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Credit: Terra MODIS NASA Goddard Space Flight Center

What in the world is it?

A badly scratched Polaroid photo? A badly burned negative? No, it’s a Terra MODIS image of chlorophyll (green) in the ocean off the west coast of India (black) on February 3, 2003.

Why is this important? Varying shades of blue and green color tell scientists how much chlorophyll is in the water. Chlorophyll is a pigment that reflects green light, making the ocean water look more green where there is more chlorophyll. Chlorophyll is produced by living single-celled plants in the ocean called phytoplankton. The phytoplankton use chlorophyll to capture sunlight and turn the sun’s energy into food.

Seawater changes from blue to green as the abundance of phytoplankton increases. This is because phytoplankton, like other plants, shed chlorophyll from their cells. Researchers are now using color to determine the overall health of the oceans. Unlike when you get seasick and turn green, when the ocean turns green, it’s feeling pretty good.