How far away are galaxies?
•
1755
Kant ® island universes
1845
•Earl of Rosse®spiral
M51
•BUT Herschel ® planetary nebula
in Draco
•
1920
•Shapley-Curtis debate
1924
•Hubble ®
Cepheid in Andromeda galaxy
•Andromeda:
distance = 750 kpc, diameter = 70 kpc
•
M51, Whirlpool galaxy
NGC 5194
NGC 5195