🇺🇸 United StatesThe Wow! Signal
The Story
On August 15, 1977, astrophysicist Jerry R. Ehman was reviewing computer printouts from Ohio State University's 'Big Ear' radio telescope. He discovered an extraordinarily intense, narrow-band wireless transmission that lasted for the full 72-second window the telescope could track. The signal peaked precisely at the 1420 MHz hydrogen line frequency, an internationally protected interstellar channel. Ehman circled the data sequence '6EQUJ5' and wrote 'Wow!' in the margin, initiating a major space anomaly.
Images
Timeline
The Big Ear radio telescope logs the intense narrow-band transmission during an automated sky survey sweep.
Jerry Ehman discovers the anomalous data printout while conducting routine performance audits of the log batch.
The Center for Planetary Science publishes a controversial counter-hypothesis attributing the radio source to passing cometary bodies.
Known Evidence
How well-documented and physically verified the case evidence is.
- The original computer data matrix output recording the sequential intensity codes '6EQUJ5', proving a non-random, targeted power curve.
- The signal's transmission profile confirming a highly localized, narrow-band bandwidth of less than 10 kHz, distinct from standard natural cosmic noise.
- A transmission frequency calibrated precisely to 1420.405 MHz, matching the natural astronomical emission line of neutral hydrogen gas.
- The systematic 72-second signal duration, matching the exact geometrical scanning beam window of the Big Ear telescope's dual horns.
Unresolved
What We Still Don't Know
- The exact point source or cosmic origin coordinates within the constellation Sagittarius, with follow-up sweeps yielding zero signal replication.
- The technical design or mechanical nature of the transmitter capable of focusing a high-energy narrow-band signal across interstellar distances.
- The complete lack of any embedded modulation, data packets, or recognizable structural code sequences within the captured intensity peaks.
Hypotheses
Theories
Ranked by plausibility — highest first.
Extraterrestrial Technological Transmission
The signal was a deliberate, artificial deep-space transmission broadcast by an intelligent extraterrestrial civilization utilizing a highly focused, transient radio beacon aimed toward the solar system.
Transient Cometary Hydrogen Cloud Outgassing
The radio burst was a natural phenomenon caused by the undetected transit of two ancient comets (266P/Christensen and P/2008 Y2). The vast, diffuse neutral hydrogen clouds enveloping the comets emitted a brief 1420 MHz signal as they passed through the telescope's focus.
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