Astronomers first spotted the comet in mid-2025. “We first had images of it in June, but we didn’t know that it was something interesting to look at until July,” says Jason Steffen, an assistant professor of physics and astronomy at the University of Nevada, Las Vegas. “There are a number of astronomical surveys dedicated in full or in part to finding comets.” The one that first spotted 3I/ATLAS was the Asteroid Terrestrial-impact Last Alert System (ATLAS), developed by the University of Hawaii and funded by NASA, for which the comet is named.
Dr. Qicheng Zhang, a postdoctoral fellow at Lowell Observatory in Arizona, adds that while dozens of new comets appear annually, this one stands apart. “There are 30 major comets observable from the ground that have been discovered so far in 2025, so almost one a week,” he says. “However, interstellar comets like 3I/ATLAS are exceedingly rare.”
That said, scientists are hopeful to study more as technology advances. “We’ve only really been capable of discovering objects like this for the last 10 to 15 years, and this is the third one,” says Steffen. “So, I suspect going forward that we might see a new interstellar comet every two to five years.”
