3I/ATLAS Shock: Scientists Reveal Comet Is 'True Outsider' With Alien Chemistry

In a universe where history is usually measured in billions of years, a relic that may have existed before time as we know it has just come to visit us. An interstellar wanderer has streaked through our cosmic backyard for the third time in recorded history, giving us a brief, mysterious look at a star system that may no longer exist. This icy visitor, known as 3I/ATLAS, is now leaving in style, but not before leaving the scientific community both excited and very divided.

The ATLAS survey in Chile first saw the object on July 1, 2025. It was very fast, moving at 58 kilometers per second, which made it stand out right away. The comet's path was very hyperbolic, with an eccentricity of 6.139, which is the highest ever recorded for an interstellar object.

This means that it was moving too quickly for our sun's gravity to catch it. Most comets come from our own sun, but 3I/ATLAS is a true outsider. New information suggests that its family tree is older than anyone thought possible.

The 14-Billion-Year Mystery of 3I/ATLAS

The most startling revelation regarding 3I/ATLAS concerns its age. Associate Professor Michele Bannister of the University of Canterbury, working alongside Professor Chris Lintott at the University of Oxford, has spearheaded a study that places the comet's age between eight and 14 billion years.

Bannister's team suggested the object likely originated from the Milky Way's 'thick disk' — a region populated by the galaxy's oldest stars. To put that into perspective, if the higher estimate holds true, 3I/ATLAS was already an ancient, frozen veteran of the cosmos when our sun was nothing more than a swirling cloud of gas and dust.

'The chemistry of 3I/ATLAS is distinctive relative to our solar system comets,' Bannister explained, noting that the object's makeup acts as a chemical fingerprint of a distant, alien environment. Observations from the James Webb Space Telescope (JWST) have revealed a profile that is 'fizzing' with carbon dioxide — a stark contrast to the water-ice-heavy comets we usually see.

The JWST detected that carbon dioxide flux was incredibly high, alongside traces of carbon monoxide and carbonyl sulfide, though water-ice remained unusually scarce. Even more puzzling is the detection of atomic nickel and iron vapours within its coma.

These metals usually require extreme heat to vaporise, yet 3I/ATLAS was seen belching them out while still hundreds of millions of miles from the sun's warmth. Astronomers hypothesise these metals may be carried by volatile 'carbonyl' compounds that break apart under UV light.

Wobbling Jets and Radio Silence: The Search for 3I/ATLAS Technology

As 3I/ATLAS rounded the sun during its October perihelion on Oct. 29, 2025, reaching a maximum speed of 68 kilometres per second, astronomers at the Teide Observatory in Tenerife noticed something peculiar. Over 37 nights of intense monitoring using the Two-Meter Twin Telescope, they identified 'wobbling' jets within the comet's sun-facing anti-tail. These structures seemed to shift with a rhythmic, clock-like precision every seven hours and 45 minutes, suggesting a full rotation period of roughly 15.5 hours.

This strange, systematic behaviour reignited a controversial debate: could 3I/ATLAS be more than just a lump of primordial ice? Harvard astrophysicist Avi Loeb pointed to the object's specific geometry, including three evenly spaced inner jets, as a reason for intense scrutiny. The speculation grew loud enough that the Breakthrough Listen project pointed the 100-metre Green Bank Telescope toward the visitor on Dec. 18, just a day before its closest approach to Earth. The search targeted narrowband radio signals across a 1–12 GHz frequency range.

The results of the radio scan, however, were a definitive 'nondetection'. While initial sweeps picked up nearly 470,000 signals, every single 'ping' was eventually traced back to human technology or mundane radio interference. Specifically, the team ruled out any isotropic continuous-wave transmitters above 0.1 Watts — less power than a standard mobile phone. Lead researcher Ben Jacobson-Bell reported no credible signs of 'technosignatures', effectively silencing theories of alien origin for the time being.

Passing at a safe distance of 270 million kilometres on Dec. 19, 2025, 3I/ATLAS is now receding into the Leo constellation, destined to return to the interstellar void. It is projected to reach the inner Oort cloud by the year 2189. It leaves us with a pile of data and a profound reminder that while its physical behaviour may be familiar, its 14-billion-year-old soul remains a mystery we may never fully solve.