In 1920, astronomers Harlow Shapley and Heber Curtis held a Great Debate. Shapley argued that the spiral nebulae were small ...

Edwin Hubble was young and ambitious ... His measurements marked the end of the Great Debate about the Milky Way’s size and the nature of the nebulae. Hubble wrote about his discovery to Harlow ...

Edwin Hubble was young and ambitious ... His measurements marked the end of the Great Debate about the Milky Way's size and the nature of the nebulae. Hubble wrote about his discovery to Harlow ...

Edwin Hubble uses the telescope at the Mount Wilson ... His measurements marked the end of the Great Debate about the Milky Way's size and the nature of the nebulae. Hubble wrote about his ...

Hubble makes his mark Edwin Hubble was young and ambitious ... His measurements marked the end of the Great Debate about the Milky Way’s size and the nature of the nebulae.

Edwin Hubble seated at the 2.5-metre reflecting ... While Andromeda, the closest galaxy to our Milky Way, is moving toward us, further measurements of other galaxies by Hubble and Belgian ...