The recent discovery of the interstellar object 3I/ATLAS, first identified on July 1, has captivated astronomers as it is believed to be older than our solar system by approximately three billion years. With this being only the third such object ever observed, the scientific community is deeply engaged in investigating its origins and age. According to a report presented at the Royal Astronomical Society’s National Astronomy Meeting 2025, 3I/ATLAS may have originated from the Milky Way’s thick disk, suggesting it could be a comet that is over seven billion years old, potentially the oldest comet known to date.
The analysis proposes that there’s a substantial two-thirds probability the object is a comet from the thick disk, an area of ancient stars. As researchers dive deeper into understanding its path, they rely on a new probability simulator designed to analyze interstellar objects. This system accounts for the trajectory and characteristics of around a billion stars identified by the Gaia satellite, allowing for predictions regarding the origins and physical properties of 3I/ATLAS. The model indicates that the object not only follows a typical interstellar velocity but also moves oscillating above and below the galactic plane, hinting at a long existence in the thick disk.
While the initial predictions are promising, astronomers like Chris Lintott from the University of Oxford emphasize the need for more empirical evidence to substantiate the claims surrounding 3I/ATLAS’s origins. Pamela Gay from the Planetary Science Institute notes that its journey could have involved multiple encounters with stars, thus complicating the understanding of its history. The object’s trajectory may have altered due to gravitational interactions with other celestial bodies, or it may have originated from a locality much closer to our solar system.
As 3I/ATLAS approaches the sun, it is expected to exhibit outgassing effects due to sunlight, which will allow astronomers to gather compositional data, particularly concerning its water content. Determining this aspect is crucial, as it is speculated that if it originates from the thick disk, it would possess a higher water abundance compared to rocky or dusty materials typically found in other comets. These compositional analyses will play a significant role in affirming the age and origin hypotheses associated with 3I/ATLAS.
The interplay of observational data and theoretical simulation will continue as scientists await further developments in the object’s behavior as it approaches the sun. Both Gay and Lintott point out that current understanding resembles a partially completed puzzle, with many pieces still needed to clarify the full story of 3I/ATLAS. As researchers gather more data, they hope to narrow down its history and ultimately confirm its status as a potential relic from an ancient era of the Milky Way.
In conclusion, the study of 3I/ATLAS not only enhances our comprehension of the solar system’s history but also underscores the significance of interstellar objects in unveiling cosmic narratives. While the excitement surrounding its discovery is palpable, it is also a reminder of the vast unknowns that remain in the field of astronomy. As scientists stand at the brink of uncovering new knowledge, the implications of 3I/ATLAS go beyond mere curiosity—it offers a glimpse into the deeper workings of our galaxy, potentially reshaping our understanding of celestial evolution and the origins of comets.
