Interstellar Comet 3I/ATLAS Spews Water

Imagine a comet from another star system, spewing so much water it could fill

an Olympic pool in seconds. That’s 3I/ATLAS, an interstellar visitor that swept

past our Sun in late 2025. When sunlight smashes into its ice, hydrogen atoms break

free, shining in ultraviolet light. SOHO’s SWAN camera caught this glow,

allowing scientists to calculate the comet's immense water output—317 followed by 27 zeros

of molecules per second at one point. These observations were crucial as they revealed the

comet’s activity after its closest pass to the Sun. By early December, water production

fell sharply, a familiar pattern for Solar System comets as they cool down farther from