Bold claim: a distant comet is revealing its secrets from a solar-tinged stage, and the world is catching glimpses of its true nature earlier than expected. That’s the gist of the November 2025 findings from ESA’s Jupiter Icy Moons Explorer (Juice), which used five of its science instruments to study 3I/ATLAS and learn how this interstellar visitor behaves and what it’s made of.
Juice also captured the comet with its Navigation Camera (NavCam). NavCam isn’t designed for high-end science imaging; its primary job is to help Juice navigate around Jupiter’s icy moons after the mission’s planned arrival in 2031. Even so, the team couldn’t resist testing the data pipeline early and downloaded a fraction of a single NavCam image to peek at the scientific payoff. The result surprised them: a clearly visible coma—the glowing halo of gas surrounding the comet—and hints of two tails. The plasma tail, composed of electrically charged gas, stretches toward the top of the frame, while a fainter dust tail—made of tiny solid particles—seems to trail toward the lower left. For context on comet structure, see ESA’s overview linked in the original release.
The image was taken on 2 November 2025, during Juice’s first observing window for 3I/ATLAS. It came just two days before Juice’s closest approach to the comet, on 4 November, at a distance of about 66 million kilometers.
Data from the five operated science instruments—JANUS, MAJIS, UVS, SWI, and PEP—are expected to arrive on Earth on 18–20 February 2026. The delay stems from Juice currently using its main high-gain antenna as a heat shield against the Sun, leaving the smaller medium-gain antenna to transmit data at a much lower rate.
Even though Juice stood farther from 3I/ATLAS than ESA’s Mars orbiters did during their October observations, it still caught the comet soon after perihelion, when it’s typically more active. The mission team anticipates clearer signs of activity in the instrument data, including JANUS’s high-resolution optical imagery, spectrometry from MAJIS and UVS, composition data from SWI, and particle measurements from PEP.
For the latest updates and FAQs about comet 3I/ATLAS, visit esa.int/3IATLAS. An annotated version of the image can be downloaded here: esa.int/ESAMultimedia/Images/2025/12/Comet3IATLASshowsactivityinJuicenavigationcamerateaser2.
[Image description: A grainy space photo with white dots against a dark background. At the center is a bright white blob with a faint white line extending toward the top of the frame.]
And this is where the conversation gets interesting: these initial glimpses from NavCam, combined with upcoming data from the instrument suite, could reshape how scientists interpret interstellar comets’ activity. Do you think these early signals will hold up as the full data set arrives, or might they change with more detailed measurements? Share your thoughts in the comments.
