CITIC research team retraces 10 million years of history of interstellar comet 3I/ATLAS

An international team based at CITIC, the research centre of the University of A Coruña and a member of the CIGUS Network — an initiative promoted by the Xunta de Galicia that brings together Galicia’s leading centres of scientific excellence — has reconstructed the orbital history of the third interstellar object ever detected in our Solar System: 3I/ATLAS.

The study, led by researcher Xabier Pérez Couto, is currently available in the open-access repository arXiv and has been submitted for publication in the journal The Astrophysical Journal. It reveals the path this comet has taken over the last 10 million years as it travelled through the Milky Way.

3I/ATLAS was discovered on 1 July by the ATLAS (Asteroid Terrestrial-impact Last Alert System) programme in Chile. It is only the third known interstellar object — a visitor from beyond our Solar System. While such bodies are thought to be relatively common, only two others have ever been observed: 1I/‘Oumuamua (2017) and 2I/Borisov (2019).

This discovery was made possible thanks to the highly precise data from the Gaia space mission, led by the European Space Agency (ESA). In Galicia, Gaia is coordinated by Minia Manteiga, also a researcher at CITIC. Using this data, the team calculated the orbits of 3I/ATLAS and over 13 million stars to identify any close encounters that may have occurred.

As Xabier Pérez Couto explains, “What makes 3I/ATLAS so special is that it allows us to study the evolution of objects from other star systems — something we had previously only been able to model in theory. Every observation opens a new window into the Universe’s past.”

Among the most remarkable features of this interstellar comet are its high level of cometary activity — a sign of its richness in ice — and its extreme speed of around 58 km/s (over 200,000 km/h). This makes it a brief visitor, but one of immense scientific value. According to the CITIC team’s findings, it is also extraordinarily ancient, with an estimated age of around 10 billion years. In essence, it is a true cosmic time capsule, preserving clues about the formation and evolution of the first planetary systems in the Universe.

The research also highlights just how challenging it is to trace the origins of individual interstellar objects. However, the team notes that as more of these objects are discovered, it will become possible to identify large-scale chemical and dynamical patterns across the galaxy — offering unique insights into how planets and comets form and spread throughout the Cosmos.