When the ATLAS survey telescope in Chile discovered interstellar comet 3I/ATLAS on July 1, 2025, it quickly attracted attention because it was not just the third known object outside the solar system. Some researchers, including Harvard astrophysicist Avi Loeb, believe that some of the unusual features are interesting enough to leave open the possibility of an artificial origin, fueling widespread speculation about alien technology. Most astronomers favor the natural explanation. Now, a new analysis by researchers at the University of Oxford suggests the object may be even more extraordinary. Their models suggest that 3I/ATLAS may be about 7 billion years old, meaning it may have formed billions of years before the Sun and may be older than our entire 4.6 billion-year-old solar system, making it possibly the oldest comet ever observed.
Why some people think interstellar comet 3I/ATLAS could be aliens
Shortly after 3I/ATLAS was discovered, Harvard astrophysicist Avi Loeb and his collaborators turned it into one of the most talked about objects in astronomy by asking whether it was more than just a comet. In their paper, they argue that the object’s unusually high speed, steep trajectory and other strange features deserve to be considered as potential signs of something far stranger. The paper’s most compelling argument is that 3I/ATLAS may be a “technological artifact” and, according to the “dark forest” interpretation of the Fermi Paradox, even “potentially hostile.”Loeb and his co-authors pointed out several details that they believe make the object unusually interesting. They say 3I/ATLAS is very close to Venus, Mars and Jupiter, and believe such a path could theoretically help technological objects observe planets while being difficult to detect from Earth. In the paper, they further propose that the object’s trajectory through the solar system, and the possibility of hidden propulsion-related maneuvers near perihelion, make it worthy of consideration as a possible interstellar probe, rather than treating it as a regular comet.The framework quickly captured the public’s imagination, as Loeb was already known for pushing unconventional explanations for interstellar visitors. In later writing, he said scientists should remain open to the possibility of a “Trojan horse” that looks like a rock on the surface but hides advanced technology inside, describing 3I/ATLAS as an opportunity to explore “exciting possibilities” rather than a firm conclusion. His argument was not that the alien explanation was proven, but rather that the anomalies were interesting enough to keep the idea alive.
Oxford University scientists estimate this comet may be older than the sun
The new analysis comes from Matthew Hopkins of the University of Oxford, who developed the Ōtautahi-Oxford model with Professor Chris Lintott and collaborators at the University of Canterbury in New Zealand. The model uses the trajectories of interstellar objects to estimate their origins and ages. When Hopkins ran the newly discovered 3I/ATLAS through a model, the results surprised even the researchers.According to the team’s findings, there is about a two-thirds chance that the comet is older than our solar system, which was 4.6 billion years ago. The most statistically accurate estimate of its age is about 7 billion years. “Our statistical methods indicate that 3I/ATLAS is likely the oldest comet we have ever seen,” Hopkins said in a statement released by the Royal Astronomical Society.
The object may have come from the Milky Way’s thick disk
One clue about the comet’s age lies in its unusual path through the solar system.Most stars, including the Sun, belong to the Milky Way’s thin disk. Above and below it is a thicker, older population of stars called a thick disk. These stars are believed to be about 10 to 12 billion years old.Because 3I/ATLAS entered the solar system at a steep angle, the Oxford team believes it likely originated in this ancient region of the Milky Way.Professor Chris Linto said the object “appears to have originated from the thick disk of the Milky Way”, providing astronomers with a rare opportunity to study material that formed around stars much older than the Sun.
Why 3I/ATLAS is scientifically important
Comets preserve ancient material from the protoplanetary disks from which they formed. If the age estimate is correct, 3I/ATLAS may contain clues about the conditions that existed billions of years before the formation of the solar system.Preliminary observations indicate that the comet is rich in water ice and volatile compounds. Scientists hope detailed spectroscopic studies will reveal more about the chemical composition of ancient star systems and how the Milky Way evolved over time.In this sense, 3I/ATLAS is not just another comet. It may represent one of the oldest pieces of planetary material ever observed.
Age estimates are still a probability, not a certainty
Astronomers stress that the 7 billion-year figure is not directly measured.No one can determine the age of comets the way geologists determine the age of rocks on Earth. Instead, the estimate comes from a statistical model based on the object’s orbit and possible galactic origin.This means that future observations and discoveries of other interstellar objects may refine or even challenge current estimates.Even so, the researchers believe 3I/ATLAS is likely to become an important benchmark for understanding objects from distant star systems.
More interstellar visitors could soon be discovered
Until 2017, no confirmed interstellar objects had been discovered. Since then, astronomers have identified ‘Oumuamua, 2I/Borisov and now 3I/ATLAS.The Vera C. Rubin Observatory has begun operations in Chile, and this number is expected to increase significantly. Scientists believe it discovers several interstellar visitors every year.Each new object will provide an opportunity to compare different regions of the Milky Way and further test the Oxford model.As for 3I/ATLAS, it has left the solar system and embarked on a one-way journey back to interstellar space. But the data collected during its brief visit will likely keep astronomers busy for many years to come.
