The ocean is the most unexplored part of the planet. Not even 10% has been explored to date, and it hides many secrets that humanity may never be able to solve. For over 400 years, researchers have been navigating the seas, making maps and creating trade routes for boats, but they couldn’t stop and analyze what was going on under the surface due to the limitations of their time. Now, as we are able to reach the deepest point in the sea in special occasions, scientists have found out about the ocean glowing at night.
How water filled our ocean: A billion years process
The water covering our planet has been around since the early stages of Earth’s formation. The most accepted theory is that water was brought in by asteroids – which commonly carry the h2o formula – during the impacts that created the “blue planet” as we know it. But things were very different in that time – seas covered deserts, and many cities we know live in were once underwater.
Recently, scientists have found out that the ocean glow at night, but not for the same reason that it makes the water look blue. The delicate ecosystem needs to be in the perfect conditions for it to glow. Some fish are able to shine due to their bioluminescence, but only in deep, dark waters where sunlight cannot reach. Thankfully, other species have this ability near the surface.
Sailors saw the sea changing colors hundreds of years ago
For more than 400 years, sailors have told tales of the ocean that seem to glow across vast stretches of water. Today, we call this rare spectacle “milky seas,” but centuries ago, it was the stuff of legend, whispered in stories passed down through generations. Now, scientists are beginning to understand these mysterious lights and are working towards predicting when and where they might appear.
Justin Hudson, a doctoral student at Colorado State University in the department of atmospheric science, has collected over 240 documented sightings – including historical accounts from sailors like Brunskill and Price – into a new database. This effort could one day allow researchers to guide vessels directly to a glowing sea for firsthand study, as found in a study shown in Earth and Space Science.
It can be seen from space
Hudson explains that studying these events could reveal a lot about ocean ecosystems. For example, milky seas might indicate either a thriving or struggling marine environment, but the details are still unclear. By tracking these glowing waters, experts wish to better understand their role in Earth’s interconnected ocean systems.
Sailors often compare the glow of milky seas to the soft light of glow-in-the-dark stars on a child’s bedroom ceiling. In some cases, the light is so bright that it’s reportedly strong enough to read by, a big difference to the dark expanse of open water when neither sun nor moon is present. These events can stretch across areas as large as 100,000 square kilometers – roughly 39,000 square miles – and the largest ones have been observed from space.
No one knows why the bacteria shines this brightly
While the exact cause remains a mystery, researchers believe the glow is likely produced by high concentrations of microscopic bioluminescent bacteria known as Vibrio harveyi. This is different from the more common blue glow caused by phytoplankton, which light up briefly when disturbed by movement in the water. Scientists theorize that these bacteria might use their glow to attract fish, which then eat the bacteria and help them keep going inside the fish’s gut. As researchers are investigating the seas more often to find new, renewable sources of energy, discoveries like this can become “normal” in the future.
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