The Jupiter Icy Moons Explorer (Juice) probe captured detailed images of the interstellar comet 3I/ATLAS in November 2025, revealing intense activity even after it passed through perihelion. The main photograph, taken by the JANUS camera on November 6, 2025, shows the object expelling jets of gas and dust from the face not illuminated by Sol, which challenges conventional models of cometary sublimation. Juice was approximately 66 million kilometers from the comet during observation, a distance equivalent to approximately 172 times that of Terra-Moon. The comet, discovered in July 2025, follows a trajectory that will take it close to Júpiter on March 16, 2026, 53.6 million kilometers from the planet.
The core of 3I/ATLAS is estimated to be 2.6 kilometers in diameter, larger than that of other known interstellar visitors, such as ‘Oumuamua and Borisov. The gaseous coma appears bright around the invisible nucleus, with a long trail of dust and filaments evident in the image. Setas in the photo indicate the direction of movement of the comet and the position of Sol, facilitating the analysis of the orientation of the jets.
Images reveal anomalous activity
The JANUS camera recorded more than 120 images during November 2025. The jets emerge from the dark side, contrary to the expectation that solar heating only activates the illuminated side. Observações complements of ground-based telescopes confirm this pattern since perihelion, which occurred on October 29 or 30, 2025.
Additional instruments on Juice collected spectroscopic data. The MAJIS and UVS spectrometers analyzed the composition of the ejected gases, while SWI and PEP examined neutral particles and molecules around the comet. Detailed results are currently being processed.
Multiple observations from scientific instruments
Five instruments operated simultaneously in November 2025 to study the object. The combination of optical images with spectral data makes it possible to determine the origin of the expelled materials. Juice used its high-gain antenna as a heat shield during transmission, which delayed the complete sending of data until February 2026.
ESA teams analyze the information to better understand the comet’s internal structure. Discussões over finds will occur in March 2026, coinciding with the closest approach to Júpiter.
Trajectory and future encounter with Júpiter
The interstellar comet follows a path that brings it closer to Júpiter on March 16, 2026, 0.358 AU from the planet. NASA’s Juno probe will observe the object on that date with instruments such as a low-frequency antenna. Juice will only arrive in the Jovian system in July 2031, but it took advantage of its current position to register the visitor.
The close pass to Júpiter may slightly alter the comet’s orbit, allowing additional studies of gravitational perturbations.
Capture details by JANUS camera
JANUS, designed to map the icy moons of Júpiter, was used to capture the comet in high multicolor resolution. The image highlights bright coma and tails of plasma and dust. The oval nucleus appears surrounded by a gaseous cloud, with visible ejections in filaments.
The distance of 66 million kilometers required careful processing to reveal fine details. The photo represents one of the best spatial records of the object to date.
Interstellar composition and origin
The comet exhibits behavior typical of objects from the Kuiper belt or Oort cloud, despite coming from outside Sistema Solar. Sua high speed at the time of discovery confirmed interstellar origin. Dados and Juice help to compare with local comets.
Persistent post-perihelion activity suggests internal reserves of volatiles. Análises future ones will clarify whether the object carries materials from another star system.
Analysis underway by ESA
Teams process data collected by multiple instruments. Combining JANUS observations with spectrometry reveals chemical composition. Preliminary Resultados indicate ejections consistent with sublimated ice, but with anomalies in orientation.
Discussions planned for March 2026 will integrate findings from Juice with observations from Juno. The comet continues to move away from Sol, gradually decreasing activity.
