Taken this past July by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imaging instrument on board NASA's Terra spacecraft, this picture shows the Grand Canyon from above. The canyon, carved by the Colorado River, exposes nearly two billion years of Earth's history in its walls. ASTER is a joint project of the United States and Japan and is collecting detailed information about the Earth's surface. Earlier this week, the two countries released the most detailed digital topographic map
of the planet to date.