The Wow! Signal

On August 15, 1977, Ohio State University’s Big Ear radio telescope detected a powerful narrowband radio signal from the direction of Sagittarius. Astronomer Jerry Ehman circled the data and wrote “Wow!” - creating one of the most tantalizing mysteries in the search for extraterrestrial intelligence.

The Detection

August 15, 1977:

• Big Ear telescope
• Ohio State University
• SETI project
• Automated recording
• Discovered days later

Jerry Ehman

The astronomer:

• Reviewing data
• Saw the spike
• Wrote “Wow!”
• On the printout
• Historic moment

The Signal Characteristics

What made it special:

• 72 seconds duration
• 1420.456 MHz frequency
• Hydrogen line region
• Where ET would signal
• Expected characteristics

The Frequency

1420 MHz significant:

• Hydrogen emission line
• Universal constant
• “Water hole” frequency
• Where SETI listens
• Logical choice for ET

Signal Strength

The intensity:

• 30 times background
• Strong and clear
• Narrowband
• Not natural?
• Intriguing

Never Repeated

Despite searching:

• Same area scanned
• Multiple times
• Various telescopes
• Never detected again
• One-time event

Natural Explanations

Proposed sources:

• Interstellar hydrogen cloud
• Earth-based interference
• Satellite reflection
• Comet outgassing (2017)
• None confirmed

The Comet Theory

2017 suggestion:

• Comets in area
• Hydrogen emission
• Possible source
• Debated
• Not proven

Problems with Explanations

Researchers note:

• Too strong for natural
• Wrong characteristics
• One-time nature odd
• Doesn’t quite fit
• Mystery remains

The Location

Signal came from:

• Sagittarius constellation
• Near Chi Sagittarii
• About 120 light-years
• If artificial
• Direction known

Continued Interest

SETI still:

• Monitors area
• Hopes for repeat
• Considers significance
• Historic detection
• Benchmark case

Cultural Impact

Wow! Signal became:

• Symbol of SETI hope
• Famous in pop culture
• Referenced widely
• Iconic moment
• Inspiration

Significance

Wow! Signal significant for:

• Perfect SETI characteristics
• Single detection mystery
• Ongoing debate
• Cultural importance
• Historical marker

Legacy

The Wow! Signal remains the strongest candidate for an extraterrestrial radio transmission ever detected. Its failure to repeat keeps the mystery alive, representing both the promise and frustration of the search for extraterrestrial intelligence.