Credit: MPE

Mirror in the Sky

In the early days of X-ray astronomy, it was thought that occultations by the moon could be used to determine locations of X-ray sources in the sky. However, it was not until 28 years after the birth of X-ray astronomy that an X-ray image of the moon itself was actually obtained. This image, shown above, was obtained in 1990 by the ROSAT PSPC. The X-ray bright side of the moon is due to reflection of the sun's X-rays to the earth, just as a half moon reflects the sun's visible radiation. The part of the moon facing away from the sun is dark in X-rays, just as it is in optical light. This observation was the first to show that all the diffuse X-ray background comes from distances farther than the moon's orbit.

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Each week the HEASARC brings you new, exciting and beautiful images from X-ray and Gamma ray astronomy. Check back each week and be sure to check out the HEAPOW archive!

Page Author: Dr. Michael F. Corcoran
Last modified June 2, 2000