Historical event · 1920 CE
The Great Debate
History of Astronomy
What happened
In 1920 Harlow Shapley and Heber Curtis debated the scale of the universe: whether the spiral nebulae lie within the Milky Way or are separate 'island universes'. Edwin Hubble settled the question a few years later by measuring the distance to Andromeda.
Connections
Knowledge connections
- Part ofModern Astronomy
- Related toAndromeda Galaxy
- Related toThe Milky Way
Sources & references
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.
- BritannicaEncyclopaedia Britannica
General reference for the history of astronomy, biographies, and cultural context.