Space
Cassiopeia A: The Youngest Supernova Remnant in the Milky Way
Cassiopeia A is the expanding debris field of a star that exploded around 1680 CE — yet almost no one on Earth recorded it. Today, X-ray and infrared telescopes reveal a forensic masterpiece: shock waves, newly minted heavy elements still glowing from the blast, and a neutron star cooling at the center. Cas A is not just a beautiful object. It is the best laboratory we have for understanding what supernovae actually do to the universe.