Mountain Shadows, Western Mongolia


An astronaut aboard the International Space Station (ISS) took this photograph of a mountain range in the Altai Mountains from Central Asia. Most daytime, nadir (straight down) views of Earth from the ISS appear two-dimensional. Therefore, astronauts often take pictures when the angles of the Sun are low in order to reveal the three dimensions of the landscape.

In this photo, late afternoon sunlight casts long shadows on the surrounding snowy plains in Mongolia. The shadows cast the general shapes of the mountains, their heights relative to each other, and some details of the crests of the ridges. Several peaks in this range rise to elevations greater than 3,000 meters (10,000 ft) above sea level; they stand about 1,700 meters (5,600 ft) above the plains.

The flat plains were formed by sediment carried by rivers flowing out of the mountains; these are known as alluvial fans. The water from these rivers eventually flows into Uvs Lake (just outside the right margin of the image), saline solution, endorheic lake in this semi-arid region.

As is common in dry places around the world, water from mountain rivers mostly flows underground through alluvial fans (except after heavier rains, when water flows over fan surfaces). Where the water again reaches the surface, it forms a line of springs visible from space. This water gives rise to darker patches of vegetation and snowmelt.

This spring water also supplies the local populations. One of the darkest spots along the Spring Line is the city of Ulaangom (pop. 31,000), the capital of Uvs Province in Mongolia. The village of Turgan also appears as a small gray speck next to a river.

Other faint features on the plains show the work of humans. A road and the new Ulaangom airport appear as straight lines. For an idea of ​​scale, the distance from the center of Ulaangom to the airport is 12.5 kilometers (8 miles).

Astronaut Photography ISS066-E-137473 was acquired on February 7, 2022, with a Nikon D5 digital camera using a 200 millimeter focal length. It is provided by the ISS Crew Earth Observation Facility and the Earth Science and Remote Sensing Unit at Johnson Space Center. The image was taken by a member of the Expedition 66 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory in the context of ISS National Laboratory to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make these images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at NASA/JSC Gateway to Astronaut Photography of Earth. Caption by Justin Wilkinson, Texas State University, JETS contract at NASA-JSC.


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