The Wow! Signal deciphered—it was hydrogen all along, study says
In 1977, astronomers received a powerful, peculiar radio signal from the direction of the constellation Sagittarius. Its frequency was the same as neutral hydrogen, and astronomers had speculated that any ETIs attempting ...
But what was it?
Beginning in the 1970s, the Ohio State University Big Ear radio telescope was used in the university's Search for Extraterrestrial Intelligence (SETI) program, which ran from 1973 to 1995. This program is the longest-running SETI program in history.
In 1977, Big Ear detected the peculiar signal that's taken on a life of its own. The Wow! Signal was a strong narrowband radio signal right near the frequency of neutral hydrogen. The Big Ear telescope is long gone now, but the effort to understand what the signal is lives on.
The signal lasted the full 72-second window in which Big Ear was able to observe it. A few days later, astronomer Jerry R. Ehman was looking over the data when he saw the signal on a computer printout. Astronomers had never seen anything like it, and he wrote "Wow!" beside it, and the name has stuck ever since.
The signal has another name: 6EQUJ5. This has been interpreted as a message hidden in the signal, but it really represents how the signal's intensity varied over time.
The signal generated a lot of excitement. Some thought it was extraterrestrial in origin, some thought it could come from some type of human-generated interference, and some thought it could be from an unexplained natural phenomenon.
New research shows that the Wow! Signal has an entirely natural explanation.
The research is titled "Arecibo Wow! I: An Astrophysical Explanation for the Wow! Signal." The lead author is Abel Méndez from the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo. It's available on the preprint server arXiv.
The Wow! signal from 1977 as discovered by astronomer Jerry R. Ehman. Credit: Big Ear Radio Observatory and North American AstroPhysical Observatory
This image is a plot of the Wow! signal’s intensity versus time. Credit: Maxrossomachin – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=16197844
This simple schematic shows how the Wow! Signal was generated and detected. A radiative source such as a magnetar or a soft gamma repeater is positioned behind a cloud of cold neutral hydrogen. Energy from the source stimulates emission from the HI cloud, which brightens abruptly and is observable from Earth. Credit: arXiv (2024). DOI: 10.48550/arxiv.2408.08513