Waves in the Sky

What is the wave-like structure besides the Milky Way in this photograph made from a remote location in northern Chile? It is similar to airglow but in a wave-like structure. Viewing the sky from very high altitude locations is an amazing experience. Stars become sharp and dazzling with less atmospheric turbulence and extinction affected on their light. Located in Lauca National Park at Chile’s far north on the border with Bolivia, volcanoes Pomerape (6282 m) and Parinacota (6332 m) are captured under the Milky Way from a 5000m high location in the Chilean Andes. The photo is made with a single 20-second exposure using a DSLR camera (at high ISO) and 35mm lens.