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Cassiopeia A is the remnant of a supernova explosion that occured over 300 years ago in our Galaxy, at a distance of about 11,000 light years from us. Its name is derived from the constellation in which it is seen: Cassiopeia, the Queen. A supernova is the explosion that occurs at the end of a massive star's life; and Cassiopeia A is the expanding shell of material that remains from such an explosion.
This radio image of Cassiopeia A was created with the National Science Foundation's Very Large Array telescope in New Mexico. The image was made at three different frequencies: 1.4 GHz (L band), 5.0 GHz (C band) and 8.4 GHz (X band). Cassiopeia A is one of the brightest radio sources in the sky and has been a popular target of study for radio astronomers for decades. The material that was ejected from the supernova explosion can be seen in this image as bright filaments.Image credit: L. Rudnick, T. Delaney, J. Keohane, B. Koralesky and T. Rector; NRAO/AUI/NSF
