Hello! I'm starting this book type I keep seeing where people update their books daily. Its fact time!
The cover of this book is a picture of Cassiopeia A, a supernova remnant. It is 3,400 parsecs, or 10,200 light years away. It has a diameter of 3.3 parsecs, or 9.9 light years. It is a pulsar wind nebula, also known as a supernova remnant or SNR. Some time ago, a large star exploded in a supernova and shot all of this stuff in every direction, leaving this behind. It is not listed in NGC or Messier, groups that list deep sky objects or DSOs. Cassiopeia A was discovered in 1948 by Martin Ryle and Francis Graham, astronomers at Cambridge.
