The interstellar comet 3I/ATLAS carries an unprecedented level of deuterium-rich water, suggesting it formed in a much colder environment than our solar system. Discovered in July 2025, this comet is only the third interstellar object identified passing through our solar system.
The water in 3I/ATLAS contains roughly 30 to 40 times more deuterium than the water in Earth’s oceans. This high concentration indicates that the conditions leading to its formation differ significantly from those of our solar system’s comets.
Key statistics:
- The deuterium-to-hydrogen ratio in 3I/ATLAS is at least 30 times higher than in any comet measured in our solar system.
- The estimated age of 3I/ATLAS ranges between 3 billion and 11 billion years.
- The ALMA telescope, with its 66 radio antennas, detected the spectral fingerprint distinguishing deuterated water from ordinary water.
- During observations, the comet was located 1.37 astronomical units from the Sun.
Luis Salazar Manzano from the University of Michigan remarked, “Our new observations show that the conditions that led to the formation of our solar system are much different from how planetary systems evolved in different parts of our galaxy.” This discovery highlights a divergence in chemical history across planetary systems.
Teresa Paneque-Carreño emphasized that this finding is proof that conditions leading to the creation of our solar system are not ubiquitous throughout space. The amount of deuterium relative to ordinary hydrogen in 3I/ATLAS is higher than anything seen before in other planetary systems and comets.
The study detailing these findings was published in Nature Astronomy. As research continues, scientists aim to uncover more about the chemical history of interstellar objects and their implications for understanding galactic history.
