Wikipedia:Today's second feature/December 24, 2005
Today's featured picture
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SN 1572, or Tycho's Nova, was a supernova in the constellation Cassiopeia, one of the few supernovae visible by the naked eye. It was first observed on November 11 1572 by Tycho Brahe, when it was brighter than Venus.
This is a false-colour x-ray image from the Chandra X-ray Observatory in which the energy levels of the x-rays have been assigned red, green and blue colors in three bands from 0.95 keV to 6.1 keV. The red and green bands highlight the expanding cloud of plasma with temperatures in the millions of degrees. The blue band shows a surrounding shell of extremely high energy electrons.