The Wow! signal
A 72-second radio anomaly that remains unexplained.
On August 15, 1977, Ohio State University’s Big Ear radio telescope—then dedicated to the search for extraterrestrial intelligence—picked up a strong, narrowband radio signal. The burst seemed to originate from the constellation Sagittarius and matched several traits expected of an artificial, non-human source. A few days later, volunteer astronomer Jerry R. Ehman spotted the anomaly while manually reviewing computer printouts. He circled the intensity reading “6EQUJ5” and scrawled “Wow!” in the margin, giving the event its famous nickname.
The signal lasted exactly 72 seconds, the full observation window of the Big Ear telescope. Despite repeated follow-up attempts and various hypotheses—including reflections from space debris, interstellar scintillation, or comet hydrogen clouds—the signal never repeated, and no confirmed explanation (terrestrial or otherwise) has emerged. Some researchers still consider it a possible extraterrestrial transmission, but its singularity and lack of replication weaken that case. The Wow! signal has spurred targeted searches, scientific debate about rare astrophysical phenomena, and appearances in popular culture.
**Background** In 1959, physicists Philip Morrison and Giuseppe Cocconi proposed that an alien civilization trying to communicate by radio might use the 1420 MHz frequency (the 21-centimeter hydrogen line), since hydrogen is the universe’s most common element and would likely be known to any advanced society. In 1973, after finishing a broad survey of extragalactic radio sources, Ohio State University assigned its now-defunct Big Ear observatory—located near the Perkins Observatory on the campus of Ohio Wesleyan University in Delaware, Ohio—to SETI work, making it the longest-running program of its kind. By 1977, Ehman was a volunteer analyzing data processed by an IBM 1130 computer and printed on line paper. While examining data from August 15 at 22:16 EST (23:16 EDT, 03:16 UTC), he found a striking sequence of intensity and frequency values that astonished him and his colleagues. The observatory’s director later documented the event in technical detail.
**Signal Measurement** The string “6EQUJ5” is often mistaken for a coded message, but it actually represents the signal’s intensity variation over time, using the experiment’s specific measurement system. The signal itself appeared to be an unmodulated continuous wave, though any modulation with a period shorter than 10 seconds or longer than 72 seconds would have been undetectable.
**Intensity** Intensity was measured as a signal-to-noise ratio, with the noise baseline averaged over the previous few minutes. The signal was sampled for 10 seconds, then processed by the computer for 2 seconds. Each frequency channel’s result was printed as a single alphanumeric character: a space meant an intensity between 0 and 1 (baseline to one standard deviation above it); numbers 1 through 9 indicated corresponding intensities; intensities of 10 or higher used letters (A for 10–11, B for 11–12, etc.). The Wow! signal’s peak value was “U,” meaning an intensity between 30 and 31—thirty standard deviations above background noise.
**Frequency** In a 1994 summary for Carl Sagan, observatory director John Kraus gave the signal’s frequency as 1420.3556 MHz. Ehman, however, reported 1420.4556 ± 0.005 MHz in 1998—about 50 ± 5 kHz above the hydrogen line (1420.4058 MHz). If due to blue-shift, that would imply the source was moving roughly 10 km/s toward Earth. The discrepancy between Kraus’s and Ehman’s values stems from a purchasing error: the telescope’s first local oscillator was ordered at 1450.4056 MHz, but the university’s purchasing department typed 1450.5056 MHz instead (0.1 MHz higher). The software was written to correct for this mistake, and Ehman accounted for it when calculating the signal’s frequency.
**Bandwidth** The Wow! signal had a bandwidth of less than 10 kHz, making it a narrowband emission with a fractional bandwidth of about 0.001%. However, 10 kHz is not especially narrow compared to some astrophysical masers (~1 kHz) or modern SETI searches (~1 Hz). Big Ear’s receiver measured fifty 10 kHz-wide channels; the signal appeared almost entirely in a single column of the printout.
**Time Variation** At the time, Big Ear could only adjust its altitude (height above the horizon), relying on Earth’s rotation to scan the sky. Given Earth’s rotation speed and the telescope’s observation window, any given point in the sky remained in view for 72 seconds—exactly the duration of the Wow! signal.
- known_for
- Strong narrowband signal of possible extraterrestrial origin, never replicated
Lore & Background
The Wow! The telescope relied on Earth's rotation to scan the sky, and the signal lasted the full 72-second observation window, showing a gradual increase and decrease in intensity consistent with a continuous source. Astronomer Jerry R. He circled the intensity sequence '6EQUJ5' and wrote 'Wow!' on the printout. The signal's intensity peaked at 'U', representing a signal-to-noise ratio of 30 to 31. The signal's bandwidth was less than 10 kHz, and it appeared in only one of the telescope's two feed horns, leaving two possible right ascension coordinates. The declination was unambiguously determined, placing the source in Sagittarius, about 19° southeast of the galactic plane. Despite numerous follow-up searches and hypotheses—including reflections from space debris, interstellar scintillation, and comet hydrogen clouds—the signal has never recurred, and no explanation has been confirmed.
