Astronomers have just confirmed the discovery of the third interstellar object ever spotted making its way through our Solar System. Named 3I/Atlas (previously known as A11pl3Z), it’s probably the largest interstellar visitor we've seen so far—estimated to be between 10 and 20 kilometers wide, with a faint “fuzziness” that hints it’s mostly made of ice, classifying it as a comet.
This intriguing object was discovered last week by the NASA-funded ATLAS survey in Hawaii, and observatories around the globe quickly confirmed its existence. Astronomers even traced its path back to mid-June using older images. Right now, it’s about 3.8 astronomical units away from Earth—roughly the same distance as Jupiter—and it’s zooming through the Solar System at over 60 kilometers (37 miles) per second, moving too fast to be captured by the Sun’s gravity.
“It’s not orbiting our star; it’s coming from interstellar space and will be heading back out there again,” said Richard Moissl, who leads planetary defense at the European Space Agency. The comet will pass just inside Mars’s orbit in early October, but there’s no need to worry—it poses no threat to Earth or the Red Planet.
This rare visitor gives scientists a fantastic opportunity to study material from another star system. If they find organic compounds, such as amino acids, it could bolster the argument for life-friendly conditions beyond our Solar System.
3I/Atlas joins two previously confirmed interstellar objects: ‘Oumuamua (2017), a mysterious, elongated body that still sparks debate about its nature, and Comet 2I/Borisov (2019), which looked a lot like comets we have in our system.
Anticipation is growing for upcoming observations. As it approaches the Sun in late October, the comet will brighten, making it easier to study with powerful tools like the James Webb Space Telescope and the Vera C. Rubin Observatory, which is expected to help discover many more such objects in the years ahead.
Astronomers estimate there could be thousands of interstellar objects drifting unnoticed through the Solar System at any given time—each a wandering messenger from distant stars, offering a tantalizing glimpse into the broader galaxy beyond.