NASA shared an eerie image of what was once a lake larger than the Caspian Sea in central Africa. Called Mega Chad, this massive body of water stretched 150,000 square miles across the Sahara and would have been the largest on Earth today. Modern Lake Chad is just a fraction of its former size and sits inside the ancient body of water's shoreline that is still etched into the desert landscape. The image highlights the dark lower-elevations of the area, along with sand spits and beach ridges that formed along Lake Mega Chad's northeastern shores. NASA shared an eerie image of what was once a lake larger than the Caspian Sea in central Africa.