December 13

Heinrich Heine, poet and essayist born into a Jewish family in Dusseldorf, entered the world in the Duchy of Berg.

The Council of Trent convened in northern Italy, beginning the deliberations that shaped Catholic doctrine and reform for centuries.

Using an interferometer mounted on the Mount Wilson telescope, Albert Michelson and Francis Pease measured the angular size of Betelgeuse, the first diameter determined for any star beyond the Sun.