An astronaut on board the International Space Station took a photo of Mount Arkanu, a massif of concentric rocky rings in the Sahara. The structure, which is over 15 miles wide and is home to ancient artworks and herds of cattle, stands up to 2,600 feet above the surrounding sands and stretches up to 15.5 miles across at its widest point. Scientists previously assumed that the massif was an ancient impact crater that formed when a giant space rock slammed into the northeast Sahara. However, new research has revealed that the mountains were created when magma rose toward the surface and intruded into the surrounding rock hundreds of millions of years ago. The massif has two large gaps in its outermost southern wall that have been slowly carved out by ghost rivers, which occasionally fill with water when it rains.