Interstellar Comet 3I/ATLAS speeded through the Solar System by Jupiter-bound spacecraft

Interstellar Comet 3I/ATLAS speeded through the Solar System by Jupiter-bound spacecraft

By Jackie Flynn Mogensen edited by Claire Cameron

In late 2025, a mysterious comet flew between the orbits of Earth and Mars, reaching a speed of more than 150,000 miles per hour during its closest approach to the Sun. The rare interstellar guest to our solar system caught the attention of astronomers, and many trained their observations on it in an attempt to understand exactly what it is, why it is here, and where it might be going.

Each new piece of data provides a glimpse into space beyond our solar system. And as the comet, called 3I/ATLAS, whizzes through our cosmic neighborhood, space agencies have assembled spacecraft to observe it as it passes. The European Space Agency’s Jupiter-bound spacecraft is no exception: a new image of the comet captured in November by the Jupiter Icy Moons Explorer, or JUICE, reveals that it is almost egg-shaped, with a cloud of gas obscuring its central nucleus, or nucleus.

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“Although 3I/ATLAS is a visitor from interstellar space, traveling from outside the solar system, its behavior is entirely in line with what is expected of a ‘normal’ comet,” the agency said in a statement.

“Nobody knows where the comet came from,” David Jewitt, director of the Institute for Planets and Exoplanets at the University of California, Los Angeles, said in a statement last year. “You can’t project it back with any accuracy to find out where it started on its path.”

Comet 3I/ATLAS has puzzled and excited scientists since it was first spotted in July 2025. Its extraordinary speed at the time — 137,000 miles per hour — and strange orbit indicated it must have been traveling through interstellar space for possibly billions of years, according to NASA. Only three interstellar objects have ever been detected passing through our solar system. And despite efforts to observe it as it passes, Comet 3I/ATLAS remains a mystery.

“It’s like glimpsing a rifle bullet for a thousandth of a second,” Jewitt said in the same statement.

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