Astronomers observed a neutron star known as P13 suddenly brighten after years of inactivity. The decade-long study shows how changes in accretion can drive extreme X-ray power, offering new insight into ultraluminous X-ray sources and neutron star physics.Astronomers observed a neutron star known as P13 suddenly brighten after years of inactivity. The decade-long study shows how changes in accretion can drive extreme X-ray power, offering new insight into ultraluminous X-ray sources and neutron star physics.