This image from NASA's Spitzer Space Telescope shows the scattered remains
of an exploded star named Cassiopeia A. Spitzer's infrared detectors
"picked" through these remains and found that much of the star's original
layering had been preserved.
In this false-color image, the faint, blue glow surrounding the dead star
is material that was energized by a shock wave, called the forward shock,
which was created when the star blew up. The forward shock is now located
at the outer edge of the blue glow. Stars are also seen in blue. Green,
yellow and red primarily represent material that was ejected in the
explosion and heated by a slower shock wave, called the reverse shock
wave.
The picture was taken by Spitzer's infrared array camera and is a
composite of 3.6-micron light (blue); 4.5-micron light (green); and
8.0-micron light (red).
