Astronomers have detected the first-ever radio emissions from the interstellar comet 3I/ATLAS as it passed its closest approach to the sun, confirming natural outgassing activity while firmly debunking unevidenced alien theories promoted by Harvard astrophysicist Avi Loeb.
The interstellar interloper 3I/ATLAS, only the third known interstellar object to cross through our cosmic neighborhood, has generated intense scientific scrutiny and internet speculation since its discovery in early July, although observations dating back to May have since been uncovered.
Speeding toward the sun at more than 130,000 mph (210,000 km/h), the comet reached its perihelion on Oct. 29. Right around that milestone, researchers utilizing South Africa’s MeerKAT radio telescope detected the first radio emissions from 3I/ATLAS. Most researchers agree that it is a comet, potentially the oldest of its kind ever seen, that was catapulted out of an alien star system in the “frontier” region of the Milky Way up to 7 billion years ago.
Natural Outgassing Confirmed by MeerKAT Telescope
While proponents of unverified alien theories expected the signals to reveal a technological origin, astronomers confirmed the emissions stem entirely from natural physical processes. Specifically, the data showed specific wavelength absorption related to the presence of hydroxyl radicals, or OH molecules, in the comet’s coma.
These radicals are formed by the breakdown of water molecules as they are ejected from the comet via a natural process known as outgassing, which is a clear sign of cometary activity, according to a 2016 study. The detection aligns closely with earlier observations from NASA researchers in early October, who spotted water spewing from the comet like a fire hose
on full blast. The latest findings show that this water is being broken down by solar radiation as you would expect during perihelion.
Unexpected Solar Flyby Behavior and Disappearing Tails
The new radio signals were first detected on Oct. 24, shortly after 3I/ATLAS briefly disappeared behind the sun during perihelion. The comet’s solar flyby was also notable for an unexpected brightening event and a temporary color change.
And after reappearing earlier this month, the comet then appeared to have lost its tail, although this turned out not to be true.
Silencing the Extraterrestrial Mothership Claims
Ever since the interstellar interloper was discovered, a small group of scientists — led by Harvard University astrophysicist and renowned alien-hunter Avi Loeb — have been promoting the unevidenced theory that the comet is actually an alien spacecraft in disguise. This has led to a number of misleading stories about the comet, which experts say distracts from the real science surrounding the ISO. (This is similar to what happened to the first-ever ISO ‘Oumuamua, which Loeb and others also labelled as a potential alien mothership.)
The latest radio wave findings thoroughly refute those claims. Loeb acknowledged the detection of the hydroxyl radicals in the latest 3I/ATLAS update on his personal blog, which now has over 100,000 subscribers. However, he did not state whether this was a sign of classic cometary activity or not.
The comet has previously displayed several other anomalous characteristics that have added fuel to the fires of alien conspiracy theorists, including a highly irradiated surface, an overabundance of carbon dioxide and a puzzling anti-tail. However, all of these have been properly explained by the astronomical community.
Clearing Up Confusion Around Comet Borisov
A newly discovered comet, dubbed C/2025 V1 (Borisov), was wrongly linked with 3I/ATLAS, despite having nothing to do with the ISO. It reached its closest point to Earth on Tuesday (Nov. 11).
Tracking Future Interstellar Visitors
As 3I/ATLAS continues its one-way trip through the solar system, right as it passed the halfway mark, researchers are shifting focus toward what future interstellar visitors might reveal. The successful detection of radio emissions proves that sensitive terrestrial instruments can capture faint signatures from objects originating outside our solar system, paving the way for more precise tracking when the next interstellar interloper eventually arrives.