Del

Its story

Delta Cephei gave its name to an entire class of stars: the Cepheids, pulsating beacons that astronomers like Henrietta Leavitt used to measure distances to whole galaxies. At some 865 light-years, this yellow supergiant beats with almost metronomic regularity every five days and nine hours, swelling and contracting as its brightness rises and falls. Few stars have taught us so much about the scale of the universe.