For centuries, sailors have described navigating eerie night waters lit by a mysterious glow, but such “milky seas” have long eluded scientific inquiry due to their remote, transient and rare nature. “I would say there are only a few people alive right now who have seen one. They’re just not very common — maybe up to one or two a year worldwide — and they’re usually not near the coast, so you have to be in the right place at the right time,” said Steven Miller, professor of atmospheric science at Colorado State University in Ft. Collins. Milky seas are thought to be triggered by bioluminescent bacteria communicating with each other, possibly in response to changes in ocean currents caused by atmospheric conditions. Miller has been chasing them for decades, jealously listening to rare first-hand accounts and searching for scientific evidence to confirm their existence, as well as a means to see and study the phenomenon himself. “It’s a really huge and mysterious response in our biosphere. We would like to know how it works and how it might change in a changing climate,” he said. A night photo of a bioluminescent milky sea taken on the night of August 2, 2019. The ship’s deck is silhouetted against the water’s glow. Photo: Steven Miller, Leon Schommer (photographer) and Naomi McKinnon, Australian National University, Canberra Over the past decade, low-light imaging equipment aboard newer environmental satellites has provided Miller with some tantalizing results. Now, eyewitness testimony from Ganesha sailors has provided the first surface confirmation that these satellite images are indeed milky seas – as well as the first real images of the phenomenon. From late July to early September 2019, US National Oceanic and Atmospheric Administration satellites recorded what Miller believed could be a bioluminescent event south of Java, Indonesia, spanning more than 100,000 square kilometers (38,600 square miles). In July 2021 he published images of the event – plus 11 other possible milky sea cases – in Nature Scientific Reports. Media coverage of this investigation prompted Naomi McKinnon, a member of Ganesha’s crew of seven, to contact Miller and describe the events they experienced on the night of August 2, 2019. The crew had been on a round-the-world voyage when the Ganesha struck a patch of bright water between Lombok, Indonesia, and the Cocos (Keeling) Islands in the eastern Indian Ocean at about 9:00 p.m. The yacht suddenly entered these glowing waters and the whole experience lasted until dawn. A crew member told Miller that the color and intensity of the glow was “similar to stars or glow-in-the-dark stickers.” The yacht’s captain said the glow appeared to originate about 10 meters below the surface of the water, rather than a thin surface film as some scientists had imagined. Lowering a bucket into the water revealed several spots of steady light that darkened when stirred — the opposite of what happens with “normal” bioluminescence, said Miller, whose findings are published in the Proceedings of the National Academy of Sciences. Photos taken by the crew on a smartphone and digital camera provided the first photographic evidence of a milky sea, he added. “At this point it’s all word of mouth, dating back to the early days of merchant ships in the 18th century. Everyone has described something similar and the photos are consistent with what they described – it’s a sort of uniform, ethereal glow, almost hazy looking, very disorienting.’ Subscribe to First Edition, our free daily newsletter – every day at 7am. BST This independent confirmation will facilitate the study of milky seas in the future. “It means we can now use [satellite images] confidently study the milky seas from space, but also direct research vessels equipped with the right kinds of equipment to sample the water and determine its composition,” Miller said. “The 2019 Java Sea Milky Way appeared to last for at least 45 nights, suggesting that these things aren’t just a dark, one-night event that would make it nearly impossible to get to once a year. We’ve found that once these larger ones are established, they stay for several weeks, if not a few months.”
