Quick factsWhat it is: Pa 30, a supernova remnantWhere it is: 7,500 light-years away, in the constellation CassiopeiaWhen it was shared: Oct. 6, 2026A mysterious "guest star" recorded by medieval astronomers nearly 850 years ago has revealed new secrets after scientists obtained the clearest images yet of its explosive aftermath. New observations of Pa 30, thought to be the leftovers of a historic supernova called SN 1181, show that its spectacular firework-like filaments are not smooth streams of material. Instead, they consist of chains of tiny gas knots.SN 1181 is so called because astronomers in China and Japan recorded its brief appearance in the year 1181, when they saw it as a naked-e...