Reader's Guide
The Wow! signal remains one of the most tantalizing anomalies in the search for extraterrestrial intelligence. Its strength—30 standard deviations above noise—and narrowband nature near the hydrogen line made it a compelling candidate for an artificial transmission. However, its single occurrence and lack of replication limit the strength of this interpretation. The signal has inspired targeted searches, scientific discussion about rare astrophysical phenomena, and references in popular culture. The uncertainty in its origin—whether due to a natural astrophysical process, a terrestrial interference, or an extraterrestrial beacon—remains unresolved. The Wow! signal continues to serve as a benchmark for the field, illustrating the challenges of confirming a one-time event and the enduring human curiosity about life beyond Earth.
Did You Know?
- The signal's intensity string '6EQUJ5' is not a message but represents signal-to-noise ratios: 'U' indicates a signal-to-noise ratio between 30 and 31.
- The Big Ear telescope could observe any given point for only 72 seconds due to Earth's rotation, and the Wow! signal lasted exactly that duration.
- The frequency of the signal was about 50 kHz above the hydrogen line, which if due to blue-shift would correspond to a source moving about 10 km/s toward Earth.
A Lifeline Forged in Grief
He later described writing most of the material in the raw aftermath of the split, calling the process a catharsis and a lifeline that simply poured out of him. Yet the album was not a solitary exercise. After years of self-producing, Bellamy consciously stepped back, inviting touring member Dan Lancaster to shape eight of the ten tracks and Aleks von Korff to helm two. Bellamy, who admitted the band members were control freaks resistant to outside direction, said Lancaster nonetheless pushed them toward a fresher, more modern palette. He also credited Coldplay's Chris Martin with nudging him toward greater collaboration, a shift that ultimately made the record feel, in his own words, the easiest Muse album to create.
A Cosmic Concept Built on Grief and Wonder
The Wow! Signal is structured as a concept album orbiting the idea of cosmic mystery and the possibility of reaching out to something vaster than ourselves. For Bellamy, that signal doubled as a metaphor for his own emotional journey through the five stages of grief after his divorce, and it also pointed toward his ambivalence about artificial intelligence, which he believes will eventually illuminate things humanity does not yet comprehend. Musically, critics framed the record as a return to the guitar-forward, orchestral ambitions of Muse's early-2000s peak while layering in the electronic beats of The 2nd Law and the eight-string heaviness of Will of the People. Reviewers from AllMusic, The Guardian, Rolling Stone, and The Irish Times noted influences spanning Queen, Korn, Radiohead, and seventies arena rock, describing the result as a cohesive, less melodramatic statement that extracts the band's core DNA rather than imitating it.
Voices Beyond the Band
Although Muse had never before invited an outside singer onto a track, "Hush" broke that tradition when Ellie Goulding, who happened to be working in the same studio, was asked to contribute vocals. Bellamy recalled that the moment she sang, the song simply became a duet, and within an hour and a half the finished recording was in the can. The album also weaves in the voices of Bellamy's own children: his son Bingham handles percussion on the sprawling opener "The Dark Forest," while his daughter Lovella sings in a children's choir on the disco-flecked "Nightshift Superstar," a track Bellamy dedicated to the early, party-loving days of his relationship with Evans. Bellamy has spoken openly about how Lancaster, despite the band's well-known resistance to outside direction, functioned almost as an additional member, steering the group toward a sound he described as fresh and modern.
From Space to Stadiums
Muse's promotional campaign for The Wow! Signal was as theatrical as the music itself. A small, intimate set at London's Brixton Academy in April served as the debut stage for "Cryogen," which followed as the third single in late April. "Hexagons" and "Nightshift Superstar" rounded out the single cycle in May and early June before the full album dropped on 26 June through Warner Records and Helium-3. A North American leg of the tour launched in July, with a European arena run scheduled to follow in November.
Frequently Asked Questions
How did the Wow! signal get its name?
A few days after the detection, graduate student Jerry R. Ehman was scrolling through the telescope's printed data and spotted an intensity reading of '6EQUJ5' that stood out dramatically. He circled the figure and scribbled 'Wow!' in the margin, and that casual annotation became the event's permanent nickname.
Why does the Wow! signal matter to the search for extraterrestrial life?
It remains the single strongest candidate for a technosignature ever recorded, which makes it a touchstone for every SETI discussion about what a real contact might look like. Even without a repeat detection, it shaped how the field designs its instruments, sets its false-alarm thresholds, and frames the public conversation about whether we are alone.
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