Where on earth is this?

Kalahari desert, Namibia - one of 30 abstract images chosen from the 400,000 images taken by the Landsat 7 satellite, and displayed at the Library of Congress in 2000. The website is a bit slow to load, but worth visiting.

update (2016) - that website seems to have disappeared, but the "earth as art" exhibitions have been held several times. Try this one instead, from 2005, or this more recent one.