NASA Spinoff  Then Why Do They Call Earth the Blue Planet?
While the most common photographs of Earth taken from space show
the planet covered in blue water, NASA has managed to produce
detailed color images, using satellite imagery, that show the
remarkable variation of colors that actually make up the oceanic
surface. An ocean's color is determined by the interaction of
surface waters with sunlight, and surface waters can contain any
number of different particles and dissolved substances, which
could then change the color.  The particles are mostly
phytoplankton the microscopic, single-celled ocean plants that
are the primary food source for much marine life. Remote
detection of phytoplankton provides information about the uptake
and cycling of carbon by the ocean through photosynthesis, as
well as the overall health of the water. Inorganic particles and
substances dissolved in the water also affect its color,
particularly in coastal regions. Satellite images can be used to
calculate the concentrations of