X-Raying the Moon . ... Credit Copyright: DARA, ESA , NASA , Max Planck Institut , J.H.M.M. Schmitt Explanation: Above is a picture of the Moon taken in X-rays by the Roentgen Observatory Satellite ROSAT in 1990. This famous picture 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 lunar crescent shines because it reflects X-rays emitted by the Sun . ... NASA Web Site Statements, Warnings, and Disclaimers . ...