|NASA Photo ID||ISS063-E-81395|
|Time taken||21:10:15 GMT|
|Nikon D5 Electronic Still Camera|
|5568E: 5568 x 3712 pixel CMOS sensor, 35.9 x 23.9 mm, total pixels: 21.33 million, Nikon FX format|
|720 pixels||480 pixels||Yes||No||Download Image|
|5568 pixels||3712 pixels||No||No||Download Image|
|640 pixels||427 pixels||No||No||Download Image|
A sharp contrast in nighttime light density distinguishes the sparsely populated Tibetan Plateau-the "Roof of the World"-from the fertile and densely inhabited Indo-Gangetic plain of Northern India and Pakistan. These regions are not only visually distinct from an astronaut's view; they are physically separated by the Himalayan mountain range. The geography and population dynamics in this region are one legacy of the ongoing orogeny, or collision, of the Indian and Eurasian tectonic plates.
South of the Himalayas, the cities of New Delhi, India, and Lahore, Pakistan, stand out among the network of cities on the plain. This region-enriched with alluvial deposits that are delivered by the Indus and the Ganges rivers-is agriculturally fertile and has long been home to highly-concentrated human settlements. Today, it is home to more than 400 million people and one of the most densely populated regions on Earth. For astronauts, this is also one of the few areas where geopolitical boundaries come to life at night, as orange security lights make clear the international border between India and Pakistan.
On the other side of the Himalayas, tectonic forces have worked for about 50 million years to elevate the Tibetan plateau to an average of 4500 meters (14,764 feet) above sea level. The plateau is home to numerous glaciers that collectively add up to the third largest ice mass on Earth (after the polar ice sheets). Unlike the plain to the south of the Himalayas, the high-altitude conditions and harsh climate on the plateau are not conducive to extensive agriculture or human settlements. The people who do inhabit the plateau primarily practice pastoral nomadism or grow cold-adaptive crops like barley.