Well, let me tell you that basically there has been a legend or folklore amongst the sailors who have sailed across the Indian Ocean that sometimes at night, and for miles around, they could see the sea glowing in a bright white light and hence the term– glowing milky seas.
To date it was mostly believed that it is perhaps a mysterious phenomenon which has not been proved scientifically and perhaps does not even exist, something similar to, say, the Loch Ness Monster or the Bermuda Triangle mystery.
But it was only about a decade ago- eleven years to be precise- that two scientists finally discovered what could be a possible scientific explanation of this phenomenon, as well as a proof of its authenticity.
This phenomenon has been existence for nearly past 400 years and there have been sightings of this nature where sailors have experienced sailing in milky seas at night. One such vessel was S.S. Lima which sailed somewhere around the coast of Somalia more than 11 years ago.
Steve Miller and Steve Haddock, the two scientists, actually traced satellite images of the Indian Ocean of the time when the ship had actually traversed the region, and actually found it on the satellite map itself. The hypothesis put forward by them for the explanation of this phenomenon is explained below. You can also see the satellite imagery of this phenomenon in the adjacent image. (Click image to enlarge.)
Possible Explanation for the Legend of the Milky Seas
As per the research of Miller and Haddock, the phenomenon of glowing seas can be attributed to bioluminescent bacteria, which need to be present in huge quantities (40 billion trillion) in order to produce continuous light and the milky seas glowing effect. To get an idea of the numbers involved, Haddock says to just imagine that the entire layer of the Earth’s surface is covered with grains of sand up to four inches thick. The number of sand grains in such a layer would be equivalent to nearly 40 billion trillion.
The reason for so many bacteria to gather at one place and time is to attract fish that would arrive there and the bacteria would then deposit themselves into their gut and continue to exist over time.
The Concept of Bioluminescence
The process of bioluminescence (from the Greek bios for "living" and the Latin lumen "light") refers to the ability of bioorganisms to produce light. This light is produced in bioluminescent animals like krill, lightning bugs, and the common glowworm because the electrons jump from a state of high energy to a state of low energy, and the energy difference between the two states is dissipated in the form of light, instead of heat.
Normally the color of such bio-light is blue, but since the human vision receptors have their limitations, it appears as white color during night, which is the cause of this effect as observed for past few centuries by sailors from all parts of the globe.
Yet, this mystery will only be considered to be fully solved when further study is done on this phenomenon. The same scientists are also planning to send a scientific research vessel into the region to find out more about it. It is also worth noting that such sightings are mostly done in the Indian Ocean region, which also needs to be analyzed.
Hence it can be stated that finally the veil of mystery over the four centuries old phenomenon seems to be lifting somewhat.
P. J. Herring, M. Watson, Milky seas: a bioluminescent puzzle, Mar. Obsvr, Vol: 63, pp. 22-30, 1993
K. H. Nealson, J. W. Hastings, Bacterial bioluminescence: its control and ecological significance, Microbiological Reviews, Vol: 43, pp. 496-518, 1979
Image from S. D. Miller, S. H. D. Haddock, C. Elvidge, T. F. Lee, Detection of a bioluminescent milky sea from space, Proceedings from the Natural Academy of Science, Vol 102, No 40, pp. 14181-14184, 2005.