Third Interstellar Object, 3I/ATLAS, Confirmed Entering Solar System

Astronomers have officially confirmed the discovery of 3I/ATLAS, previously known as A11pI3Z, marking it as only the third interstellar object ever detected passing through our solar system. The European Space Agency (ESA) and the Minor Planet Center (MPC) verified its interstellar origin on July 2, 2025, following a period of intense observation by the global astronomical community.

Initial observations, including precovery data found by citizen scientist Sam Deen from the ATLAS survey dating back to June 25, revealed a highly hyperbolic trajectory. This extreme path, with an eccentricity estimated between 6 and 11.6, unequivocally indicates that 3I/ATLAS originated from beyond our solar system. "Astronomers may have just discovered the third interstellar object passing through the Solar System!" the ESA’s Operations account shared, highlighting the significance of the find.

The newly designated object, believed to be a comet due to tentative reports of cometary activity and a marginal tail, is estimated to be between 12 and 20 kilometers in diameter. Currently located just inside Jupiter's orbit, 3I/ATLAS is hurtling towards the Sun at speeds exceeding 60 kilometers per second. Its closest approach to the Sun is anticipated in October 2025, where it will pass within 0.4 AU of Mars, but poses no threat to Earth.

This rare visitor joins 'Oumuamua (2017) and 2I/Borisov (2019) as the only confirmed interstellar objects, offering scientists an unprecedented opportunity to study material from other star systems. Researchers are now racing to gather more data on its composition, shape, and rotation. The increasing frequency of such detections, aided by advanced sky surveys like the upcoming Vera C. Rubin Observatory, suggests that many more interstellar interlopers may be discovered in the future, providing invaluable insights into galactic processes.