Interstellar comet 3I/ATLAS formed under alien conditions
The flight of 3I/ATLAS through the solar system last year was a stroke of luck for research. The water in the object was also analyzed.
(Image: Hans Anderson, Michigan News)
The interstellar comet 3I/ATLAS formed under conditions that differ significantly from those in the early solar system. This is according to an analysis of the water on the celestial body, reports the University of Michigan. According to the report, the ratio of the hydrogen isotope deuterium to regular hydrogen in the water on 3I/ATLAS is 30 times higher than on any comet in the solar system and even 40 times higher than in terrestrial water. This suggests that the comet's birthplace was significantly colder than the early solar system and that radiation there was also considerably lower, explains astronomer Teresa Paneque Carreño, who was involved in the work.
Not unexpected, but not yet proven
The research team led by Luis Salazar Manzano made this discovery using the MDM Observatory of the university and the Atacama Large Millimeter/Submillimeter Array (ALMA) of the European Southern Observatory in Chile. The latter is powerful enough to detect the differences between deuterium and hydrogen, the team explains. Such analyses are not new, but this is the first time they have been tested on an interstellar object. The result was proof that “whatever the conditions were that led to the creation of our solar system are not ubiquitous throughout space,” says Paneque Carreño: “That may sound obvious, but it’s one of those things that you need to prove.”
Videos by heise
The analysis was only possible because many things came together ideally, above all the early discovery of the celestial body. 3I/ATLAS was discovered in early July 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Chile, hence its name. The interstellar comet is only the third visitor to our solar system discovered during its passage. On its trajectory through the solar system, it was behind the sun from Earth's perspective in the autumn. Therefore, probes from different corners of the solar system had to step in temporarily to take over observation. Later, it could also be observed again from Earth. The analysis of its water is presented in Nature Astronomy.
(mho)
