The darkness of interstellar space was pierced on 1 July 2025, when astronomers detected a new visitor from the void. Known as 3I/ATLAS, this interstellar object immediately presented a riddle that has left scientists scrutinising their data. Unlike the steady shine of typical asteroids, the light from this object displayed a rhythmic, pulsating variability.
Every 16.16 hours, the object's brightness shifts significantly, with an amplitude changing by tens of percent. Initial observers were quick to attribute this to the object's physical rotation. They theorised they were watching an elongated nucleus, with an axis ratio of about 0.8, tumbling end-over-end through the cosmos.
