Europa Clipper and Juice make simultaneous UV light observations of interstellar comet 3I/Atlas

Overview of November 2025 observations.
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By viewing interstellar comet 3I/Atlas when it was between the Jupiter probes Europa Clipper and Juice (on their way to Jupiter) in November 2025, the science teams for both were able to get a 360 degree view of the comet in ultraviolet wavelengths.
“As the comet passed between Juice and Europa Clipper, we were able to informally coordinate observations between the two spacecraft,” said Dr. Kurt Retherford, the principal investigator of Juice-UVS and Europa-UVS. “Crucially, we observed hydrogen, oxygen and carbon emissions. These elements are produced when gases escaping the comet’s nucleus break apart into atoms when exposed to sunlight.”
…“Observing the interstellar comet was some exciting bonus science. The resulting rare and unique dataset includes gas emissions and scattered dust,” said SwRI’s Dr. Philippa Molyneux, co-deputy principal investigator for the Juice-UVS instrument. “This was the first time we’ve had simultaneous direct views of a comet’s coma of escaping gas from two directions. Europa Clipper showed us the night side of the comet, with a great deal of scattered dust, while Juice imaged mostly glowing gas on the day side.”
…The researchers found higher levels of carbon emissions from 3I/ATLAS than expected early on, especially in comparison to typical comets from our solar system, corroborating similar findings through other observations about the interstellar comet’s origin and composition. Observing the trends of emissions over several days revealed how the ratios of these molecules changed and how the comet evolved during its journey through our solar system.
These results confirm once again that while Comet 3I/Atlas is from outside our solar system and has some unique features, it is still remarkably similar to ordinary comets found within our solar system.





