This image was taken by an astronaut looking south-east across the <a href="//commons.wikimedia.org/wiki/South_America" class="mw-redirect" title="South America">South American</a> continent when the <a href="//commons.wikimedia.org/wiki/International_Space_Station" title="International Space Station">International Space Station</a> (ISS) was almost directly over the <a href="//commons.wikimedia.org/wiki/Category:Atacama_Desert" title="Category:Atacama Desert">Atacama Desert</a> near <a href="//commons.wikimedia.org/wiki/Chile" title="Chile">Chile’s</a> <a href="//commons.wikimedia.org/wiki/Pacific_Ocean" title="Pacific Ocean">Pacific</a> coast. The high plains (3000–5000 meters) of the Andes Mountains, also known as the Puna, appear in the foreground, with a line of young <a href="//commons.wikimedia.org/wiki/Volcano" title="Volcano">volcanoes</a> facing the much lower Atacama Desert (1000–2000 m elevation). Several <a href="//commons.wikimedia.org/wiki/Salt" title="Salt">salt</a>-crusted dry <a href="//commons.wikimedia.org/wiki/Lake" title="Lake">lakes</a> (known as salars in Spanish) occupy the basins between major thrust faults in the Puna. Salar de Arizaro (foreground) is the largest of the dry lakes in this view. The <a href="//commons.wikimedia.org/wiki/Atlantic_Ocean" title="Atlantic Ocean">Atlantic Ocean</a> coastline, where <a href="//commons.wikimedia.org/wiki/Argentina" title="Argentina">Argentina’s</a> capital city of <a href="//commons.wikimedia.org/wiki/Buenos_Aires" title="Buenos Aires">Buenos Aires</a> sits along the <a href="//commons.wikimedia.org/wiki/R%C3%ADo_de_la_Plata" title="Río de la Plata">Río de la Plata</a>, is dimly visible at image top left. Near image centre, the transition between two distinct geological zones, the Puna and the Sierras Pampeanas, creates a striking landscape <a href="//commons.wikimedia.org/wiki/Category:Contrast" class="mw-disambig" title="Category:Contrast">contrast</a>. Compared to the Puna, the Sierras Pampeanas <a href="//commons.wikimedia.org/wiki/Mountains" title="Mountains">mountains</a> are lower in elevation and have fewer young volcanoes. Sharp-crested ridges are separated by wide, low <a href="//commons.wikimedia.org/wiki/Valley" title="Valley">valleys</a> in this region. The <a href="//commons.wikimedia.org/wiki/Category:Salinas_Grandes" title="Category:Salinas Grandes">Salinas Grandes</a>—ephemeral shallow salt lakes—occupies one of these valleys. The general colour change from <a href="//commons.wikimedia.org/wiki/Category:Red" title="Category:Red">reds</a> and <a href="//commons.wikimedia.org/wiki/Category:Brown" title="Category:Brown">browns</a> in the foreground to <a href="//commons.wikimedia.org/wiki/Blue" title="Blue">blues</a> and <a href="//commons.wikimedia.org/wiki/Green" title="Green">greens</a> in the upper part of the image reflects the major climatic regions: the deserts of the Atacama and Puna versus the <a href="//commons.wikimedia.org/wiki/Category:Grass" title="Category:Grass">grassy</a> plains of central Argentina, where <a href="//commons.wikimedia.org/wiki/Rain" title="Rain">rainfall</a> is sufficient to promote lush prairie grass, known locally as the pampas. The Salinas Grandes mark an intermediate, semiarid region.
The NASA Expedition 23 crew
2010-05-17
<a rel="nofollow" class="external text" href="http://earthobservatory.nasa.gov/IOTD/view.php?id=43961">NASA Earth Observatory</a>