
- Arecibo Wow! II, full text (arXiv HTML)
- Arecibo Wow! I: An Astrophysical Explanation for the Wow! Signal (arXiv preprint)
- Big Ear Radio Observatory, Wow! Signal - 30th Anniversary Report
- Big Ear Radio Observatory, The Wow! Signal
- SETI Institute, Green Bank Telescope and Allen Telescope Array observe a possible source of the Wow! signal
- SETI Observations of Exoplanets with the Allen Telescope Array (arXiv)
Pick a question to go deeper.
Read next
- Ion thrustersAn ion thruster pushes a spacecraft with about the force of a sheet of paper resting on your palm. Kept up for years, that whisper outruns any rocket.
- Space-based solar powerSpace-based solar power means collecting sunlight in orbit, where it never gets cloudy, and beaming the energy down to Earth.
- AntimatterAntimatter is the counterpart of ordinary matter, and the two destroy each other on contact. In March 2026, 92 antiprotons were driven around CERN on a truck, and none were lost.
