By Gizem Nisa Demir
ISTANBUL (AA) – Interstellar comet 3I/ATLAS is releasing water at an astonishing rate, gushing like a “fire hose running at full blast,” according to a new study that offers rare insight into how planets form beyond the solar system.
Scientists using NASA’s Neil Gehrels Swift Observatory detected the ultraviolet signature of hydroxyl — a chemical product of water molecules broken down by sunlight — between July and August 2025. The comet was then about 2.9 times farther from the sun than Earth.
The study, published in the Astrophysical Journal Letters last month, estimated that 3I/ATLAS is losing nearly 40 kilograms of water every second — far more than scientists expected at such a distance.
“When we detect water — or even its faint ultraviolet echo, OH — from an interstellar comet, we’re reading a note from another planetary system,” said Dennis Bodewits, a physics professor at Auburn University.
“It tells us that the ingredients for life’s chemistry are not unique to our own,” he said in a statement on Tuesday.
- ‘Rewriting what we thought’
Researchers believe the comet’s intense activity may come not from its surface but from icy debris surrounding it. Observations from Gemini South and NASA’s Infrared Telescope Facility suggest that chunks of ice in the coma act like miniature steam vents when hit by sunlight.
“Every interstellar comet so far has been a surprise,” said Zexi Xing, postdoctoral researcher at Auburn University and lead author of the study. “‘Oumuamua was dry, Borisov was rich in carbon monoxide, and now ATLAS is giving up water at a distance where we didn’t expect it. Each one is rewriting what we thought we knew about how planets and comets form around stars.”
After fading from Swift’s view, 3I/ATLAS was spotted in early October by the European Space Agency’s Mars orbiters and will next be tracked by the agency’s Jupiter Icy Moons Explorer (JUICE) in November.
Scientists expect JUICE’s observations — capturing the comet near its closest approach to the sun — to provide the clearest look yet at its watery outflow, though data may not arrive until February 2026 due to communication constraints.