Portal:Astronomy/Picture/6

From Wikipedia, the free encyclopedia
Credit: NASA/JPL-Caltech

Cassiopeia A (Cas A) is a supernova remnant in the constellation Cassiopeia and the brightest extrasolar radio source in the sky at frequencies above 1 GHz. The supernova occurred approximately 11,000 light-years (3.4 kpc) away in the Milky Way.