3I/Atlas Shrinks? A Bizarre Development Leaves Experts Puzzled As Interstellar Object 'Disintegrates' After Brushing Past The Sun

Astronomers are baffled after the interstellar object 3I/ATLAS, the third of its kind ever detected, appeared to shrink and partially disintegrate following its close pass by the Sun. The object, which swept through the inner Solar System in late October, has defied expectations by displaying no typical cometary tail and losing visible mass after perihelion.

Experts say the strange evolution of 3I/ATLAS is unlike anything previously observed in space, prompting renewed debate about its origin and structure.

Discovery and Background

3I/ATLAS, officially designated C/2025 N1 (ATLAS), was discovered on 1 July 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Chile. It joins ʻOumuamua (2017) and 2I/Borisov (2019) as one of the few confirmed interstellar visitors to our Solar System.

Astronomers identified its trajectory as hyperbolic, meaning it is not gravitationally bound to the Sun and will eventually leave the Solar System for interstellar space. Its perihelion — or closest approach to the Sun — occurred on 29 October 2025 at approximately 1.36 astronomical units (AU). The object is expected to make its closest approach to Earth on 19 December 2025, at around 1.8 AU, posing no threat to the planet.

A Strange Encounter with the Sun

Following its solar encounter, telescopes detected a 13% reduction in 3I/ATLAS's visible size, sparking widespread astonishment in the astronomy community. Most comets heat up and emit bright tails as they approach the Sun, but 3I/ATLAS behaved differently. Instead of a trailing dust plume, it retained a compact, glowing form — even showing signs of a sun-facing jet rather than the usual anti-solar stream.

Researchers say the object's apparent shrinkage and lack of a visible debris trail could point to surface collapse, volatile loss, or internal fragmentation. Some specialists described the phenomenon as 'beyond standard cometary models,' highlighting the challenge of explaining its behaviour using existing theories.

Unusual Composition Revealed

Data from the James Webb Space Telescope (JWST) have deepened the mystery surrounding 3I/ATLAS. Infrared spectroscopy revealed a CO₂-dominated coma with measurable traces of H₂O, CO, OCS, water ice, and dust, and enhanced sunward outgassing. The CO₂/H₂O ratio was among the highest ever recorded for a comet, over four standard deviations above typical Solar System trends, suggesting that 3I/ATLAS may have formed near the CO₂ ice line or in a region exposed to strong cosmic radiation.

Scientists also observed a colour shift from reddish to bluish tones and a deep negative polarisation branch, implying a surface rich in mixed ices and dark material. Together, these traits point to a body that originated in an extremely cold, volatile-preserving environment beyond the Sun's influence.

Jet Anomalies and Competing Theories

Adding to the intrigue, observations revealed at least seven active jets emanating from the object's surface, some pointing directly toward the Sun. These jets appear to cause non-gravitational accelerations, slightly altering their path as they exit the inner Solar System.

Astrophysicist Avi Loeb suggested that the symmetrical pattern of these jets could resemble a 'thruster-like system,' leading to speculation about potential artificial origins. However, mainstream astronomers emphasise natural explanations, attributing the behaviour to uneven outgassing of volatile compounds as sunlight warms the surface. The scientific consensus remains that 3I/ATLAS is a natural interstellar comet, albeit one exhibiting highly anomalous characteristics.

Current Tracking and Ongoing Research

The object is now moving away from the Sun on a hyperbolic escape trajectory, gradually dimming as it travels beyond the orbit of Mars. Astronomers from NASA, the European Space Agency (ESA), and independent observatories continue to monitor for further changes in brightness and structure. While some fragmentation is possible, no complete disintegration has yet been confirmed.

For now, 3I/ATLAS stands as one of the most enigmatic interstellar visitors ever recorded, its behaviour challenging scientists' understanding of how objects from beyond our Solar System evolve when exposed to the Sun's intense radiation.