Japan’s X-ray astronomy satellite XRISM, developed by JAXA in collaboration with NASA, has achieved a groundbreaking milestone:the world’s first X-ray detection from an interstellar object, 3I/ATLAS. Using its wide-field soft X-ray imager Xtend, XRISM captured a faint X-ray glow stretching nearly 400,000 kilometers from the object—an observation that opens a new window into the physics of interstellar bodies.