Ten thousand years ago, a star exploded. Now scientists are getting their best look ever at the details of that explosion, Cassiopeia A. Space-age tools and methods are allowing them to glimpse never-seen-before details that may change forever the way scientists think about star death, star formation and the distribution of matter in the galaxy. And now, a new image of that dead star has a starring role in First Lady Jill Biden’s digital Advent calendar this year.