Explore This SectionScienceThe Solar SystemCassiopeia A Supernova RemnantSolar System ResourcesCurated Resource PackagesSolar System Home Cassiopeia A Supernova RemnantDecember 27, 2017 Cassiopeia A (Cas A) is the remnant of a massive star that exploded about 300 years ago. The X-ray image shows an expanding shell of hot gas produced by the explosion. Downloads Cassiopeia A Supernova Remnant Sep 4, 2023 JPEG (3.20 MB)
