New images captured by Telescópio Espacial Hubble revealed enigmatic behavior in the interstellar comet 3I/ATLAS, which displayed jets of material pointing directly at Sol. The observations, carried out in January 2026 during a rare geometric alignment, show luminous structures that challenge the traditional understanding of cometary dynamics, generating intense debate in the scientific community about the object’s composition and internal mechanisms.
3I/ATLAS is only the third celestial body with a confirmed origin outside our Sistema Solar to be detected, making each piece of data collected extremely valuable. The oppositional alignment, occurring as the comet moved away from its closest approach to Sol in October 2025, provided prime viewing for Terra, allowing Hubble’s instruments to record unprecedented details of its solar radiation-driven activity.
The main anomaly lies in the direction of these jets. Normalmente, the tail of a comet is pushed by radiation and the solar wind, extending in the opposite direction from the star. However, 3I/ATLAS showed symmetrical beams and a prominent “anti-tail” that extended toward the heat source, suggesting complex processes of rotation and release of gases from its surface.
Detailed Solar Alignment Observations
The most revealing captures occurred on January 14 and 22, 2026, when the comet was positioned at a minimum phase angle of just 0.69 degrees relative to Terra and Sol. Essa unique geometric configuration favored a phenomenon known as opposition flare, where sunlight backscattered by dust ejected by the comet drastically increases its brightness, highlighting structures that would otherwise be invisible. The raw images already showed an extensive halo and a marked elongation in the solar direction, but digital processing revealed the true nature of the activity.
To isolate these features, astronomers applied advanced computational filters, such as the Larson-Sekanina technique, which removes the radial symmetry of the bright coma to highlight linear beams. The result was the clear identification of multiple distinct jets, separated by angles of approximately 120 degrees, a pattern that remained consistent across multiple exposures. Analysis of the temporal variation of these jets allowed scientists to estimate a rotation period for the comet’s nucleus of about 7.1 hours, indicating that the release of volatile material occurs at specific points on its surface as it rotates.
The chemical composition of the interstellar visitor
Spectroscopic analyzes carried out by ground- and space-based observatories have provided crucial clues about what fuels this unusual activity. The data reveal that the 3I/ATLAS coma is rich in carbon dioxide (CO2), which sublimates at lower temperatures and at greater distances from the Sol than water. Vapor of water and carbon monoxide were also detected, but in significantly smaller quantities, confirming a composition rich in distinct volatiles.
Complementary observations conducted by Telescópio Espacial James Webb added another layer of complexity by identifying traces of carbonyl sulfide, a compound rarely seen in comets from our own Sistema Solar. The sublimation of these different types of ice at varying rates as specific areas of the comet’s surface are exposed to sunlight during its rotation is the most likely explanation for the formation of the observed jets.
This gas release process is also responsible for the comet’s non-gravitational acceleration, a slight deviation in its trajectory that cannot be explained solely by the attraction of Sol and the planets. The thrust generated by the gas jets acts like small engines, subtly altering their course through space and providing further proof of their highly active nature.
A trajectory coming from outside the solar system
The path of 3I/ATLAS through our system is definitive proof of its exotic origin. The comet follows a sharp hyperbolic orbit, with a calculated eccentricity greater than 6, a value that confirms that it is not gravitationally bound to our Sol and is just passing through. Descoberto in July 2025 by the ATLAS survey system on Chile, its entry velocity, approximately 60 km/s relative to Sol, suggests an origin in the thick disk of Via Láctea, a region of older stars, which could imply an age of more than 7 billion years for the comet itself. Sua journey took him to the closest point to Sol, perihelion, in October 2025, at a distance of 1.36 Unidades Astronômicas (AU). In December of the same year, it made its closest approach to Terra, reaching a safe 1.8 AU, without posing any risk. Após the January alignment, the object continues its outward journey, and will no longer return to our solar system, heading into the depths of interstellar space.
Scientific debate about anomalous structures
The nature of the structures targeting Sol has provoked vigorous debate among experts. A group of researchers argue that the collimated jets and the anti-tail can be explained by a combination of rotation effects and asymmetric sublimation of an irregularly shaped nucleus, a behavior that, although rare, has already been observed in some comets from our Sistema Solar.
However, other astronomers argue that the remarkable symmetry and persistence of these jets, even at great distances from Sol, represent a distinct phenomenon. Para this group, the characteristics of 3I/ATLAS may indicate an internal composition or mass distribution that differs fundamentally from that of comets that formed in our cosmic neighborhood, requiring additional theoretical models for a full explanation.
Visual characteristics of the coma and anti-tail
After reaching perihelion, the 3I/ATLAS coma developed a distinct teardrop shape, a vast atmosphere of gas and dust that extends millions of kilometers into space. It is within this diffuse structure that the finest details were observed.
Specific image processing has managed to reveal the presence of double or even triple jets emanating from a central nucleus that remains too small to be resolved directly. The oscillation of these structures over time is aligned with the rotational period calculated for the object.
The so-called anti-tail, which is actually a projection of larger dust particles less affected by solar radiation pressure, has become exceptionally prominent. At its peak, this structure visually measured more than ten times the apparent diameter of the comet’s central region.
A faint greenish tone, detected by large-aperture telescopes, indicates the presence of diatomic carbon (C2) and cyanogen (CN) in the gas coma. With a current magnitude of around 16.7, the comet is a faint target, visible only with professional equipment and long-exposure cameras.
The role of technology in discovery
The ability to record such subtle details in a distant, faint object is a testament to the power of the Telescópio Espacial Hubble. Suas high-resolution cameras and the use of specific filters, which isolate particular wavelengths, were essential to enhance the contrast between the jets and the surrounding coma.
The success of the observation campaign also depended on close coordination with other observatories around the world. Telescópios as well as Gemini North, in Havaí, contributed spectrographic data that helped determine the comet’s gaseous composition and hue, complementing the high-definition images of Hubble.
Continuous object monitoring
Comet 3I/ATLAS will remain accessible for observation by large telescopes until mid-2026, although its brightness will continue to progressively decrease as it moves away from Sol. Agências space and research institutions will continue to monitor its variations in activity, collecting as much information as possible before it disappears into interstellar space. Cada new data contributes to a better understanding of the formation and diversity of primitive bodies in other stellar systems.
