By the Light of the Sea

January 25, 1995: On a dark evening in the Arabian Sea off the coast of Somalia, a merchant vessel was steaming southward when its crew began to notice a strange glow in the distance. Within minutes, and for six hours thereafter, the S.S. Lima found herself cutting through waters producing a radiant white glow reminiscent of a boundless snowfield. Ten years later, scientists learning of Lima’s surreal encounter sought out the date and time within an archive of low-light satellite data. The match found between the ship’s position and an “anomalous” light source in the satellite data — spanning an area exceeding 15,000 km2 and morphing over several night’s time in a way consistent with the known sea surface currents — marked the first confirmed remote-sensing of the legendary “milky sea,” a poorly understood phenomenon thought to be linked to population explosions of luminous bacteria. Here, we detail the unusual circumstances and important implications of this discovery.