Image: Earth in far-ultraviolet
On April 21, 1972, NASA astronaut John W. Young, commander of the Apollo 16 mission, took a far-ultraviolet photo of Earth with an ultraviolet camera. Young's 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.
Dr. George Carruthers, a scientist at the Naval Research Laboratory, developed the ultraviolet camera—the first moon-based observatory—for Apollo 16. Apollo 16 astronauts placed the observatory on the moon in April 1972, where it sits today on the moon's Descartes highland region, in the shadow of the lunar module Orion.
Provided by NASA