In 1572, astronomer Tycho Brahe witnessed the supernova that created the stellar remnant Cassiopeia A. All that remains from this powerful explosion is a cloud of debris expanding away from a neutron star. New images from NASA's Spitzer space telescope show that this neutron star isn't out of action yet, though, in fact, it might have fired out a blast of energy 50 years ago, which is now lighting up the surrounding material. This recent activity might mean that the neutron star is actually an exotic magnetar, which regularly release bursts of gamma rays.