When a star that has more than about eight times the mass of the Sun dies, it either collapses to a black hole or explodes as a supernova1. In the latter case, a blast at the centre of the star —usually caused by the formation of a stellar remnant called a neutron star — ejects the surrounding material at high speed. The expansion of this material releases trapped energy, providing a nearly constant luminosity (equivalent to that of about 100 million Suns) for roughly 100 days, before fading. Supernovae lasting more than 130 days are extremely rare2. On page 210, Arcavi et al.3 report that a supernova known as iPTF14hls glowed brilliantly for more than 600 days, making it the longest-lived bright supernova ever observed.