Third-ever confirmed interstellar object spotted blasting through Solar System

Astronomers this week confirmed the discovery of an interstellar object racing through our Solar System – only the third ever spotted, though scientists suspect many more may slip past unnoticed.

Astronomers this week confirmed the discovery of an interstellar object racing through our Solar System – only the third ever spotted, though scientists suspect many more may slip past unnoticed (stock image.) © Unsplash/Justin Wolff

The visitor from the stars, designated 3I/Atlas, is likely the largest yet detected and has been classified as a comet, or cosmic snowball.

"It looks kind of fuzzy," Peter Veres, an astronomer with the International Astronomical Union's Minor Planet Center, which was responsible for the official confirmation, told AFP.

"It seems that there is some gas around it, and I think one or two telescopes reported a very short tail."

Originally known as A11pl3Z before it was confirmed to be of interstellar origin, the object poses no threat to Earth, said Richard Moissl, head of planetary defense at the European Space Agency.

"It will fly deep through the Solar System, passing just inside the orbit of Mars," but will not hit our neighboring planet, he told AFP.

Excited astronomers are still refining their calculations, but the object appears to be zooming more than 60 kilometers (37 miles) a second.

This would mean it is not bound by the Sun's orbit, unlike objects that remain within the solar system.

Its trajectory also "means it's not orbiting our star, but coming from interstellar space and flying off to there again," Moissl said.

"We think that probably these little ice balls get formed associated with star systems," added Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics. "And then as another star passes by, tugs on the ice ball, frees it out. It goes rogue, wanders through the galaxy, and now this one is just passing us."

The object is currently estimated to be roughly 10-20 kilometers wide, Moissl said, which would make it the largest interstellar interloper ever detected. But the object could be smaller if it is made out of ice, which reflects more light.

ESA's astronomers are actively tracking 3I/ATLAS, which is now the third confirmed interstellar comet to pass through our Solar System!

More info at: https://t.co/ARzYu9snS8 pic.twitter.com/jNYriTvluC

— ESA Operations (@esaoperations) July 3, 2025

Veres said the object will continue to brighten as it nears the Sun, bending slightly under the pull of gravity, and is expected to reach its closest point – perihelion – on October 29.

It will then recede and exit the Solar System over the next few years.