Most people have seen the printout. Almost nobody actually understands what the characters mean.

On August 15, 1977, astronomer Jerry Ehman circled a sequence of characters on a computer printout from Ohio State University's Big Ear radio telescope and wrote "Wow!" in the margin. That sequence was 6EQUJ5. It became the most famous string of characters in the history of SETI.

But here's the thing — those aren't arbitrary codes. They're signal-to-noise ratios encoded in a single-character system, and once you understand the encoding, the entire signal snaps into focus.

The Encoding System

The Big Ear's computer printed one character per channel per observation cycle. The encoding worked like this:

• Blank space = SNR between 0.0 and 0.99 (noise floor)

• 1–9 = SNR of 1.0–9.99 (digits map directly)

• A–Z = SNR of 10.0–35.99 (A=10, B=11, ... Z=35)

So each character in 6EQUJ5 represents a signal-to-noise ratio in one of the telescope's 50 frequency channels, measured over a 12-second integration window.

Breaking Down 6EQUJ5

The "U" is the peak — a signal-to-noise ratio of at least 30x above the background noise. For context, most radio astronomy sources produce SNRs in the low single digits.

Why the Shape Matters

When you plot these values, they form a near-perfect Gaussian curve — a smooth bell shape that rises, peaks, and falls symmetrically. This is exactly what you'd expect from a point source (like a distant transmitter or a star) passing through the telescope's beam as the Earth rotates.

The Gaussian shape tells us two critical things:

1. The source was spatially unresolved — it looked like a point, not an extended object

2. The signal intensity matched the telescope's beam pattern almost perfectly

This is what separates the Wow! signal from terrestrial interference. Local RFI (radio frequency interference) doesn't produce clean Gaussians because it doesn't transit through the beam the same way a celestial source does.

The Question Nobody Asks

Here's what most popular accounts leave out: the Big Ear had two feed horns, separated by about 3 minutes of sky. Any celestial source should have appeared in both horns, producing two Gaussian peaks separated by ~3 minutes.

The Wow! signal appeared in only one.

This is the deepest unsolved problem in Wow! signal analysis, and it's the reason the signal remains genuinely unexplained nearly 50 years later. It's not just that we don't know what produced it — we don't understand why it didn't behave the way any celestial source should have.

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This is the kind of analysis we do in the 30-Day Wow! Signal Analysis Cohort — systematic, data-first, no hand-waving. If you want to actually understand the most famous signal in SETI history, not just know the trivia, the cohort is open now.