In a jaw-dropping cosmic surprise, NASA's Europa Clipper spacecraft – on its way to hunt for life on Jupiter's moon – just captured a never-before-seen ultraviolet glimpse of the mysterious interstellar comet 3I/ATLAS. This rare visitor from another star system revealed its glowing tails and chemical secrets from an impossible angle that left Earth- and Mars-based telescopes in the dark. What secrets from beyond our Solar System is this comet hiding?
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| This composite image of the interstellar comet 3I/ATLAS was captured on November 6, 2025 by the UVS instrument on board NASA’s Europa Clipper spacecraft from a distance of around 164 million km (103 million miles). Image credit: NASA / JPL-Caltech / SwRI. |
Latest update (December 2025): Fresh analyses from the Europa-UVS team confirm intense outgassing of water molecules breaking into hydrogen and oxygen – offering tantalizing clues about the comet's violent journey across the galaxy. Source: NASA Science (December 18, 2025)
A Historic Encounter in Deep Space
Scientists using the Ultraviolet Spectrograph (UVS) instrument aboard NASA’s Europa Clipper spacecraft have observed 3I/ATLAS – only the third confirmed interstellar object ever detected entering the Solar System from beyond. While most Mars- and Earth-based telescopes were poorly positioned to see the interstellar visitor due to its proximity to the Sun, Europa Clipper was able to collect data from a unique vantage point as the space probe traveled toward Jupiter.
Europa Clipper: The Unexpected Comet Hunter
Europa Clipper launched in 2024 and is scheduled to arrive in the Jovian system in 2030, where it will orbit Jupiter and perform 49 close flybys of its icy moon Europa. The UVS instrument collects ultraviolet light to assess the composition of Europa’s atmospheric gases and icy surface materials.
“We’re excited that this opportunity to view another target on the way to Jupiter was completely unexpected,” said Europa-UVS principal investigator Dr. Kurt Retherford, a researcher at the Southwest Research Institute. “Our observations have allowed for a unique and nuanced view of the comet.”
From Discovery to Deep Space Drama
3I/ATLAS was discovered by the NASA-funded ATLAS survey telescope in Rio Hurtado, Chile, on July 1, 2025. At the time, the interstellar comet was at a heliocentric distance of 4.51 astronomical units (AU), with an eccentricity of 6.13.
Within a week of the discovery, analysts at NASA’s Jet Propulsion Laboratory identified its trajectory through the Solar System. The Europa Clipper team quickly realized their spacecraft could observe 3I/ATLAS during November 2025 – bridging the critical gap when Earth was blinded by the Sun.
With the comet’s trajectory passing between Europa Clipper and the Sun, the vantage point enabled the UVS team to view the comet from a unique perspective – looking "from behind" at both the dust tail trailing behind and the plasma tail pointing away from the Sun.
“We’re hopeful that this new view, along with observations from Earth-based assets and other spacecraft, will help us to piece together a more complete understanding of the tails’ geometries,” said Europa-UVS co-deputy principal investigator Dr. Thomas Greathouse, also from the Southwest Research Institute.
Unveiling the Comet's Alien Chemistry
The UVS instrument detected oxygen, hydrogen and dust-related features, supporting strong evidence that 3I/ATLAS underwent intense outgassing right after its closest approach to the Sun.
“Europa-UVS is particularly adept at measuring fundamental transitions from atoms and molecules,” Dr. Retherford said. “We can see gases come off the comet, and water molecules break apart into hydrogen and oxygen atoms.”
This breakthrough capability provides a deeper view into the comet’s processes and composition. “Understanding the composition of the comet and how readily these gases are emitted can give us a clearer view of the comet’s origin and how it may have evolved during transit from elsewhere in the Galaxy to our Solar System,” said Europa-UVS co-deputy principal investigator Dr. Tracy Becker.
“What are the chemical processes at play, and how can we unravel the comet’s origin in its own Solar System? Were those processes similar to how we believe our Solar System formed? Those are big questions.”
Original source: Sci.News – Europa Clipper Captures Unique View of 3I/ATLAS
This interstellar encounter reminds us how vast and mysterious the universe truly is – and how even a mission designed for Jupiter's moon can uncover wonders from another star system!