Far-UV photo of Earth
On 21 April 1972, NASA’s Apollo 16 mission took a far-ultraviolet photo of Earth with an ultraviolet camera. The original black-and-white picture was printed on Agfacontour professional film three times, with each exposure recording only one light level. The three light levels were then colored blue (dimmest), green (next brightest) and red (brightest), resulting in the enhanced-color image seen here.
—Apollo 16 Far UV Camera, G. Carruthers, NASA