Carnegie Lake, Australia, 1999 Carnegie Lake in Western Australia fills with water only during periods of significant rainfall. In dry years, it is reduced to a muddy marsh. Flooded areas appear dark blue or black, vegetation appears in shades of dark and light green, and sands, soils and minerals appear in a variety of colors. NASA hide caption

itoggle caption NASA

A replica Mayan Calendar Round showing the date September 21, 2004, opening day for the Smithsonian's National Museum of the American Indian. Molly Stephey/Smithsonian's National Museum of the American Indian hide caption

itoggle caption Molly Stephey/Smithsonian's National Museum of the American Indian

NASA's Mars rover Curiosity cut a wheel scuff mark into a wind-formed ripple at the "Rocknest" site to give researchers a better opportunity to examine the particle-size distribution of the material forming the ripple. The rover's right Navigation camera took this image of the scuff mark on the mission's 57th Martian day. NASA/JPL-Caltech hide caption

itoggle caption NASA/JPL-Caltech

Navy specialists repair a weather buoy collecting data for the National Oceanic and Atmospheric Administration (NOAA) off the Atlantic coast of Africa. President Richard Nixon, a Republican, created NOAA, one of our principal resources for understanding the Earth's climate. Elizabeth Merriam/U.S. Navy hide caption

itoggle caption Elizabeth Merriam/U.S. Navy

Spectators Mario Vasquez, 40, of Redondo Beach and his son Mario Jr., 2, watch as space shuttle Endeavour, atop NASA's Shuttle Carrier Aircraft, prepares to land at Los Angeles International Airport Friday. Ringo H.W. Chiu/AP hide caption

itoggle caption Ringo H.W. Chiu/AP

Space shuttle Endeavour, attached to a 747, on the tarmac at the Kennedy Space Center in Florida. Bill Ingalls/NASA /UPI /Landov hide caption

itoggle caption Bill Ingalls/NASA /UPI /Landov

The Soyuz capsule lands with Commander Gennady Padalka of Russia, NASA Flight Engineer Joe Acaba and Russian Flight Engineer Sergei Revin aboard, near the town of Arkalyk, Kazakhstan. The capsule's final meter of descent is eased by braking engines. Carla Cioffi/NASA hide caption

itoggle caption Carla Cioffi/NASA