evidence: An astronaut aboard the International Space Station captured this image of the Siachen Glacier on the spine of the Karakoram mountains in central Asia. This remote part of the world—where territories of Pakistan, India, and China all meet—is uninhabited and lies well above the tree line. Siachen is the second-longest glacier within Earth’s midlatitudes, which exclude, for example, the continental glaciers of Antarctica and Greenland. It measures 75 kilometers (47 miles) long and is 3.5 kilometers (2.2 miles) wide at the top-center of this image. The image shows four smaller tributary glaciers flowing into the main Siachen Glacier. The many dark, parallel lines in the glacier and its tributaries are moraines, which give a sense of the southward flow of the glacier. The darkest and most prominent moraine results from the merging of moraines from the Teram Shehr Glacier and its neighbor immediately to the north. Early afternoon sunlight casts shadows from small cumulus clouds onto the glaciers’ surfaces.