Interstellar comet 3I/ATLAS safely passes Earth, continues toward Jupiter

The interstellar comet 3I/ATLAS safely passed Earth this morning, reaching its closest point at roughly 06:00 GMT at a distance of 168 million miles (270 million kilometers). Scientists said the object is now racing toward Jupiter, with a close approach planned at about 33 million miles (53 million kilometers) on March 16, 2026. After that, 3I/ATLAS will travel past Saturn’s orbit in July 2026, cross Uranus’s orbit in June 2027, and in 2028 pass Neptune’s orbit at speeds around 137,000 miles per hour (221,000 kilometers per hour). The journey is expected to continue until the object reaches Pluto’s orbit in April 2029, before continuing back into interstellar space in the mid-2030s.

Discovered on July 1 by the NASA-funded ATLAS telescope in Chile, 3I/ATLAS is only the third confirmed object that formed around another star to be detected entering our solar system. Tracing its trajectory revealed that the visitor originated from outside the solar system, a finding confirmed after observations from multiple ground- and space-based assets. It is believed to be about eight billion years old, making it older than the Sun and the rest of the planets.

As 3I/ATLAS moves closer to the Sun, the comet’s outer layers — ice and dust — vaporize to form a coma and sometimes long tails. The degree of activity has increased as it draws nearer to the Sun, revealing layers of the comet’s surface that have been altered by billions of years in interstellar space. In describing the object’s makeup, Professor Chris Lintott of the University of Oxford said researchers have detected carbon monoxide, water and traces of nickel, adding that the data are still being interpreted as the comet evolves under solar heating. “We’ve been scrambling to observe 3I/ATLAS with everything we’ve got since it was discovered,” Lintott said. “So far, it’s a fairly normal, active comet.”

The observation campaign has included spacecraft normally used for other purposes. NASA repurposed orbiters around Mars to help capture spectra and track the evolving coma, while Earth-based and space-based telescopes have oriented toward the object to gather data on its composition and behavior, which is consistent with conventional cometary activity rather than any artificial construct. Dr. Matthew Genge, a near-Earth-objects and astrobiology expert at Imperial College London, noted that the idea the object is an alien spacecraft has been decisively ruled out based on the observed chemistry and outgassing patterns. “Suggestions that 3I/ATLAS was an alien spacecraft on route to Earth have thus been shown to be very wrong indeed,” he said.

The broader takeaway for scientists is not only learning about a body that formed around a distant star but also refining strategies for spotting and studying future interstellar visitors. Researchers say interstellar objects are not rare in the galaxy—astronomers estimate there are roughly a billion billion billion such objects in the Milky Way—but they are exceptionally hard to detect. The Vera C. Rubin Observatory and other next-generation survey instruments are expected to increase the rate of discovery, enabling researchers to gather more data about the composition and history of these travelers.

Some experts see potential benefits in preparedness for future interstellar arrivals. Professor Mark Burchell, a space scientist at the University of Kent, suggested that having a spacecraft positioned in space to intercept such objects could dramatically boost scientific return. “The next science goal to my mind is to prepare to see a ‘fresh’ comet from the outer solar system, which means parking a spacecraft in space in advance,” Burchell said. He cautioned that catching interstellar objects presents different challenges than catching native comets, given their rarity and high relative speeds. Still, the prospect of direct in-situ study of material from another star system could be transformative for our understanding of planetary formation.

The current passage of 3I/ATLAS through the inner solar system offers a rare window into material that formed billions of years before our Sun. Astronomers emphasize that, despite occasional speculation, there is no evidence the object is anything other than a long-period comet heated by the Sun. As it continues its voyage, scientists will continue to analyze data from both terrestrial and space-based facilities to refine models of interstellar body formation and evolution, and to improve readiness for the next visitor from beyond the solar system.