During November 2025, ESA’s Jupiter Icy Moons Explorer (JUICE) used five of its science instruments to observe 3I/ATLAS. The instruments collected information about how the comet was behaving and what it was made of.
Additionally, Juice caught the comet with its onboard navigation camera (NavCam), which was designed not as a high-resolution science camera, but to help Juice navigate Jupiter’s icy moons after its arrival in 2031.
Although data from science instruments won’t arrive at Earth until February 2026, our Juice team couldn’t wait that long. They decided to download just a quarter of a single NavCam image to see what was available to them. The comet, which was extremely clearly visible and surrounded by signs of activity, surprised them.
Not only do we clearly see the glowing halo of gas around the comet, known as its coma, we also see a hint of two tails. The comet’s ‘plasma tail’ – made up of electrically charged gas, extends towards the top of the frame. We can also see a light ‘dust tail’ – made up of tiny solid particles – extending to the lower left of the frame. More information on the structure of comets.
The image was taken on 2 November 2025 during the first slot of JUICE for 3I/ATLAS observations. This was two days before Joos’s closest approach to the comet, which occurred on November 4 at a distance of about 66 million km.
We expect to receive data from five scientific instruments – Janus, Majis, UVS, SWI and PEP – operational during observations on 18 and 20 February 2026. The delay is because Juice is currently using its main high-gain antenna as a heat shield to protect it from the Sun, and leaving its smaller medium-gain antenna to send data back to Earth at a much lower rate.
Although Juice was further away from 3I/ATLAS in October than our Mars orbiters, it saw 3I/ATLAS just after the comet made its closest approach to the Sun, meaning it was in a more active state. We expect to see clear signs of this activity in data from science instruments. It includes not only images from JANUS – Jus’s high-resolution optical camera – but also spectrometry data from MAJIS and UVS, composition data from SWI, and particle data from PEP.
For the latest updates and FAQs related to Comet 3I/ATLAS, visit esa.int/3IATLAS.
Click here to download an annotated version of the image.
[Image description: Grainy space image, with white dots on a dark background. At the centre of the image is a larger, bright white blob with a faint white line stretching towards the top of the frame.]
