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Science|It Came From Outside Our Solar System, and It Might Be Big
https://www.nytimes.com/2025/07/02/science/interstellar-object-a11pi3z.html
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A11pI3Z is only the third interstellar visitor to be discovered, and astronomers can’t say yet whether it is a comet or a rocky body.
July 2, 2025, 5:44 p.m. ET
For only the third time, astronomers have found something passing through our solar system that looks like it came from outside the solar system.
This interstellar object, with a temporary, cumbersome designation of A11pI3Z, is still pretty far from the sun, located between the orbits of the asteroid belt and Jupiter.
The first known interstellar object was Oumuamua, which raced through the solar system in 2017. In 2019, Borisov, a comet of interstellar origin, passed by.
On Tuesday, a telescope in Chile spotted what initially looked like an unknown asteroid on a highly eccentric path that might come close to Earth’s orbit. The telescope is one of five around the world that are part of the Asteroid Terrestrial-impact Last Alert System, or ATLAS, which is a NASA-funded project that watches for space rocks that might be on a collision course with our planet.
The observation was submitted to the International Astronomical Union’s Minor Planet Center, which maintains a catalog of small space bodies in the solar system. Other skywatchers quickly took a look.
“Follow-up observations on July 1 and 2 began to reveal that its orbit might be unusual, possibly interstellar,” said Larry Denneau, a co-principal investigator for ATLAS, which was developed by the University of Hawaii.
