Northern sky, from Cassiopeia to Ursa Minor and Polaris, as seen above prehistoric rock art in the remote valley of Teimareh in central Iran. The valley is full of ancient petroglyphs, dating back to 4500 to 17000 years ago. With about 20,000 engraved images, the region is one of the world's most diverse petroglyph sites, still largely undiscovered. Here in the foreground two horse riders and the crescent Moon are pictured.