Heavy hydrogen in comet 3I/ATLAS's methane indicates frigid origin

The interstellar comet 3I/ATLAS contains methane enriched with heavy hydrogen, providing chemical evidence of its formation environment. This signature suggests the comet's components formed in an extremely cold region, either in the planetary system of another star or in the precursor molecular cloud. This finding offers insights into the conditions of distant star systems before the comet entered our solar system.

Originally published by gnews