Interstellar object 3I/ATLAS may have originated from an ancient star system
Observations from the James Webb Space Telescope suggest the comet formed billions of years before the Sun.
Observations from the James Webb Space Telescope suggest that the interstellar visitor 3I/ATLAS may have formed in an ancient stellar nursery, according to The Economic Times. The object could have originated many billions of years before the Sun existed.
A paper in Nature Astronomy examined gases released by the comet in December 2025 while it was 2.5 AU from the Sun. Researchers found the methane in 3I/ATLAS has a deuterium-to-hydrogen ratio 13 times higher than comet 67P/Churyumov-Gerasimenko.
Scientists said this high ratio suggests the ice formed in an extremely cold area with high cosmic ray exposure and low metal content. The comet's low carbon-13 content also indicates an ancient origin from a period when the universe had fewer generations of stars.
A separate study by the Southwest Research Institute looked at water-ice grains using observations from August 2025 to April 2026. Lead author Dr. Silvia Protopapa said the grains are similar in size to those in local comets, but differ in how much dust is mixed into the ice.
The study noted that tiny grains of water ice mixed with dust could explain unusual infrared light patterns seen in the comet. Scientists are still investigating if changing solar heating or erosion caused the grain properties to change as the object moved away from the Sun.