Deserts are known for being desolate and lifeless, but they are also quite striking and beautiful, especially when seen from above. Different types of sand, topography, wind and climate combine to form a tremendous variety of landscapes. Shifting dunes are carved into an endless number of constantly changing shapes.

The images in this gallery, taken by orbiting astronauts and satellites, show some of the most beautiful, most haunting, biggest, rarest and most stunning desert vistas on Earth.

Algeria's Sand Sea

The Issaouane Erg covers almost 15,000 square miles in eastern Algeria. This sea of sand in the central Sahara desert has three different scales of dunes. Mega-dunes, also known as draas or whalebacks, form over hundreds of thousands of years and can be several hundred miles long. Mesoscale dunes form on top of the mega-dunes, and move on decade time scales. Smaller dunes form on and around the larger dunes. They are sculpted into different shapes by the wind, and are constantly shifting.

In the image above, captured by astronauts on the International Space Station in 2005, mesoscale dunes have been shaped into star dunes that look a bit like starfish and crescent dunes. In the image below, taken by astronauts on the ISS in 2006, the large, rolling shapes are mega-dunes. The smallest dunes show up as wrinkles alongside larger dunes.

Click on any of the gallery images for high-resolution versions.

Images: NASA

Caifornia's Imperial Dunes

The Algodones Dunefield, located where Arizona and California meet Mexico, is around 6 miles wide and stretches for 45 miles. The dunes may be most famous for their role as part of the planet Tatooine from Star Wars. The dunes are an official National Recreation Area managed by the Bureau of Land Management. The only artificial structure in the dunes is the All American Canal that can be seen cutting across the dunes near where they run up against agricultural fields in Mexico on the right end of the photo. This image was taken by astronauts aboard the International Space Station in 2005.

Image: NASA

New Mexico's White Sands

The sand that makes up the dunes in White Sands National Monument are made of gypsum, an evaporite mineral left behind when bodies of water dry up. In this case an ancient shallow sea dried up a couple of hundred million years ago, and then a large lake evaporated several thousand years ago. Because gypsum is easily dissolved by water and moved by rivers, these dunes are quite rare. They exist here because there is no outlet from the basin where they lay, so rivers entering the area dry up instead of carrying the gypsum away.

The dunefield covers 275 square miles in southern New Mexico. Almost half of the area is protected as White Sands National monument. This image of the area was captured by the Advanced Land Imager onboard NASA’s Earth Observing-1 satellite on June 27.

Image: NASA

Saudi Arabia's Empty Quarter

This aptly named stretch of desert is the world's largest sand sea, covering 225,000 square miles. The area shown above is in Saudi Arabia, but the sea flows into parts of Yemen, Oman and the United Arab Emirates as well.

The grey and white areas between the pink sand dunes are dry salt flats. Temperatures in the Empty Quarter, which is the English translation of the Arabic name Rub’ al Khali, can top 130 degrees Fahrenheit, making the area inhospitable to almost everything except a few plants, spiders and rodents. The sand covers one of the most prolific oil producing areas in the world.

This image was captured in 2001 by the Enhanced Thematic Mapper on the NASA/USGS Landsat 7 satellite. See a closer view of the dunes below. Learn more about the Empty Quarter in this National Geographic video.

Images: NASA/USGS

Algeria's Tifernine Dune Field

This part of the Sahara Desert, located in eastern Algeria, abuts the dark grayish-brown Tinrhert Plateau. Winds have sculpted star dunes on top of older, larger dunes and evaporite minerals, including salt, have collected in small white depressions among the dunes. Today, the climate is arid and hot, but the river-carved valleys on the edge of the plateau give evidence of wetter times in the past.

This image was taken by astronauts aboard the International Space Station in August 2008.

Image: NASA

Ounianga Lakes, Chad

These finger lakes are the remnants of a single larger lake that began shrinking around 5,500 years ago. Sand was blown in by the wind partially filling in the basin and breaking up the remaining water into separate lakes. Nine of the 10 lakes are freshwater, fed by an underwater aquifer. Ancient pollen found in the sediment in the lakes has shown that the area was once mildly tropical.

This image was taken by astronauts on the International Space Station on Nov. 14.

Image: NASA

The World's Tallest, Oldest Dunes

The Namib Desert features dunes that reach nearly 1,000 feet high, carved by winds along Namibia's Atlantic coast. The Namib-Naukluft National Park pictured here is Africa's largest game park and home to hyenas, jackals, geckos and other strange animals. The desert may also be the world's oldest, having been in a dry climate for 55 million years. Today, the area receives an annual average of just 2.5 inches of rain.

The image above was captured in 2000 by the Landsat-7 satellite, run by NASA and the U.S.Geological Survey. The topographic image below was made by combining a 2002 image with topographical data, both aquired by the ASTER instrument on NASA's Terra satellite, which celebrates its 10th anniversary this year.

Images: Above: NASA/USGS. Below: NASA/ASTER

Colorado's Great Sand Dunes

This collection of dunes nestled up against the Sangre de Cristo Mountains in southern Colorado was designated a national monument in 1932 and a national park in 2004 and today are visited by around 300,000 people each year. Though they cover just 30 square miles, the dunes reach up to 750 feet high and are the tallest sand dunes in the United States.

The light-colored sand that makes up the dunes is sediment eroded from the adjacent mountains and then deposited in a lake that repeatedly dried up over time, exposing the lakebed to the wind.

The image of Great Sand Dunes National Park above was captured by the Ikonos sensor aboard the GeoEye satellite in 2005. Below is a photograph taken by astronauts aboard the International Space Station in 2007.

Images: Above: GeoEye. Below: NASA.

Suctoria: Ciliates Who Lost Their Cilia

Smooth, nearly sandless, flat-bottomed basins laced with large dunes coated by smaller, scalloped dunes give this stretch of the central Sahara a honeycomb look. The Murzuq Sand Sea in Libya features vast swaths of these bigger dunes, known as draas. The smaller dunes, which can be seen in greater detail in the close-up below, include many star dunes as well as fairly linear longitudinal dunes and curved transverse dunes. The upwind side of the smaller dunes are smoother and steeper than the downwind, or lee, side. This photograph was taken from the International Space Station by astronauts in December 2008.

Images: NASA

Australia's Lake Eyre

Heavy rains earlier this year began refilling this large dry lake bed in this part of the Simpson Desert in South Australia. Water can be seen flowing into the lake bed in the image above, captured May 9 by the Landsat-5 satellite. Along with the water came plants and thousands of birds. The photo below, taken by the satellite on Feb. 18 shows how dry the area usually is.

Images: NASA/USGS The Sahara's Outcrops

Rivers of sand coated in dunes sweep around hard rock outcrops in this very arid, barren stretch of the Sahara in Libya. This image was captured by NASA's Terra satellite in 2002.

Image: NASA/ASTER

Australia's Scars

This part of the Simpson Desert in Australia's Northern Territory has been largely covered in desert scrub, turning it green and keeping the wind from shifting the dunes. But a fire here, maybe a year before this picture was taken in 2002, burned the vegetation, revealing the sand beneath it.

The strange pattern in the sand was probably caused by a 90-degree shift in wind direction while the land was burning. This photo was captured by astronauts aboard the International Space Station.

Image: NASA

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