Coral bleaching? What's that?!
A reef is a big group of rocks on the ocean floor, but did you know that a coral reef is actually alive and covered with very small animals called corals? These animals glue their tiny skeletons to rocks, so they end up staying in the same place their entire life!
Coral reefs are very sensitive to light and temperature. If the water they live in gets too hot, they might not survive. They also don't like it when the ocean has too much pollution. Sometimes, storms can even upset coral depending on how often they happen and how severe they are. If coral reefs are under too much stress, like in these conditions, they can eject the algae living on them and turn completely white. This is known as coral bleaching. This does not necessarily mean the coral is dead - corals can survive bleaching! They do become more vulnerable to death however, especially if the stress continues for a long period of time.
NASA recently developed some very sensitive instruments to study coral reefs from an airplane flying above the ocean. The COral Reef Airborne Laboratory (CORAL) uses an instrument called the Portable Remote Imaging Spectrometer (PRISM) to see the condition of reefs. Scientists will now be able to monitor these reefs and their health. They will be able to measure the amounts of coral, algae, and sand on the ocean floor!