Two lectures, one afternoon, the size of the sky

Harlow Shapley, thirty-four, from Mount Wilson, has used globular clusters and Cepheids to put the Sun far from the centre of a vast Milky Way. He thinks that Milky Way is essentially the universe. Heber Curtis, of Lick, argues that the spiral nebulae are other galaxies, island universes, and that our system is smaller than Shapley wants.

They lecture. They do not hug and switch sides. The audience does not vote the cosmos into being. The argument is the event.

Andromeda’s distance will wait for Hubble’s Cepheids. Shapley’s direction for the Sun in the Galaxy will stand. Curtis’s island universes will stand. A debate can be historically famous and still unfinished on the day it is held.