Great Barrier Reef
May 13, 2003
The above image was acquired by the Landsat-7 Enhanced Thematic Mapper plus (ETM+) sensor on August 14, 1999. This is a natural color composite satellite image made using red, green, and blue wavelengths. The islands and coral reefs that form the Great Barrier Reef resemble misshapen blue pearls, stretching more than 2,000 km (1,200 miles) along the Queensland coast of Australia (at left). In October of 1981, the Great Barrier Reef was inscribed on the World Heritage List. It's the world's most extensive reef system, and the biggest structure made by living organisms on Earth. To the north, the reef is virtually continuous, while in the south (as shown above), individual reefs are more common.