Earth's aerial glow lines the planet's horizon with the Moon in this image taken from the International Space Station on 14 November 2023, orbiting 260 miles (418 km) above the midwestern United States. The city lights of Denver and its suburbs glow in the lower right. The bright lights of Chicago are in the background.
Airglow is the emission of light by atoms and molecules in the upper atmosphere stimulated by sunlight to expel their excess energy. It is similar to auroras, but auroras are driven by high-energy particles from the solar wind while airglow is triggered by daily solar radiation. Studying airglow gives us an idea of the temperature, density and composition of the upper atmosphere, but it also helps us track how particles move through the region. Broad, high-altitude winds push their contents around the globe through the ionosphere, and the subtle dance of airglow follows their lead, emphasising global patterns.
A view of the Earth from the space station during orbital night. The Moon is above the Earth, almost exactly in the centre of the surface. An aerial glow outlines the atmosphere above the Earth's surface in a yellow shadow. Lights from cities decorate the Earth's surface, including an intensity of light near the horizon identifying the city of Chicago, and an intensity of light near the lower left identifying Denver.
Isn't it a beautiful picture?