An interstellar comet called 3I/ATLAS just swung past the Sun, and astronomers say it’s spewing water vapour at a staggering rate.It’s only the third confirmed object from another star system to ever pass through ours.The Neil Gehrels Swift Observatory caught it glowing bright blue and releasing hydroxyl gas a chemical trace left when ultraviolet light breaks water molecules apart.That reaction proved the comet isn’t just icy; it’s actively venting water, behaving like a small, natural sprinkler system in deep space.The outflow shocked researchers because of how far it still is from the Sun — much farther than where comets usually heat up.
🔗 NASA Science – Comet 3I/ATLAS
As it made its closest pass around October 30 2025, its tail stretched across millions of kilometres, visible through mid-size telescopes in the predawn sky.
No threat to Earth it’s cruising roughly 1.8 astronomical units away but it’s offering a once-in-a-lifetime look at material born under another sun.
Scientists are now analysing how its isotopes and composition differ from our local comets, which could reveal what early planetary systems were made of.
When it finally fades, 3I/ATLAS will keep flying back into interstellar space carrying its story beyond our sky.