Cassiopeia A in 60 Seconds
Narrator (April Hobart, CXC): Over three hundred years ago, a very large star ran out of fuel and collapsed. This event created an explosion, known as a supernova, which then produced an expanding field of debris. This debris field is what we now call the Cassiopeia A supernova remnant. Astronomers studying this supernova remnant have found something very interesting. They determined that some of the inner layers of the star before the supernova explosion are now found on the outer edges of the supernova remnant. In other words, it appears that the star has turned itself out, so to speak, at the end of its life. Supernovas and the remnants they create spread elements like carbon, oxygen, and iron into the next generation of stars and planets. Therefore, understanding exactly how these stars explode is very important for knowing how the Universe has gotten to where it is today.