During Tokyo's Hotaru Festival lately 100,000 illuminated blue LEDs were released in the city's river. The solar-powered spheres bobbed their way down the river, drawn in the flow. They looked like the milky way or the freaky phosphorescence you can encounter in southern oceans. The glowing spheres were later caught downstream by giant nets although I like to think that one or two got away and are now exploring the Pacific.
Fig 1.
Fig 2. Photos by jeremy v, makure and ajpscs.
