The atmospheric nightglow is observed on Earth. On Mars, it was something expected, yet never observed in visible light until now. This image shows an artist’s impression of what nightglow might look like to an astronaut in the polar winter regions of Mars at night. Image credit: NASA / JPL-Caltech /Cornell University / Arizona State University / E.W. Knutsen. Airglow occurs when two oxygen atoms combine to form an oxygen molecule, about 50 km above...
