100 years ago tonight, Edwin Hubble made the astronomical observation that definitively established the existence of the #universe beyond our own Milky Way galaxy. 

His discovery of a Cepheid variable #star in the Andromeda Galaxy — famously labeled "VAR!" with red ink in Hubble's own hand on the plate — demonstrated beyond a doubt that Andromeda was a separate #galaxy from our own.

Read more on the Carnegie Observatories site: https://obs.carnegiescience.edu/PAST/m31var

#Astronomy #History

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