Study Dates Interstellar Comet 3I/ATLAS to 12 Billion Years, Oldest Yet Seen in Solar System
Updated
Updated · Smithsonian Magazine · Jun 26
Study Dates Interstellar Comet 3I/ATLAS to 12 Billion Years, Oldest Yet Seen in Solar System
3 articles · Updated · Smithsonian Magazine · Jun 26
Summary
Nature-published research estimates 3I/ATLAS formed 10 billion to 12 billion years ago, potentially making the interstellar visitor the oldest object ever observed in the solar system.
James Webb and Chile’s ALMA telescopes measured gases the comet released near the sun, using the ratio of two carbon forms to infer an origin just a few billion years after the Big Bang.
The data also found about 30 times more deuterium than in solar-system comets, pointing to formation in an extremely cold environment at or below minus 405 degrees Fahrenheit.
Discovered in July 2025 traveling about 137,000 mph, 3I/ATLAS is only the third known interstellar object and stands out as the biggest and brightest yet detected.
Scientists say such measurements offer a rare chemical snapshot of material from another planetary system, helping test how common life-friendly ingredients may be across the universe.
How many more ancient relics from the universe's dawn are currently passing through our solar system undetected?
What kind of alien solar system, born near the Big Bang, could have created and then ejected this icy visitor?
Does this comet's unique chemical cocktail hint at a different recipe for creating life-bearing planets across the universe?
3I/ATLAS: What the Third Interstellar Comet Reveals About the Origins of Planetary Systems
Overview
The interstellar comet 3I/ATLAS, discovered as it traveled through our solar system, quickly became a focus for scientists eager to study an object from beyond our Sun. In December 2025, a team led by Cordiner used the James Webb Space Telescope and ALMA in Chile to observe 3I/ATLAS, gaining an unprecedented view of this rare visitor. Their observations revealed that the comet was actively releasing material as it neared the Sun, offering valuable clues about its composition and the conditions it experienced in its original stellar system. These findings help expand our understanding of interstellar objects and planetary formation.