Astronomers observing the wandering interstellar comet 3I/ATLAS have discovered that this rare visitor is releasing water at an astonishing rate — almost as if it were a high-pressure cosmic fountain.
This is a Hubble Space Telescope image of the interstellar comet 3I/ATLAS. Hubble photographed the comet on July 21, 2025, when the comet was 277 million miles from Earth. Hubble shows that the comet has a teardrop-shaped cocoon of dust coming off its solid, icy nucleus. Because Hubble was tracking the comet moving along a hyperbolic trajectory, the stationary background stars are streaked in the exposure. Image courtesy – NASA
A team at Auburn University, Alabama, used NASA’s Neil Gehrels Swift Observatory to examine the comet’s spectral fingerprints and found strong traces of hydroxyl (OH) gas. Hydroxyl molecules appear when sunlight breaks apart water vapor, which means the comet’s surface is actively venting large amounts of ice that have been trapped since its formation.
The findings, published in The Astrophysical Journal Letters, suggest that 3I/ATLAS is built very differently from the frozen bodies that orbit within our own solar system. While typical comets follow predictable paths and display familiar compositions, this interstellar traveler — only the third of its kind ever identified — appears to contain ices and volatiles forged around another star.
Researchers believe studying these outbursts offers a rare glimpse into material from beyond the Sun’s gravitational neighborhood, helping scientists compare how planetary systems form across the galaxy.
