3I/ATLAS, the strange comet that is baffling astronomers and sparking alien theories

The arrival of an interstellar comet is considered an extraordinary event in contemporary astronomy . 3I/ATLAS is striking for its rapid transformation and unprecedented brilliance for objects of this magnitude . Its greenish glow, captured by high-power telescopes , distinguishes it as a body that does not conform to usual patterns.

Discovered in 2024 by the ATLAS system in Hawaii, 3I/ATLAS is the third interstellar visitor , preceding 'Oumuamua (2017) and 2I/Borisov (2019). Each of these discoveries demonstrates that the space between stars is not a static void, but a corridor through which fragments from other latitudes transit.

The anomalies of 3I/ATLAS raise suspicions that it may not be a simple cosmic fragment. Avi Loeb, a renowned Harvard physicist, warns that not everything fits into known categories and proposes a provocative hypothesis: it could be an alien artifact disguised as a comet.

With a nucleus just a few hundred meters across and an unusual coma—the cloud of gas and dust surrounding it—3I/ATLAS generates a lot of suspicion. Observatories such as Gemini North and the Very Large Telescope recorded emissions that defy any equivalence with comets that traverse the Solar System.

Astronomers around the world are closely following its metamorphosis: what seemed like an inconspicuous object has become a true rarity . Its hair grew rapidly and its color turned emerald green, breaking symmetries and forcing a rethinking of cometary dynamics.

The origin of the glow is divided. Some attribute it to compounds such as cyanide and nickel, which, when interacting with solar radiation, emit green light. The ATLAS project team postulates that they are ice grains that reflect light in a unique way. Both hypotheses raise questions about the chemistry of visitors forged beyond the Sun.

Adding to these irregularities is a disconcerting trajectory, with acceleration not solely due to gravitational effects and unusual encounters with Venus, Mars, and Jupiter that keep the mystery open.

Over the weekend, it passed within 2.68 million kilometers of Martian orbit. Although it doesn't pose an immediate threat, Avi Loeb warns that its retrograde inclination—contrary to the flow of the solar system—could pose a danger to our planet .

Spectroscopic analysis indicates the presence of volatile compounds, albeit in atypical proportions. Some observers highlight the limited release of dust and a non-gravitational acceleration that is difficult to explain solely by the effect of sublimated gas.

NASA and ESA have been cautious. They point out that 3I/ATLAS's rarity is due more to our lack of experience with interstellar comets than to properties impossible to reconcile with known physics. However, the scientific debate is ongoing.

The concern persists, as 3I/ATLAS's tail points toward the Sun, contrary to expectations based on the effect of the solar wind on icy comets. This singularity could be the clearest indication of an origin forged under conditions very different from those of our Solar System.

The detection of this cosmic wanderer was made possible by the Rubin Observatory in Atacama, equipped with the largest digital camera ever built for astronomy: 3.2 gigapixels that precisely scan the outer reaches of the solar system.

The Rubin telescope could discover more interstellar bodies like 3I/ATLAS, but its frequency remains a mystery: it has only made three detections in its history, and the available data are insufficient.

During the first week of September, several Martian probes, including the Mars Reconnaissance Orbiter and the European missions Mars Express and ExoMars, will monitor the comet's close passage to gather more information.

In 1977, the Big Ear radio telescope in Ohio captured the famous "Wow!" signal, a radio emission that lasted 72 seconds and was never repeated. Decades later, some researchers linked it to comet 3I/ATLAS, suggesting it could be a probe linked to that enigma that still baffles science.

It's true that the parallel is tempting: an interstellar object exhibiting unusual behavior and a wave in the same celestial region—a scenario worthy of the best science fiction. But science demands caution.

So far, no radio emissions or signs of technology have been recorded from 3I/ATLAS. Radio telescopes from the SETI project have observed it closely, but without obtaining conclusive evidence.

Could an advanced civilization send probes disguised as comets? The idea is not new. Carl Sagan himself speculated about the possibility of "ambush devices" in natural trajectories, believing it would be an effective method for exploring without arousing suspicion.

At the moment, there is only fragmentary data. Each interstellar object functions as a moving laboratory, a capsule that preserves the chemistry of other planetary systems and whose observation reveals clues about the formation and evolution of distant worlds.

These discoveries evoke a leap forward in time to the 17th century, the era in which Galileo turned his telescope toward the stars and changed our view of the cosmos. Today, new windows open onto previously inaccessible regions, revealing phenomena that defy known categories and demand new insights.

If an object like 3I/ATLAS were to emit an unequivocal signal, humanity would face a radical challenge: to accept the possibility of not being alone and to confront the cultural, scientific, and philosophical consequences of such a discovery.

For now, 3I/ATLAS continues its silent transit and in a few months will disappear into the darkness of the void, perhaps forever. The record of its journey will remain, one that prompted us to look beyond the obvious, between scientific certainty and cosmic conjecture.

Comet 3I/ATLAS is, so far, a fragment of interstellar matter, but it also reflects the most ambitious questions: it shows the chemistry of other stars and suggests, albeit remotely, the possibility of a hidden message.