supernova-remnants

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.

Nebulae are vast clouds of gas and dust between stars. Some are stellar nurseries where new stars form, some are shells shed by dying stars, and some are the debris of supernova explosions. The Orion Nebula is a nursery visible to the naked eye; the Crab Nebula is the expanding wreckage of a star that exploded in 1054.