High above Earth, an astronaut looked down on northern Ethiopia. Below, Lake Tana, about 1,200 square miles across, held two dark islands whose monasteries guard the mummified remains of ancient emperors.
In the image, the lake glows an unhealthy…

High above Earth, an astronaut looked down on northern Ethiopia. Below, Lake Tana, about 1,200 square miles across, held two dark islands whose monasteries guard the mummified remains of ancient emperors.
In the image, the lake glows an unhealthy…