↬ Brain Pickings
I particularly liked her efficient explanation of 'standard candles', which is something I've tried to put as simply and plainly as possible, when I describe the importance of Henrietta Swan Leavitt's discovery of the relationship between luminosity, or brightness, of a certain type of star, the Cepheid variable stars. Thanks to her discovery, we now know there is a simple relationship between period and luminosity for these stars - something which radically changed the theory of modern astronomy, an accomplishment for which she received almost no recognition during her lifetime.
Cepheid variables are a class of pulsating star. They are named for the star Delta Cephei in the Cepheus constellation. The relationship between a Cepheid variable's luminosity and pulsation period is quite precise, securing Cepheids as viable standard candles and the foundation of the Extragalactic Distance Scale.
My portrait of Swan Leavitt, shows Henrietta, related constellations, and a plot of her period-luminosity relation. This is a first edition lino block print in lavender-silver and gold ink on Japanese kozo paper (10" by 12.5" or 25.4 cm by 31.8 cm). The first edition is a run of 6 prints.