Hubble Spots Alien-Like Jets Erupting From 3I/ATLAS — And Scientists Are Stunned

Hubble has captured evidence of extraordinary jet activity from the interstellar comet 3I/ATLAS, which challenges established models of cometary physics and raises new questions about the nature of this rare visitor from beyond the Solar System.

Since its discovery on 1 July 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS), the object designated 3I/ATLAS has fascinated astronomers as only the third confirmed interstellar object ever observed. Its hyperbolic trajectory, high speed, and unexpected behaviour have made it an object of intense study and the subject of global scientific scrutiny.

Scientists initially expected 3I/ATLAS to behave like conventional comets: icy bodies from the distant reaches of space that emit gas and dust as they heat up during a close pass to the Sun. What Hubble and other instruments are showing now, however, is far more complex and in some cases unexpected.

Rare Interstellar Visitor Surpasses Expectations

Hubble’s observations of 3I/ATLAS were first made public on 7 August 2025. The NASA/ESA space telescope photographed the object on 21 July 2025 when it was approximately 365 million kilometres from Earth. These images revealed a teardrop–shaped cloud of dust and gas streaming from the object’s icy nucleus while also allowing astronomers to refine estimates of its size.

Analysis of the data suggests the nucleus could be as small as 320 metres or as large as 5.6 kilometres across, a wide range that reflects both the complexities of observing such distant objects and the limitations of current instrumentation.

Hubble detected a plume of material ejected from the sunward side of 3I/ATLAS, behaviour consistent with sublimation, the process by which ices turn directly into gas under solar heating. Typical cometary behaviour would also produce a tail streaming away from the Sun. That feature, observed in many comets, is present but appears faint and unusual in structure for 3I/ATLAS.

The object is moving at approximately 210,000 km/h, the highest velocity recorded for any visitor to the Solar System, indicating it has been drifting through interstellar space for billions of years before its encounter with our star.

Observations Reveal Unusual Activity

Even as 3I/ATLAS behaves in some respects like a comet, other aspects of its behaviour are confounding scientists. Observations from Hubble and other telescopes have shown ongoing activity that does not neatly fit within traditional models of cometary physics.

Images from NASA and the European Space Agency have captured significant jets of gas and dust erupting from the object as it warms on its path towards the Sun. This activity was expected as sublimation increases closer to perihelion, the point of closest approach to the Sun, but the scale and persistence of these jets are surprising to researchers.

These eruptions are not merely transient spikes of material. Hubble data show sustained jets that remain collimated and defined over extended periods, a phenomenon not anticipated in most comet models. Traditional comet jets become diffuse and disperse rapidly due to rotation and solar forces, but 3I/ATLAS’s jets have maintained coherence, prompting deeper analysis.

Astronomers using NASA’s James Webb Space Telescope (JWST) have also contributed crucial data. Infrared spectroscopy performed on 6 August 2025 revealed that the object’s coma, the nebulous envelope of gas and dust that surrounds the nucleus, is dominated by carbon dioxide (CO₂). This composition differs significantly from typical Solar System comets, for which water (H₂O) often dominates outgassing signatures.

The presence of such a CO₂-rich coma suggests 3I/ATLAS formed in a different environment, potentially exposed to higher radiation levels or in regions of its parent stellar system where CO₂ ice was abundant. These results align with spectroscopic analysis showing elevated CO₂ to H₂O ratios, among the highest ever recorded for a comet.

Scientific Debate Intensifies Over Origins

The unusual nature of 3I/ATLAS has sparked significant debate within the scientific community about how to interpret these observations. While there is broad consensus that it is a natural interstellar object, the mechanisms driving its sustained jet activity and distinctive composition remain areas of active research.

Some astrophysicists point to the high carbon dioxide content as evidence of formation in a part of another star’s planetary system that was very different from our own. Others caution that the jets, while extraordinary, may still be compatible with natural processes not yet fully understood by cometary science.

Hubble’s high-resolution imaging continues to be central to this research effort. By tracking changes in 3I/ATLAS’s appearance over time, astronomers can refine models of dust and gas emission and better understand how interstellar objects interact with the Sun’s radiation.

International collaborations combining data from Hubble, JWST, and ground-based observatories have become essential as well. Each platform contributes complementary data: Hubble’s ultraviolet and optical observations, JWST’s infrared spectroscopy, and terrestrial telescopes’ broader temporal coverage. This integrated approach is crucial for resolving outstanding questions about the dynamics of 3I/ATLAS.

As 3I/ATLAS continues its journey through the Solar System, astronomers will closely monitor further changes. Future observations planned in early 2026 aim to capture post-perihelion behaviour as the object moves away from the Sun and its activity declines. These data will help refine models of interstellar comet behaviour and their role in seeding information about environments beyond our stellar neighbourhood.

3I/ATLAS’s visit highlights the rare opportunity interstellar objects provide to astronomers: a direct glimpse into material that formed around other stars, carrying with it clues about processes far beyond our own cosmic backyard.