Astronomers Confirm Discovery of 3I/Atlas: A Unique Interstellar Object

PARIS – Astronomers have officially confirmed the discovery of an interstellar object designated as 3I/Atlas, marking only the third instance of such a cosmic visitor detected within our solar system. The object, which scientists suspect may be either a comet or a cosmic snowball, was initially identified by a Chile-based observatory, part of the NASA-funded Atlas survey, on July 1, 2025. It is currently estimated to be between 10 km and 20 km in diameter, making it potentially the largest interstellar object observed to date.

According to Dr. Peter Veres, an astronomer with the International Astronomical Union’s Minor Planet Centre, which confirmed the object's status, “It looks kind of fuzzy. It seems that there is some gas around it, and I think one or two telescopes reported a very short tail.” This suggests that 3I/Atlas is actively outgassing, a characteristic typical of cometary bodies.

Dr. Richard Moissl, head of planetary defense at the European Space Agency, emphasized that while 3I/Atlas is approaching at a speed of over 60 km per second, it poses no threat to Earth. “It will fly deep through the solar system, passing just inside the orbit of Mars,” he explained. The trajectory indicates that the object is not bound by the Sun’s gravity, but rather is on a path originating from interstellar space, destined to exit the solar system in the coming years.

This discovery sheds light on the nature and frequency of interstellar objects. Dr. Jonathan McDowell, an astronomer at the Harvard-Smithsonian Centre for Astrophysics, noted, “We think that probably these little ice balls get formed associated with star systems, and then as another star passes by, it tugs on the ice ball, freeing it out. It goes rogue, wanders through the galaxy, and now this one is just passing us.” The object’s speed and size have led scientists to speculate that there may be as many as 10,000 interstellar objects drifting through our solar system at any given time, although most would be considerably smaller than 3I/Atlas.

The 3I/Atlas object is expected to reach its closest approach to the Sun, or perihelion, on October 29, 2025, at which point it will continue to brighten as it draws nearer. As it approaches perihelion, it will bend slightly under the influence of solar gravity before heading back into interstellar space. Dr. Mark Norris, an astronomer at the University of Central Lancashire, highlighted that the newly operational Vera C. Rubin Observatory in Chile could soon be discovering these interstellar visitors monthly, offering unprecedented opportunities for research.

While sending a mission to intercept 3I/Atlas is not currently feasible, scientists are hopeful that the study of such interstellar objects could provide vital insights into the conditions of other star systems. Dr. Moissl remarked that detecting precursors of life, such as amino acids, on these bodies could enhance our understanding of the potential for life beyond Earth.

The discovery of 3I/Atlas adds to the growing catalog of interstellar visitors, following the first observation of ‘Oumuamua in 2017 and the detection of 2I/Borisov in 2019. Despite earlier controversies regarding the origins of ‘Oumuamua, the scientific community remains focused on unraveling the mysteries surrounding these celestial wanderers. As technology advances, the prospect of finding and studying additional interstellar objects becomes increasingly plausible, potentially enriching our understanding of the universe.