Photos: Satellites keep close watch on coral reefs
This MODIS (Moderate Resolution Imaging Spectroradiometer) image shows the location of coral bleaching at Heron Island within the Capricorn Bunker Group of the Great Barrier Reef. NASA's Terra and Aqua satellites monitor the reefs for surface temperature and color, and can post data online within three hours of passing over the reefs.
Rising ocean temperatures force out the algae that live in coral and give it its remarkable coloration. Scarla Weeks, a researcher at the University of Queenland, said, "Sea surface temperatures over the last five months are actually higher in certain locations now than they were in 2002 when we witnessed the worst bleaching incident to date."