Sailors have reported mysterious “milky seas,” or miles-long glowing patches of ocean for centuries. Some researchers have created a database to figure out why they glow. Steven D. Miller/CIRA/CSU and NOAA/NESDIS
Sailors have reported mysterious “milky seas,” or miles-long glowing patches of ocean for centuries. Some researchers have created a database to figure out why they glow.
Steven D. Miller/CIRA/CSU and NOAA/NESDISFor hundreds of years sailors have told stories about miles of glowing ocean during a moonless night.
In 1849, on the Arabian Sea, Captain Kempthorne, described a “most extraordinary phenomenon of the most dazzling brightness, and of highly phosphorescent nature. In fact it looked as if we were sailing over a boundless plain of snow, or a sea of quicksilver.”
Today, this phenomenon is known as “milky seas.” But little is known about the phenomenon. The only scientific sample was collected in 1985.
So atmospheric scientist Justin Hudson, a PhD candidate at Colorado State University used accounts like Kempthorne’s spanning 400 years to create a database of these milky seas reports. This database also includes satellite images that can confirm large swaths of milky seas.
Hudson hopes the database can give researchers a better idea on where and when milky seas occur, so research vessels can take samples of the glowing water.
Hudson’s PhD advisor and fellow atmospheric scientist, Steven D. Miller, says sampling is difficult because milky seas tend to be in remote places.
“About 70% of the world is covered in ocean, and there’s just very few people out in any one given spot,” Miller says.
The one scientific sample pointed towards the bacteria Vibrio harveyi as the cause of the eerie bioluminescence. However, Hudson says this kind of glowing is different from what people may have previously encountered in the wild.
“The more typical bioluminescence you see out on the ocean is caused by this organism called dinoflagellates,” he says. “It glows in response to some kind of shock. Something nudges it or it gets inside a crashing wave.”
Vibrio harveyi produces a constant glow when it reaches a population maximum. Scientists think this phenomenon is supposed to attract predators that will eat them and give them another environment to thrive in: the predators’ stomachs.
Got a question about a scientific mystery? Let us know at shortwave@npr.org.
Listen to Short Wave on Spotify and Apple Podcasts.
Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.
This episode was produced by Rachel Carlson. It was edited by Rebecca Ramirez. Tyler Jones checked the facts. Jimmy Keeley was the audio engineer.