JUICE, Europa Clipper Capture 3I/ATLAS From 2 Sides, Revealing Interior Chemistry
Updated
Updated · Universe Today · May 22
JUICE, Europa Clipper Capture 3I/ATLAS From 2 Sides, Revealing Interior Chemistry
5 articles · Updated · Universe Today · May 22
December 2025 observations by ESA’s JUICE and NASA’s Europa Clipper produced the first simultaneous two-sided views of interstellar comet 3I/ATLAS, capturing ultraviolet emissions from opposite hemispheres after it re-emerged from behind the Sun.
SwRI-led UV spectrographs detected hydrogen, oxygen and carbon as sunlight broke apart gases escaping the nucleus, letting researchers probe the comet’s interior rather than just its outer layers.
Higher-than-expected carbon emissions—stronger than in many Solar System comets—confirmed earlier findings, while several days of tracking showed molecular ratios shifting as 3I/ATLAS moved through the Solar System.
Europa Clipper saw the comet’s dustier night side and JUICE its gas-bright day side, giving scientists a rare dataset to compare water ice and carbon dioxide ice and infer whether the object formed in a star system like ours.
What secrets did two spacecraft uncover by simultaneously viewing an interstellar comet’s day and night sides for the first time?
An alien comet has 30 times more heavy water. What does this strange chemistry reveal about its distant home star system?
Unveiling 3I/ATLAS: How a Water-Rich Interstellar Comet Redefined Our View of Planetary Systems
Overview
In late 2025, astronomers made a historic observation of 3I/ATLAS, an interstellar comet that entered our solar system near Jupiter’s orbit. Traveling at a remarkable speed of 58 kilometers per second, its unbound, hyperbolic path showed it came from far beyond the Sun’s Oort Cloud. Scientists estimate 3I/ATLAS spent at least 3 billion years journeying through the galaxy before reaching us. This rare event gave researchers an unprecedented look at a visitor from another star system, helping them learn more about the origins and diversity of comets beyond our solar neighborhood.