Astronomers Discover 3I/Atlas: Potentially the Oldest Known Comet

Astronomers have identified an intriguing interstellar object, 3I/Atlas, which may be the oldest known comet, potentially predating our solar system by three billion years. First detected on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Chile, 3I/Atlas is only the third object recorded to originate from beyond the solar system.

The announcement was made during a presentation at the UK’s Royal Astronomical Society meeting in Durham, where researchers from the University of Oxford shared their preliminary findings. Matthew Hopkins, an astronomer and co-author of the study, expressed enthusiasm for the discovery, stating, "We’re all very excited by 3I/Atlas. It could be more than seven billion years old and may be the most remarkable interstellar visitor yet."

The object was initially observed when it was approximately 670 million kilometers from the Sun. The research team hypothesizes that 3I/Atlas formed in the 'thick disk' of the Milky Way, a region populated by ancient stars. This origin suggests a composition rich in water ice, leading researchers to predict that as 3I/Atlas approaches the Sun later this year, it will generate a glowing tail due to vaporization processes.

Professor Chris Lintott, a co-author of the research, emphasized the significance of this object, noting, "This is an object from a part of the galaxy we’ve never seen up close before. We think there’s a two-thirds chance this comet is older than the solar system and that it’s been drifting through interstellar space ever since."

The implications of 3I/Atlas's age are substantial for our understanding of cometary formation and the history of our galaxy. Previously, only two other interstellar objects have been confirmed: 1I/'Oumuamua, discovered in 2017, and 2I/Borisov, identified in 2019. The rarity of these findings underscores the importance of ongoing astronomical research.

In anticipation of further studies, astronomers are preparing to utilize the Vera C. Rubin Observatory in Chile, which is expected to commence full operations later this year. This powerful telescope could potentially identify between five to fifty new interstellar objects, expanding our knowledge of cosmic bodies that traverse our solar system.

As 3I/Atlas becomes visible to amateur astronomers later this year, it may provide an unprecedented opportunity for both professional and citizen scientists to observe a celestial body that could reshape our understanding of the formation and evolution of comets in the universe. The continued exploration of interstellar objects is essential for unraveling the mysteries of the cosmos and the origins of our solar neighborhood.