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Crater Lakes

Credits
NASA Earth Observatory, Link: http://earthobservatory.nasa.gov/

Approximately 290 billion years ago, two big asteroids collided with the Earth. The craters are still visible - to astronauts in the orbit, the lakes inside the craters are popular subjects for photographs. The crater lakes' diameter is 26 resp. 36 kilometres.

 

Ouachita Mountains

Credits
NASA/GSFC (Jesse Allen, Robert Simmon); Link: http://earthobservatory.nasa.gov

The Ouachita Mountains in west central USA are more than 300 million years old. Today, they are weather-beaten and noticeably  eroded. The remains that you can see in this image were once a part of a much more extensive mountain range that is believed to have spanned from Texas to Southeast Canada. The image combined information from the wavelength ranges of infrared, red and green. The complex shape of the mountains is characterised by a pattern of longish, folded formations. Between the mountain slopes, you can see water, vegetation, cities and streets.

 

Oil Spill in the Gulf of Mexico

Credits
NASA/GSFC; Link: http://rapidfire.sci.gsfc.nasa.gov

On April 20, 2010 the oil drilling rig “Deepwater Horizon” leased by BP exploded in the Gulf of Mexico. This accident resulted in one of the most devastating natural disasters of our time: Over months, more than several hundred millions of litres of oil streamed into the sea. As the catastrophe unfolded, the oil also reached the Mississippi Delta. There is reason to believe that a part of the spill reached the world-spanning sea currents as well and thus has been spreading globally ever since.

The Growing City of Las Vegas

Credits
USGS; Link: http://earthexplorer.usgs.gov/

In comparing these two images, you get an idea of the rapid growth of Las Vegas, Nevada, between 1973 and 2002. Las Vegas is one of the fastest-growing US cities. Its high immigration rate and its areal extent have a negative effect on the water budget of this arid region. In order to solve this problem, politicians intervened: It is now forbidden to build new swimming pools, fountains must be operated using wastewater and the lawn can only be watered at certain days of the week.

 

Centre-Pivot Irrigation in Kansas

Credits
USGS; Link: http://earthexplorer.usgs.gov/

Approximately 80 per cent of the global water consumption can be ascribed to irrigation farming. In this false-colour image from above Kansas, red stands for healthy vegetation while farmland sticks out due to its conventional and circular irrigation. The so-called centre-pivot irrigation is common in dry areas with a large land-use management. Its characteristic shape is clearly visible from space.

 

Location: Kansas, USA
Picture taken on September 26, 2010
Sensor: Terra ASTER
Band combination: Vis/NIR

Grand Staircase-Escalante National Monument, Utah

Credits
NASA (Jesse Allen, Robert Simmon); Link: http://earthobservatory.nasa.gov

The geological history of the Grand Staircase-Escalante National Monument in Utah, USA, goes back more than 275 million years. This image shows a central part of the basin. The dendritic relief reveals a myriad of canyons. The erosions was caused by rivers millions of years ago. In the past, precipitation in this region was considerably heavier than it is today. Due to tectonic uplift, the area has dried out more and more.

 

Location: Utah, USA

Picture taken on May 15, 2005

Sensor: EO-1 - ALI

 

 

Sand Dunes, Idaho

Credits
NASA (Jesse Allen, Robert Simmon); Link: http://earthobservatory.nasa.gov

Along highway 20 from Idaho Falls heading toward Yellowstone National Park, green and golden fields dominate the fertile plain of the Snake River. The circular areas indicate extensively irrigated farmland. The white dunes developed towards the end of the last ice age approximately 10 000 years ago when the global climate started to become warmer and drier. Lakes and rivers dried up leaving fine sand behind. Continuous winds from the south west blew the sand in northeasterly direction, passing lava fields which are quite dark in the picture.

 

Glacier in Alaska

Credits
USGS; Link: http://www.usgs.gov

In the middle of this false-colour image, you can see the tongue of the Malaspina glacier. The glacier makes its way from the mountains in the north and is separated from the sea by its terminal moraine as can be seen in the lower part of the picture. Without the moraine or in the case of a sea-level rise, the glacier would come in contact with the warmer sea water and it would retreat more quickly than it does now. Satellite images and measurements on the ground show that most glaciers in Alaska are getting thinner and that only a few dozen are gaining in ice mass.

 

Hudson Bay, Canada

Credits
USGS; Link: http://earthexplorer.usgs.gov/

This image shows the two twin islands in the southern part of Hudson Bay (North and South Twin Island). In spring, the ice of Hudson Bay clears, usually leaving the south-western part, in which the two islands are located, as the last area with a closed ice sheet. Climatologists are worried about Arctic melting processes: In recent years, there have been more and more ice-free phases, signalling an increase in climate warming.

 

Location: Hudson Bay, Canada
Picture taken on February 20, 2002
Sensor: Landsat ETM+
Band combination: MIR/NIR