The X-Ray Moon . ... DARA, ESA , MPE , NASA , J.H.M.M. Schmitt Explanation: This X-Ray image of the Moon was made by the orbiting Roentgen Observatory Satellite ( ROSAT ) in 1990. It shows three distinct regions: a bright X-ray sky, a bright part of the Moon, and a relatively dark part of the Moon. The bright X-ray sky is due to the diffuse cosmic X-ray background . The bright lunar crescent shines because it reflects X-rays emitted by the Sun . ... Where do those X-rays from? ...