The last time someone photographed the exosphere, the outermost layer of Earth’s atmosphere separating it from outer space, was in the 1970s from the surface of the Moon.
This is a problem for two reasons, said Brian Walsh,…

The last time someone photographed the exosphere, the outermost layer of Earth’s atmosphere separating it from outer space, was in the 1970s from the surface of the Moon.
This is a problem for two reasons, said Brian Walsh,…