Like rivers of liquid water, glaciers flow downhill, with tributaries joining to form larger rivers. But where water rushes, ice crawls. As a result, glaciers gather dust and dirt, and bear long-lasting evidence of past movements. Alaska's Susitna Glacier revealed some of its long, grinding journey when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite passed overhead on Aug. 27, 2009. This satellite image combines infrared, red and green wavelengths to form a false-color image. Vegetation is red and the glacier's surface is marbled with dirt-free blue ice and dirt-coated brown ice. Infusions of relatively clean ice push in from tributaries in the north. The glacier surface appears especially complex near the center of the image, where a tributary has pushed the ice in the main glacier slightly southward. Susitna flows over a seismically active area. In fact, a 7.9-magnitude quake struck the region in November 2002, along a previously unknown fault. Geologists surmised that earthquakes had created the steep cliffs and slopes in the glacier surface, but in fact most of the jumble is the result of surges in tributary glaciers. Glacier surges--typically short-lived events where a glacier moves many times its normal rate--can occur when melt water accumulates at the base and lubricates the flow. This water may be supplied by meltwater lakes that accumulate on top of the glacier; some are visible in the lower left corner of this image. The underlying bedrock can also contribute to glacier surges, with soft, easily deformed rock leading to more frequent surges. Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science
Apollo 8, the first manned mission to the moon, entered lunar orbit on Christmas Eve, Dec. 24, 1968. That evening, the astronauts--Commander Frank Borman, Command Module Pilot Jim Lovell, and Lunar Module Pilot William Anders--held a live broadcast from lunar orbit, in which they showed pictures of the Earth and moon as seen from their spacecraft. Said Lovell, "The vast loneliness is awe-inspiring and it makes you realize just what you have back there on Earth." They ended the broadcast with the crew taking turns reading from the book of Gen
esis. Visit the Apollo 8 page for audio and video of the historic mission. Image Credit: NASA
The Antarctic ozone hole reached its annual maximum on Sept. 12, 2008, stretching over 27 million square kilometers, or 10.5 million square miles. The area is calculated using data from the Ozone Monitoring Instrument on NASA's Aura satellite. This is considered a "moderately large" ozone hole, according to NASA atmospheric scientist, Paul Newman. And while this year«És ozone hole is the fifth largest on record, the amount of ozone depleting substances have decreased about 3.8% from peak levels in 2000. The largest ozone hole ever recorded occurred in 2006, at a s
ize of 10.6 million square miles. NASA has been monitoring the status of the ozone layer through satellite observations since the 1970s.
This picture of the Earth and Moon in a single frame was taken by the Galileo spacecraft from about 3.9 million miles away. Antarctica is visible through clouds (bottom). The Moon's far side is seen; the shadowy indentation in the dawn terminator is the south pole Aitken Basin, one of the largest and oldest lunar impact features.
The terrain for the scientific work conducted by ICESCAPE scientists on July 4, 2010, was Arctic sea ice and melt ponds in the Chukchi Sea. The five-week field mission was dedicated to sampling the physical, chemical and biological characteristics of the ocean and sea ice. Impacts of Climate change on the Eco-Systems and Chemistry of the Arctic Pacific Environment, or ICESCPE Mission, is a multi-year NASA shipborne project. The bulk of the research will take place in the Beaufort and Chukchi Seas in summer of 2010 and fall of 2011. Image Credit: NASA/Kathryn Hansen
West Antarctica's massive Pine Island Glacier is seen out the window of NASA's DC-8 research aircraft as it flies at an altitude of 1,500 feet, Tuesday, Oct. 27, 2009. This was the seventh science flight of NASA's Operation Ice Bridge, an airborne Earth science mission to study Antarctic ice sheets, sea ice and ice shelves. The glacier is one of the primary targets of the mission because of the rapid rate at which it is losing ice to the sea. Image Credit: NASA/Jane Peterson
On March 7, 1947, not long after the end of World War II and years before Sputnik ushered in the space age, a group of soldiers and scientists in the New Mexico desert saw something new and wonderful in these grainy black-and-white-photos -- the first pictures of Earth as seen from altitude greater than 100 miles in space. Just the year before in 1946, scientists like John T. Mengel, a NASA pioneer who later oversaw the Vanguard Program, began experimenting with captured German V-2 rockets. Mengel conducted upper atmosphere experiments by launchi
ng the rockets into near-earth orbit. He designed and fabricated the first research nose shell to replace of the V-2 warhead and began placing cameras in the nose shell. Before the Small Steps Program began in 1946 using V-2 rockets to take images from space, the highest pictures ever taken of the Earth's surface were from the Explorer II balloon, which ascended 13.7 miles in 1935, high enough to discern the curvature of the Earth. The V-2 cameras reached more than five times that altitude and clearly showed the planet set against the blackness of space. When the movie frames were stitched together, the panoramas taken in the late 1940s covered a million square miles or more at a single glance. Image Credit: Johns Hopkins Applied Physics Laboratory
On March 29, 2011, Operation IceBridge flew between deep canyons and over glaciers along the northwest coast of Greenland. IceBridge, now in its third year, makes annual campaigns in the Arctic and Antarctic where science flights monitor glaciers, ice sheets and sea ice. Image Credit: NASA/Michael Studinger
One of the fascinating aspects of viewing Earth at night is how well the lights show the distribution of people. In this view of Egypt, the population is shown to be almost completely concentrated along the Nile Valley, just a small percentage of the country’s land area. The Nile River and its delta look like a brilliant, long-stemmed flower in this photograph of the southeastern Mediterranean Sea, as seen from the International Space Station. The Cairo metropolitan area forms a particularly bright base of the flower. The smaller cities and towns within the Nile Delta tend to be hard to see amidst the dense agricultural vegetation during the day. However, these settled areas and the connecting roads between them become clearly visible at night. Likewise, urbanized regions and infrastructure along the Nile River becomes apparent. Scattered blue-grey clouds cover the Mediterranean Sea and the Sinai, while much of northeastern Africa is cloud-free. The thin yellow-brown band tracing the Earth’s curvature at the top of the image is airglow, a faint band of light emission that results from the interaction of atmospheric atoms and molecules with solar radiation at an altitude of approximately 60 miles (100 kilometers). This astronaut photograph was taken by the Expedition 25 crew on Oct. 28, 2010, with a Nikon D3S digital camera using a 16 mm lens. Image Credit: NASA
The Antarctic ozone hole reached its annual maximum on Sept. 12, 2008, stretching over 27 million square kilometers, or 10.5 million square miles. The area is calculated using data from the Ozone Monitoring Instrument on NASA's Aura satellite. This is considered a "moderately large" ozone hole, according to NASA atmospheric scientist, Paul Newman. And while this year«És ozone hole is the fifth largest on record, the amount of ozone depleting substances have decreased about 3.8% from peak levels in 2000. The largest ozone hole ever recorded occurred in 2006, at a s
ize of 10.6 million square miles. NASA has been monitoring the status of the ozone layer through satellite observations since the 1970s.