For centuries mariners have returned from sea with strange reports of a glowing ocean. The phenomenon, deemed the "milky seas effect," is the eerie stuff of legend, even garnering mention in Jules Verne's "Twenty Thousand Leagues Under the Sea."
According to the bizarre reports, large swathes of open ocean, which appear normal by day, radiate with an eerie haze by night. The light does not come from the moon or stars; it comes from the sea itself.
It wasn't until 1995 that a merchant vessel decided to investigate. After collecting water samples, researchers concluded the glowing ocean was likely due to a bloom of tiny bioluminescent organisms, teeming across thousands of square miles.
This composite satellite image shows the milky sea and the region of the ocean where it was spotted. It is not an algal bloom in the strictest sense, but rather bacteria following in the aftermath of a suspected algal bloom.