Interstellar Comet 3I/ATLAS Formed in Extremely Cold Environment, Study Reveals
Observations of comet 3I/ATLAS indicate it originated in a much colder region than our solar system, providing insights into diverse planetary formation conditions.
Recent observations using the Atacama Large Millimeter/submillimeter Array (ALMA) have provided new insights into the origins of interstellar comet 3I/ATLAS. Detected in July 2025, 3I/ATLAS is the third known interstellar object to traverse our solar system. ALMA's analysis revealed a significantly higher ratio of deuterated water (HDO) to ordinary water (H₂O) in the comet compared to solar system comets and Earth's oceans. This elevated ratio suggests that 3I/ATLAS formed in an environment with temperatures below 30 Kelvin (-243.15°C), much colder than the conditions present during the formation of our solar system.
Lead researcher Luis E. Salazar Manzano noted that the findings indicate that planetary systems can evolve under very different conditions in various parts of the galaxy.
The study, published in Nature Astronomy, underscores the diversity of planetary formation processes across the Milky Way and highlights the value of interstellar objects like 3I/ATLAS in understanding the history and evolution of other star systems.