Interstellar Comet 3I/ATLAS Confirmed as Third Interstellar Visitor to Our Solar System

An interstellar comet, officially designated 3I/ATLAS, has been confirmed as the third known object from outside our solar system to pass through our celestial neighborhood. The celestial visitor, initially detected by the Asteroid Terrestrial-impact Last Alert System (ATLAS), has captured the attention of astronomers globally due to its unique characteristics and potential to offer unprecedented insights into other star systems.

Discovered on July 1, 2025, by the ATLAS system, the comet follows an unbound, hyperbolic trajectory past the Sun, indicating its origin beyond our solar system. "3I/ATLAS will not come closer than 1.8 AU (270 million km; 170 million mi) from Earth, so it poses no threat," according to scientific observations. Its closest approach to the Sun is anticipated around October 30, 2025, at a distance of approximately 1.4 AU, just inside Mars' orbit.

Observations by David Jewitt and Jane Luu using the Nordic Optical Telescope on July 2, 2025, confirmed that 3I/ATLAS was "clearly active" with a diffuse appearance. Further studies have highlighted its unusual composition, with its coma being overwhelmingly CO₂-dominated and exhibiting almost no water, a volatile ratio rarely seen in comets. This anomaly suggests it could be an "aeon-old fridge" releasing its contents, offering a glimpse into the early conditions of another star system.

Scientists are particularly interested in 3I/ATLAS because it represents a rare opportunity to study extraterrestrial material directly. The comet is believed to have originated from either the Milky Way's thin or thick disk, potentially making it billions of years old. Its study could provide crucial data on the formation and evolution of planetary systems beyond our own, with researchers exploring possibilities for spacecraft to visit the object for an on-location view.