Astronomy & Space Science · History of Astronomy
A topic within History of Astronomy, itself one of 8 topics in that field and part of Astronomy & Space Science.
2 works
Harlow Shapley & Heber D. Curtis
Sets out, in two independent essays published together, Shapley's case that spiral nebulae are minor features of one very large Milky Way against Curtis's case that they are separate galaxies at enormous distances, without resolving which is right.
link checked 17 Sept 2026Edwin Hubble
Identifies Cepheid variable stars in the Andromeda nebula and uses their period-luminosity relation to show it lies far beyond the Milky Way, settling the Shapley-Curtis debate in favour of separate galaxies.
link checked 17 Sept 2026