Thanks to Astronaut Karen Nyberg I now know about this fascinating geological formation:
The "Eye of the Sahara" in Mauritania, Africa. August 28. pic.twitter.com/PMsRjtgtMv
— Karen L. Nyberg (@AstroKarenN) September 1, 2013
The Richat Structure is in Mauritania, surrounded by the Sahara. It’s pretty cool.