The milky seas effect is maritime folklore that was previously misunderstood. Sailors in the 19th-century have always regarded its origin as something sinister like sea monsters and mermaids. Using satellites, modern scientists have a deeper understanding of the bacteria, not mermaids nor sea monsters, that create this glowing water.
For centuries, the milky seas effect has been maritime folklore that sailors talk about. It is a strange encounter with nature that was likened to seeing sea monsters and mermaids in the past. Crews who have to sail through miles of milky seas were terrified of the glow-in-the-dark waters because of the unknown creatures that emit the steady bright glow.
In the 19th century, Captain Kingman documented his sightings of milky seas that are so remote and elusive that only a few have encountered them. However, modern times have better ways of monitoring them.
Steven D. Miller, a professor of atmospheric science at Colorado State University, wrote in The Conversation that using artificial satellites that study Earth is the new way to detect milky seas. This will hopefully give new insights about these luminous waters and guide future research vessels to reconcile surreal tales with science.
The Tale of Milky Seas
Sailors in the 1800s had no understanding what was generating the milky seas phenomenon and assumed it was caused by something terrible. According to BBC Earth, sailors described the phenomenon as something that looks like milk or clouds that stretch for many square miles.
However, to this day, there is only one documented encounter with the milky sea. They took samples of the glowing water and found that the bacteria called Vibrio harveyi was causing the glow on the water's surface.
Professor Miller wrote that this bacteria works differently than the dinoflagellates that cause bioluminescence close to shore. Instead, it is like a light switch turns on in the luminous bacteria when their population gets large enough at about 100 million individual cells per milliliter of water.
Scientists believe that the purpose of this glow is to attract fish that eat them because they thrive inside the stomachs of these fishes. So, when their population starts growing so much, their food supply also decreases. Thus, the guts of the fish could be an alternative option.
Now, milky seas can easily be spotted using artificial satellites that study Earth. Biologists know that milky seas could be happening in many parts of the oceans all the time, and using satellites will help them track and monitor these glowing phenomena.
Milky Seas Observed by Satellites
Milky seas are elusive and almost impossible to sample. It takes a special instrument for scientists to detect the light from them, which is 100 million times fainter than the daylight as seen by satellites.
Professor Miller wrote that he and his colleagues first explored the potential of using artificial satellites in 2004 when they used the U.S. defense satellite imagery to confirm the presence of a milky sea that was reported in 1995. Their paper, titled "Detection of a Bioluminescent Milky Sea From Space," was published in PNAS.
However, they had to wait for more years for a better instrument that will let them see the milky seas effect. In 2011, the Day/Night Band instrument went live for NOAA's new constellation of satellites.
It took them years to interpret what they saw using the instrument until, in 2018, they saw an odd-shaped feature that appeared offshore in Somalia.
It was the 'aha!' moment they have been looking for, for many years. It was a glowing swirl in the ocean that spanned over 40,000 square miles (100,000 square kilometers) or almost the size of Kentucky.
Satellite imaging provided them great detail and clarity of the milky seas effect. They were able to learn how milky seas are related to sea surface temperature, currents, and biomass. They found that there are approximately 100 billion trillion cells in the milky seas, which is the total estimated number of observable stars in the universe.
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