Nearly half a century after it stunned astronomers, the mystery of the Wow! Signal might finally have a potential explanation. Harvard scientist Avi Loeb suggests that the interstellar comet 3I/Atlas could have been the origin of the famous radio signal detected in 1977.
What Was the Wow! Signal?
On August 15, 1977, astronomer Jerry R. Ehman was monitoring the skies with Ohio State University’s Big Ear radio telescope when he noticed a strange spike in radio waves. So unusual was the signal that he scribbled “Wow!” on the printout—giving the phenomenon its name.
The signal, lasting just 72 seconds, appeared to come from the constellation Sagittarius, specifically from sky coordinates: Right Ascension (RA) = 19h25m (291 degrees) and Declination (Dec) = -27 degrees. Despite decades of searches, the Wow! Signal remains unexplained.
Avi Loeb’s 3I/Atlas Hypothesis
In a recent blog post, Avi Loeb proposed that 3I/Atlas, an interstellar comet, might have been responsible. Loeb calculated the position of the comet in 1977 and found it was remarkably close to the coordinates of the Wow! Signal.
- Separation from signal: Approximately 4 degrees in RA and 8 degrees in Dec.
- Chance of random alignment: About 0.6%, indicating a very low likelihood that this alignment was coincidental.
- Distance from Earth in 1977: Around 600 astronomical units (AU), roughly 600 times the distance between Earth and the Sun.
Loeb concluded that if 3I/Atlas was indeed the source, the comet may have emitted radio waves with power between 0.5–2 gigawatts—comparable to a typical nuclear reactor on Earth.
Why This Matters
If confirmed, this would suggest that interstellar objects can emit detectable radio signals, a finding with implications for astronomy and the search for extraterrestrial intelligence (SETI). Loeb hopes that this coincidence will encourage further study into whether 3I/Atlas exhibits any radio transmission today.
“Understanding whether 3I/Atlas could generate radio signals might help us unlock new knowledge about interstellar objects and even the possibility of technological activity beyond our solar system,” Loeb wrote.
Where Is 3I/Atlas Now?
3I/Atlas is currently traveling through our solar system at a staggering speed of 221,000 km/hr (about 60 km/s). Over the next few days, the comet will pass near Mars, giving astronomers a rare opportunity to observe it up close.
- Observation dates: October 3
- Instruments:
- ESA’s Trace Gas Orbiter (TGO) with the CaSSIS camera
- Mars Express with the High Resolution Stereo Camera (HRSC)
These observations will help scientists capture detailed images of the comet and potentially investigate any unusual activity, including radio emissions.
The Wow! Signal Remains a Mystery
Despite numerous theories over the decades—from extraterrestrial transmitters to natural cosmic phenomena—the Wow! Signal has defied a definitive explanation. Recent studies suggest the signal was much stronger than previously thought, with an intensity range of 54–212 Jansky and a bandwidth of about 10 kHz.
Loeb’s hypothesis adds a fresh perspective, linking an interstellar object to a rare astronomical event. Whether 3I/Atlas truly emitted the Wow! Signal remains unproven, but the possibility is exciting for astronomers and SETI enthusiasts alike.
TL;DR
Avi Loeb suggests that the interstellar comet 3I/Atlas may have been the source of the Wow! Signal detected in 1977. Calculations indicate the comet’s position aligns closely with the signal’s coordinates, with less than a 1% chance of coincidence. As 3I/Atlas approaches Mars, upcoming observations may provide new insights into this long-standing astronomical mystery.