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.
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