Astronomers have identified the interstellar object 3I/ATLAS, which may be older than the Sun itself. Detected on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert system (ATLAS) at the Observatory of Las Armas in Chile, 3I/ATLAS presents a unique challenge to conventional understanding of cometary characteristics. Unlike typical comets that are bound to our Solar System, 3I/ATLAS follows a hyperbolic orbit, suggesting it originated from outside our solar system and traversed the area around our Sun.
Research indicates that 3I/ATLAS could have formed in the Milky Way’s thick disk, a region of the galaxy populated by stars that emerged in its early history. A statistical model developed by astronomers at the University of Oxford estimates the age of 3I/ATLAS to be between 8 billion and 14 billion years, implying it predates the Solar System, which formed approximately 4.6 billion years ago. Further analysis by researchers at the University of Michigan also supports this theory, suggesting an age range of 3 billion to 11 billion years based on the object’s high galactic velocity.
A Celestial Time Capsule
This remarkable age positions 3I/ATLAS as potentially the oldest comet-like object ever discovered. The specifics regarding its original parent star remain elusive, as it has likely traversed the Milky Way for billions of years. The gravitational interactions with other stars during this time would have obscured its origin, effectively erasing its “stellar birth certificate.”
3I/ATLAS exhibits the defining features of a comet. It has a glowing coma—a cloud of gas and dust—created when its icy components heat up in proximity to the Sun, along with a tail pushed away by solar radiation. Observations reveal unusually high concentrations of carbon dioxide, water vapour, and various other volatile compounds across large areas of the object. Despite these characteristics, there is no credible evidence to suggest that 3I/ATLAS has artificial origins or propulsion systems.
While some theories have emerged, including speculation from astrophysicist Avi Loeb, the scientific community remains skeptical. Most experts assert that the available data aligns with established cometary physics, and the notion of 3I/ATLAS as an alien probe lacks substantial support.
Upcoming Closest Approaches
The flyby of 3I/ATLAS into the inner Solar System offers a rare opportunity for closer observation, with its nearest approach to the Sun projected to occur around October 30, 2025. It will come closest to Earth on December 19, 2025, when it will be approximately 1.8 astronomical units away, significantly closer than Mars. As 3I/ATLAS continues its trajectory out of the Solar System, it will become less visible, yet the data collected during its pass will provide invaluable insights.
Scientists are hopeful that the chemical and physical properties of this ancient object will aid in refining theories regarding planetary system formation and evolution. In a universe that spans billions of years and vast distances, 3I/ATLAS serves as a time capsule, preserving the history of star nurseries and systems that have long since dissipated. Its journey offers a glimpse into the grand narratives of existence within our universe, reminding us that even the smallest celestial bodies can hold significant stories of cosmic history.
