Isotopic evidence for a cold and distant origin of 3I/ATLAS.

Isotopic analysis shows 3I/ATLAS formed over 12 billion years ago in a cold, metal-poor environment, with D/H ratios over ten times higher than known comets.

• Why it matters: Understanding the origins of interstellar objects like 3I/ATLAS offers crucial insights into the diversity of planetary system formation across the galaxy, filling gaps in knowledge about early star and planet formation conditions.
• What they did: Scientists measured isotopic ratios of water and carbon in 3I/ATLAS, finding deuterium enrichment and unusual carbon isotope ratios that suggest formation at temperatures around 30 K in a metal-poor environment, consistent with ancient galactic conditions.
• The result: These findings imply 3I/ATLAS is a relic from an early epoch of star formation, providing a rare glimpse into the composition and history of planetary systems formed billions of years ago.