Astronomy Picture of the Day

Explanation: What is causing the water in Florida Bay to turn black? The mysterious black colour could be seen as early as last December in images taken by the SeaWIFS instrument on board the Earth-orbiting SeaStar satellite. During the darkest period in February, when the above image was taken, visibility in the usually transparent/turquoise water dropped below three metres. Samples have been taken and are currently being analyzed. Early tests show the black water has normal salinity and oxygen and might be an unusual nontoxic algae bloom. Whatever the cause, the black water has real ecological and economic consequences, as normally abundant fish are completely absent. More recent SeaWIFS images show the black water to be breaking up into smaller pockets.