Scientists Stunned: 3I/ATLAS Exhibits Bizarre Behaviour That Could Rewrite Space Science

The third confirmed interstellar object to enter the Solar System, 3I/ATLAS, has confounded the scientific community by exhibiting a series of physical and orbital characteristics that defy established cometary models.

From a nucleus estimated to be a million times more massive than 'Oumuamua to unexplained sunward jets, the data suggest the visitor may represent an entirely new class of celestial body.

Documented Anomalies Defy Expectation

Since its discovery on 1 July 2025, observations of 3I/ATLAS have steadily revealed behaviour inconsistent with any comet previously documented. Analysis indicates a hyperbolic trajectory and significant non-gravitational acceleration that standard outgassing models cannot explain easily.

One striking data point concerns its passage around Jupiter. Based on data from NASA's JPL Horizons, the predicted perijove (closest approach) during a 2026 encounter is 53.445 million kilometres, startlingly close to Jupiter's Hill radius of 53.502 million kilometres. That precise alignment seems facilitated by the observed non-gravitational acceleration near perihelion.

Further deepening the mystery: 3I/ATLAS's nucleus is estimated to be roughly a million times more massive than that of the first interstellar object, 1I/ʻOumuamua, and about one thousand times more massive than the second, 2I/Borisov, yet travels significantly faster.

Equally perplexing are observations of sunward jets or a so-called 'anti-tail,' confirmed via imaging from the HiRISE camera near Mars. Standard cometary physics dictates that solar wind pushes material away from the Sun; however, 3I/ATLAS displayed narrow jets streaming toward the star between July and November 2025.

The Polarisation Puzzle

Polarimetric observations add yet another layer of intrigue: 3I/ATLAS exhibits extreme negative polarisation, a pattern unseen in previously studied comets, interstellar or otherwise. In planetary science, negative polarisation at large phase angles typically indicates a surface structure composed of high-density materials, potentially metals, rather than the fluffy, porous aggregates found in local comets.

Finally, photometric data show the object's brightness varies periodically, with a 16.16-hour light cycle, originally thought to reveal its rotation period. But subsequent imaging by the Hubble Space Telescope on 21 July 2025 revealed that the majority of the observed light emanates not from a solid surface, but from a surrounding coma.

Scientific Debate Heats Up — And Implications Are Far-Reaching

The extraordinary nature of 3I/ATLAS has triggered intense debate. Some scientists urge caution, arguing that the data remain preliminary and that natural, but unusual, explanations may yet suffice. Others, including prominent voices in the astronomy community, suggest this object could force a revaluation of comet classification, formation models, and the diversity of small bodies in the galaxy.

The fact that 3I/ATLAS is the third confirmed interstellar object, after 1I/ʻOumuamua and 2I/Borisov, matters. Unlike ʻOumuamua, which showed no visible coma, and Borisov, which resembled Solar System comets, 3I/ATLAS forces astronomers to confront the possibility that interstellar visitors come in a far wider variety of compositions and behaviours than previously assumed.

If the metal-rich, CO₂-dominated, cryovolcanic model holds under further scrutiny, it could reshape understanding of how planetesimals form around other stars, and by extension, the prevalence and types of materials circulating in the galaxy. It might also yield clues about the chemistry of distant protoplanetary disks and the extent to which interstellar objects contribute to the seeding of organic and metallic materials across star systems.

Planetary Defence and Future Study

Beyond academic interest, the phenomenon has practical ramifications. NASA and international planetary defence networks are using 3I/ATLAS as a stress-test: parsing heterogeneous data, managing conflicting interpretations, and refining protocols for future interstellar visitors, all without the pressure of an impending impact threat.

Astronomers are now mobilising the observational arsenal. Further monitoring by JWST, Hubble, ground-based observatories, and planetary probes like HiRISE (when possible) could reveal whether the anomalies persist, or whether some might be explained by subtle observational biases or rare but natural processes.

Detailed spectroscopic analyses aim to track changes in outgassing, chemical composition, and coma morphology as 3I/ATLAS recedes from the Sun. If the metal-rich, CO₂-heavy composition persists, and cryovolcanic activity continues, it would substantially strengthen the case that 3I/ATLAS formed under conditions dramatically different from comets in our Solar System.

Should that prove true, the discovery would not only force a revision of comet taxonomy but reshape our understanding of how planetary building blocks form and evolve across the galaxy. It raises profound questions about the variety of small bodies circling distant stars, and what they might bring when they wander into a new system.