Researched
Other Galaxies (Hubble)
Edwin Hubble finds Cepheid stars in the Andromeda nebula in 1923-24 and shows it lies far outside the Milky Way: the universe holds many galaxies.
Open in the interactive tree →Using the 100-inch Hooker telescope at Mount Wilson and Leavitt's period-luminosity law, Hubble ended the 'Great Debate' about the size of the universe. His next step was the expansion of the universe in 1929.
Prerequisites
Unlocks
- Expansion & Big Bang1929Hubble's galaxy distances led to the expanding universe