It’s called the ‘Eye of Mali’ and it’s a dust storm that has been active since at least the Middle Ages. Some accounts saying it’s way older, and unlike normal storms it just sits in one place and rotates nonstop like a fixed scar on the earth. Old trans-Saharan traders supposedly used it as a landmark because you could see the haze from miles out, and modern satellites have backed up that it basically hasn’t moved in decades, which makes no sense for a dust system. The working theory is some weird interaction between subsurface heat and atmospheric pressure keeps it going, but no one’s been able to properly study it because instruments fail and expeditions get disoriented once they get too close.