Wow! Signal

The Definition

A strong, narrowband radio signal detected by astronomer Jerry R. Ehman on August 15, 1977, while working on a SETI (Search for Extraterrestrial Intelligence) project at the Big Ear radio telescope in Ohio. The signal lasted for the full 72-second window that the telescope was able to observe it and has never been detected again, making it the most famous candidate for an artificial radio transmission from another solar system.

The Deep Dive

The "junk knowledge" behind the Wow! Signal is that its name wasn't a scientific designation, but a spontaneous outburst of human emotion. When Ehman reviewed the computer printout a few days later, he was so shocked by the signal's intensity and "perfect" characteristics that he circled the alphanumeric code "6EQUJ5" and scribbled "Wow!" in the margin.

  • The Code (6EQUJ5): This sequence isn't a message; it describes the signal's intensity over time. Big Ear’s computer used a scale of 1–9, then letters A–Z to represent increasing strength. The "U" represents a burst of radio energy over 30 times stronger than the background noise of deep space.

  • The Hydrogen Frequency: The signal occurred at 1420.405 MHz, which is the electromagnetic frequency of hydrogen—the most abundant element in the universe. Astronomers have long theorized that if an alien civilization wanted to "hail" us, they would use this "universal" frequency because it is a natural "quiet spot" in the radio spectrum.

  • The "One-Hit Wonder": Despite hundreds of follow-up attempts using more powerful telescopes, the signal has never returned. This "transience" is the ultimate frustration of the Wow! Signal; in science, a discovery that cannot be replicated is often relegated to the "junk" pile of anomalies, yet the data from 1977 remains impeccably clean.

The Wow! Signal reached peak "junk" status in the pop-culture consciousness as the ultimate "almost" encounter. It represents the "junk" of cosmic timing: the possibility that we finally "picked up the phone" just as the caller hung up, leaving us with a 72-second recording of a dial tone from the stars.

Fast Facts

  • The 72-Second Limit: The signal lasted 72 seconds not because the aliens stopped transmitting, but because the Big Ear telescope was stationary. It relied on the Earth's rotation to sweep across the sky; it took exactly 72 seconds for a single point in space to pass through the telescope's "field of vision."

  • The Comet Theory: In 2017, an astronomer suggested the signal might have been caused by a hydrogen cloud surrounding a passing comet. However, this theory has been largely dismissed by the SETI community, as comets do not produce narrowband signals of that intensity, and the specific comets weren't in the right place at the right time.

  • The Ohio Connection: The Big Ear telescope was located in Delaware, Ohio, on the grounds of Ohio Wesleyan University. Sadly, the telescope was dismantled in 1998 to make room for a golf course, meaning the "ears" that heard the Wow! Signal are now literally part of the junk of history.

References

  • Ehman, J. R. (1977). The Big Ear SETI Observation Report. Ohio State University Radio Observatory.

  • Gray, R. H. (2012). The Elusive Wow: Searching for Extraterrestrial Intelligence. Palmer Publications.

  • The SETI Institute. (2026). The Wow! Signal: 49 Years of Mystery.