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
Last Week *
HEA Dictionary * Archive
* Search HEAPOW
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.
Last modified June 2, 2000