Bold claim: Interstellar visitor or not, Comet 3I/ATLAS is turning heads as ESA’s Juice mission sniffs out its secrets in real time. In November 2025, the Jupiter Icy Moons Explorer (Juice) used five of its science instruments to study 3I/ATLAS, gathering data on the comet’s behavior and composition. Amid the science runs, Juice also images the comet with its Navigation Camera (NavCam). While NavCam isn’t a high-resolution science instrument—its primary job is to help Juice maneuver around Jupiter’s icy moons after a 2031 arrival—the team decided to squeeze a preview of data from a quarter of a single NavCam frame. What they saw exceeded expectations.
The NavCam image clearly shows the glowing coma surrounding the nucleus, along with hints of two distinct tails. The bright, plasma tail—a stream of electrically charged gas—stretches toward the upper part of the frame, while a fainter dust tail, comprised of tiny solid particles, appears to extend toward the lower left. For readers curious about cometary anatomy, this aligns with established models of coma and tail structure. More on comet architecture is available here.
The shot was captured on 2 November 2025, during Juice’s initial observing window for 3I/ATLAS, two days before the spacecraft’s closest approach at roughly 66 million kilometers away on 4 November. The full set of data from the five active instruments—JANUS (high-resolution optical), MAJIS (spectrometry), UVS (ultraviolet spectrometry), SWI (composition), and PEP (particle environment)—will arrive on Earth in mid to late February 2026. A delay is in play because Juice is temporarily using its main high-gain antenna as a heat shield against the Sun, leaving only its smaller medium-gain antenna to transmit data at a slower rate.
Although Juice was farther from 3I/ATLAS than the Mars orbiters were during their October observations of the comet, it captured data shortly after the Sun’s perihelion passage, a time when the comet’s activity tends to surge. That timing promises clearer signs of activity once all instrument data arrives. In particular, expect higher-resolution images from JANUS, plus spectrometry from MAJIS and UVS, composition details from SWI, and particle measurements from PEP.
For the latest updates and FAQs about comet 3I/ATLAS, consult esa.int/3IATLAS. To download an annotated version of the image, click here: esa.int/ESAMultimedia/Images/2025/12/Comet3IATLASshowsactivityinJuicenavigationcamerateaser2.
[Image description: A grainy space photograph showing a cluster of white points on a dark background. At the center lies a bright white blob with a faint line extending toward the top of the frame.]
