3I/ATLAS Spits Deadly Gas as Avi Loeb and SPHEREx Record Bizarre Post-Perihelion Object Transformation

The interstellar visitor known as 3I/ATLAS did not simply survive its close brush with the Sun; it emerged fundamentally changed. Astronomers knew to expect some activity, but the object has started spewing a toxic mix of chemicals that makes it look less like a standard comet and more like a volatile celestial factory.

Data from high-tech observatories confirms that the intense heat from its close encounter with the sun triggered a chaotic change. This shift didn't just alter the object's physical state; it also released massive clouds of deadly gas.

Pear-Shaped Anomaly with Deadly Emissions

The SPHEREx space observatory has sent back new scans that give a clear view of just how much this object has changed. The observatory captured infrared images spanning wavelengths from 0.75 to 5.0 microns between 8 December and 15 December 2025. These are not just small snapshots.

Each image covers a massive area of roughly 300,000 kilometres on each side, which is about the same distance as the space between Earth and the Moon. On this massive scale, the data revealed a distinct pear-shaped distribution of dust and organic material, complete with an 'anti-tail' stretching towards the Sun.

This strange geometry stands in stark contrast to the gas plumes identified by the team, which appeared nearly round. Among the chemical signatures detected were cyanide at 0.93 microns and carbon monoxide at 4.7–4.8 microns, creating a hazardous envelope around the nucleus.

The observatory also picked up clear signals of water, organics, and carbon dioxide. The carbon dioxide plume, in particular, was massive, extending hundreds of thousands of kilometres outward. According to the analysis, the dust spectrum observed is a complex mix of scattered sunlight and thermal emission, painting a picture of a highly active and disrupting body.

Vanishing Ice and the Sudden Surge of Toxic Cyanide

When comparing this new data to observations taken before the object's closest approach to the Sun, the differences are striking. In August 2025, water-ice absorption features were prominent, but those have since vanished. According to a January 16, 2026, post on Medium by Harvard professor Avi Loeb, the spectrum is now dominated by organo-silicaceous dust grains rather than ice.

Simultaneously, the production of water gas has skyrocketed, increasing by a factor of roughly 20 compared to pre-perihelion levels. It appears that as the water emission surged, it brought other materials with it. Spectral features for cyanide and organics, which were previously unseen, suddenly appeared after the solar encounter.

The data also highlighted a curious absence of submicron dust particles. This lack of fine dust is consistent with the object's behaviour, specifically the absence of a cometary tail driven by radiation pressure. The object is shedding mass, but not in the way a typical comet usually does.

Material Ejected in Symmetric Plumes

The rate at which 3I/ATLAS is losing mass offers further insight into its violent unravelling. A new paper led by Carey Lisse reports that the object is losing water at a rate of approximately 180 kilogrammes per second. This rate is roughly equivalent to the mass loss of carbon dioxide and stands at about two-thirds of the carbon monoxide loss rate.

Brightness maps suggest that these emissions have distinct origins. The cyanide and organic materials appear to originate from the dust itself. In contrast, the water, carbon dioxide, and carbon monoxide gases seem to rise from a symmetric region centred on the nucleus. This symmetry in gas release, paired with the massive extension of the carbon dioxide plume, suggests a deep-seated internal process driving the exhaust.

Wobbling Jet System

To complement the infrared data, the Hubble Space Telescope captured a series of images on 14 January 2026 that exposed the structural chaos of the object. These images unveiled a glowing halo extending more than 130,000 kilometres towards the Sun. Inside this structure, processed images highlighted a sunward-directed anti-tail flanked by three evenly spaced mini-jets.

Further analysis of Hubble data suggests the object is not just venting; it is shaking. Research co-authored by Avi Loeb and Toni Scarmato indicates that the orientation of this jet system wobbles with a 7.1-hour period. These findings, combined with the new paper, document a configuration that defies standard cometary models in both composition and geometry.