Ejnar Hertzsprung

person · earth

Danish chemical engineer turned astronomer who, working at Leiden, plotted stellar luminosity against colour around 1911 and identified two distinct populations he named giants and dwarfs - the first demonstration that stars of the same surface temperature can differ enormously in size and luminosity. That distinction is the seed of the whole evolutionary picture: it implies that a star's observable properties change over its life rather than being fixed at birth. His work was published in a form and venue that attracted less immediate attention than Russell's, which is part of why the diagram's name took decades to settle into the right order. Not a place.

A person is not a place. Drawing it on a map would assert something about the world that no stored fact supports.