The solar system’s newest visitor, 3I/ATLAS, may be 3 billion years older than the sun and its planets.
First discovered on July 1, 3I/ATLAS is a rare interstellar object — only the third ever spotted. Since then, astronomers have been racing to uncover its origins. A new calculation predicts that 3I/ATLAS originated from a part of the Milky Way called the thick disk. If so, there’s a two-thirds chance that it’s a comet over 7 billion years old. That would make it the oldest comet known, researchers reported July 11 at the Royal Astronomical Society’s National Astronomy Meeting 2025 in Durham, England.
Interstellar objects don’t come with “a label that you can just read,” says study coauthor Chris Lintott, an astrophysicist at the University of Oxford. “All we really know is the direction it’s coming in, and to go from that to say anything about the age is really rewarding.”
Others caution that more data are required to confirm the object’s origin and age.
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