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This is a radio image of Cassiopeia A, a young supernova remnant nearby in our Galaxy, composited with a photograph of the NRAO Very Large Array telescope at dusk. Cassiopeia A is the brightest radio source in the sky except the Sun. It is about 10 light years across and about 10,000 light years away.
It is the remnant of a supernova explosion that occurred approximately 300 years ago.Image credit: Image courtesy of NRAO and Michael Bietenholz, York University (data courtesy of NRAO and R. Perley)
