The 72 Seconds We Still Can't Explain

Name: The 72 Seconds We Still Can't Explain
Genre: Documentary

A 72-second burst detected in 1977 leaves behind one cryptic printout and a mystery that remains unidentified.

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Transcript

For the telescope's 72-second window, one unexplained signal filled the recording.
It has never returned, and no confirmed explanation identifies what caused it.
At 11:16 p.m. on August 15th, 1977, Ohio State's Big Ear received it.
Inside, a Big Ear astronomer faced another night of numbers. Keep the survey running.
The receiver captured a strong, narrowband emission near hydrogen's famous radio line.
Six integration periods totaled 72 seconds—the telescope's entire chance to watch.
The signal increased, peaked, and decreased, consistent with a cosmic source fixed on the sky.
For those seconds, the sky looked less empty than before.
Normally, a fixed source crossed one beam, then the other 72 seconds later.
But this signal appeared in only one beam, with nothing matching in the other.
At its peak, “U” registered between 30 and 31 standard deviations above background noise.
Days later, volunteer astronomer Jerry Ehman reviewed IBM-processed data on line-printer paper.
Across six measurements, the printer produced one sequence in channel two: “6EQUJ5.”
Wow!
That handwritten reaction became the name of a signal still unidentified today.
Later searches listened for 14 hours across multiple days—and found nothing resembling it.

The entire mystery seemed locked inside six characters—“6EQUJ5”—but what did that code actually mean?

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