Interstellar Comet 3I/ATLAS Carries Unprecedented Heavy Water, Hinting at Cold Birth

Astronomers analyzing the interstellar comet 3I/ATLAS found an exceptionally high amount of heavy water (deuterium-rich water), suggesting it formed in a much colder, lower-radiation environment than our solar system. This marks the first successful water analysis of an interstellar object and points to diverse planetary-forming conditions across the galaxy, with future studies likely to reveal more such visitors as observational capabilities improve.