Records from the Juice mission detail the structure and tail of the interstellar comet 3I/Atlas visiting the solar system

This week, the global scientific community received an unprecedented set of data on the dynamics of objects that cross the boundaries of our planetary system. On February 19, 2026, Agência Espacial Europeia completed the complete reception of the telemetry and image packages sent by the Juice probe, which documented the passage of the interstellar comet 3I/Atlas. The material reveals morphological and chemical aspects that could not be observed by ground-based telescopes due to the object’s positioning in relation to Sol during its period of greatest activity.

The observations were carried out in a critical period, between November 5th and 25th, 2025, taking advantage of the probe’s cruise trajectory towards Júpiter. Neste interval, the spacecraft was in a privileged orbital position, free from visual interference that blocked observation from Terra. The comet, which reached its perihelion at the end of October last year, exhibited behaviors that now provide fundamental pieces for understanding the formation of distant star systems.

This celestial body is the third interstellar visitor confirmed by modern astronomy, following the historic passages of 1I/’Oumuamua and 2I/Borisov. Preliminary analysis of the processed images confirms that 3I/Atlas has hybrid characteristics, combining the intense activity of local comets with chemical signatures that denote its exotic origin. The mission, originally designed to study the icy moons of Júpiter, demonstrated operational versatility crucial to opportunity science.

Technical details of catches

The main instrument responsible for visual mapping was the scientific camera Janus, which operated in a programmed sequence to cover different aspects of the comet’s evolution. Durante the observation window, around 120 high-resolution images were obtained, using seven different spectral filters. Essa variation allowed researchers to isolate wavelengths between 380 and 1015 nanometers, making it easier to distinguish between dust, ionized gas and the object’s solid core.

The geometry of the encounter allowed the Juice probe to reach a minimum distance of approximately 66 million kilometers from the target. While Embora may appear distant on human scales, in astronomical terms this proximity was sufficient to resolve fine structural details within the comet’s coma and tail. The images show disconnections in the plasma tail and “knots” of material, suggesting rupture events or violent mass ejection driven by solar heat.

In addition to the optical images, the probe activated five other sensors from its instrumental suite to perform a complete scan of the environment around the comet:

– Espectrômetros visible and infrared imaging mapped the distribution of minerals and ices on the surface of the core.

– Sensores of particles measured the direct interaction between the comet’s tenuous atmosphere and the solar wind.

– Magnetômetros recorded disturbances in the local magnetic field caused by the ionization of sublimated gases.

Analysis of trajectory and origin

Discovered on July 1, 2025 by observatories located at Chile, 3I/Atlas quickly attracted attention due to its sharp hyperbolic orbit. Diferente of the periodic comets that orbit Sol in closed ellipses, this object traveled with speed and inclination that unequivocally indicated a provenance external to Sistema Solar. Sua passage through perihelion, the closest point to our star, occurred at a distance of 210 million kilometers, a safe margin that prevented its total disintegration, but sufficient to activate intense sublimation processes.

Viewing from Terra became unfeasible from October 2025 onwards, as the comet was visually positioned very close to the solar disk, being overshadowed by the star’s brightness. Foi in this scenario that the position of Juice proved to be strategic. Situada outside the orbital plane of Terra and on its way to the Jovian system, the probe had a clean and direct viewing angle, allowing continuous monitoring precisely in the phase where core heating was maximum and the release of volatiles reached its peak.

Navigation data confirms that the object is now on its way out of the system, returning to deep interstellar space. However, the legacy of his visit lies in the terabytes of data being decoded. Early interpretations suggest that 3I/Atlas may contain complex organic materials, preserved in the cold of deep space for eons, offering clues about prebiotic chemistry that may exist in other regions of the galaxy.

Dynamics and morphology observed

The images reveal a structural complexity that surprised experts. The comet had a bright and well-defined coma, as well as a system of double tails. One of them, composed mainly of plasma, extended in the opposite direction to Sol, guided by the lines of the interplanetary magnetic field. The second, formed by heavier dust, curved following the object’s orbital trajectory. Exposições lengths, up to 112 seconds, were needed to capture the faintest parts of these structures.

A particular phenomenon observed was the presence of radial jets emanating from specific regions of the nucleus. The most accepted hypothesis is that pockets of gas, trapped under the comet’s crust, expanded rapidly with heat, breaking the surface and creating geysers of material in space. Esse mechanism is similar to that observed in comets from our own system, which raises interesting questions about the universality of the formation processes of smaller bodies.

The photometry carried out indicates that the comet’s brightness increased by around 20% in the days following perihelion. Esse increase in luminosity was not uniform, presenting fluctuations that may be associated with the rotation of the nucleus. If the object rotates on its axis, different faces are exposed to solar radiation, periodically activating and deactivating gas jets, which would explain the variation in the density of the tail recorded in the image sequences.

Comparison with previous visitors

The 3I/Atlas study gains relevance when contrasted with its predecessors. 1I/’Oumuamua, detected in 2017, was an enigmatic object, with an extremely elongated shape and no visible cometary activity, behaving more like a rocky or metallic asteroid. Já 2I/Borisov, from 2019, was unmistakably a comet, rich in carbon monoxide and very similar to the bodies of Nuvem and Oort.

The new visitor appears to occupy an intermediate or entirely new spectrum of classification. Ele exhibits the classic activity of comets, like Borisov, but has peculiarities in its spectral composition that differentiate it. The presence of water and carbon dioxide has been confirmed, but the isotopic ratios are being investigated to determine the “signature” of the star where it formed. Juice’s ability to observe these nuances at multiple wavelengths is what makes this dataset so valuable.

The lack of catastrophic fragmentation, common in comets that come very close to Sol, suggests that the nucleus of 3I/Atlas has considerable structural integrity. Isso contrasts with models that predicted that objects formed in external regions of other systems would be loosely bound and fragile. The resilience of this celestial body implies compaction or lithification processes that have yet to be fully understood.

Legacy for space science

The successful capture of these images validates the concept of “opportunistic science” in long-duration missions. Interplanetary Sondas, although designed for specific targets, can act as mobile observatories, reacting to transient events that occur during their cruise years. The Juice mission control team demonstrated agility in reprogramming the instruments to track a target not originally planned, creating a protocol that could be used in future ESA and NASA missions.

The data collected will serve to refine computational models about the population of interstellar objects. Estima Thousands of these bodies are thought to pass through Sistema Solar annually, but most are too small or dark to be detected. The detailed study of a large and active specimen such as 3I/Atlas allows us to extrapolate statistics on the density of matter in the interstellar medium and the frequency of material exchange between stellar systems.

Furthermore, the information obtained boosts the planning of dedicated missions, such as Comet Interceptor. Esta future probe will be parked in space awaiting the discovery of a new target, and then intercepting it. Lessons learned from remote observation of Juice — such as the need for specific filters and adaptive exposure times — will be vital to the success of these future physical interception endeavors.

The astronomical community now awaits the publication of the peer-reviewed papers, which will detail the exact chemical composition and 3D modeling of the comet. Enquanto the 3I/Atlas plunges back into the darkness of space, taking with it the secrets of its parent star, the digital records left behind ensuring that its passage will continue to illuminate our knowledge of the cosmos for decades to come.