Depending on your definition, there are 2,000 to 400,000 islands in the world. Some rival the size of continents—Greenland and Indonesia—while others barely stick a kilometer or two of beach out of the sea. Together they shelter unique plant and animal species and nearly 500 million humans. Some islands are formed by volcanism, with molten rock emerging from Earth's interior to build seafloor mountains that eventually rise above the water surface. Others are chunks of continental crust that became surrounded by water when sea levels rose at the end of the last Ice Age. Life itself has created a few, from artificial islands made by humans to sandbar-topped reefs built by corals. With the space station and a fleet of satellites, NASA has seen all of them. Check out the images for a look at five islands viewed from orbit.
Islands take many forms—from sand-covered reefs to forested volcanic rocks—all of them beautiful.
Cat Island in the Bahamas has been proposed as the possible first landfall for Christopher Columbus in the New World.
The ring-shaped Atafu Atoll is a result of coral reefs building around a central volcanic island in the South Pacific that has since subsided.
Tahiti consists of two old volcanoes linked by an isthmus. Heavy rains have carved deep valleys and watered the lush vegetation.
Mataiva means “nine eyes” in Tuamotuan, a Polynesian language. It's an allusion to the nine thin channels leading to the atoll's central basin.
Called “the Gathering Place,” O’ahu is home to 75 percent of Hawaii’s population and some of the world's best surfing.
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NASA's Earth Observatory
Cover image courtesy of NASA/JSC/Gateway to Astronaut Photography of Earth
Cat Island image courtesy of NASA/JSC/Gateway to Astronaut Photography of Earth
Atafu Atoll image courtesy of NASA/JSC/Gateway to Astronaut Photography of Earth
Tahiti image courtesy of NASA Earth Observatory/Jesse Allen and Robert Simmon
Mataiva image courtesy of NASA/JSC/Gateway to Astronaut Photography of Earth
O'ahu image courtesy of NASA/GSFC/METI/ERSDAC/JAROS and the U.S./Japan ASTER Science Team
- Mike Carlowicz (Sigma Space Corporation) [Lead]