Mysterious rings in the Sahara Desert have a fiery origin

Today's Image of the Day from NASA Earth Observatory highlights a solitary mountain lifting out of the Sahara. In this extremely dry part of the desert, a set of dark massifs cuts across the wide expanse of light-colored sand. The difference in color and texture is so sharp that these outcrops seem almost like stranded islands. Isolated outcrops with their own history One of the most eye-catching formations is Jabal Arkanū in southeastern Libya, a circular mountain ringed by patterns that stand out...