Brief Time-lapse Movie of Cassiopeia A
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This brief movie of X-ray data from Chandra of Cas A was
made by combining observations taken in January 2000, February 2002, February 2004, and
December 2007. In these images, the lowest-energy X-rays Chandra detects are shown in red,
intermediate energies in green, and the highest energies in blue. Scientists have used the movie to
measure the expansion velocity of the leading edge of the explosion's outer blast wave (shown in
blue). The researchers find that the velocity is 11 million miles per hour, which is significantly slower
than expected for an explosion with the energy estimated to have been released in Cas A.
[Runtime: 00:20]
(Credit: NASA/CXC/SAO/D.Patnaude et al.)