Hubble Variable 1: The Star That Changed the Universe

Today we know that the Universe is filled with billions upon billions of galaxies, but in the early 1900s, it was widely accepted that the Milky Way was a single collection of stars with nothing beyond it. Andromeda, and other galaxies, were believed to just be ‘spiral nebulae’ lying within the Milky Way. However, there were telltale clues that astronomers could use to determine the distance between Andromeda and Earth, one of which is Cepheid variable stars. Stars of this type have very predictable patterns of brightness, which we can derive a light curve from -- thus making variable stars reliable distance markers.

This gave way to the discovery of many of the most fundamental concepts in modern astronomy.

Learn about how one star was able to revolutionize how we saw the universe, at
http://www.fromquarkstoquasars.com/hubble-variable-1-the-star-that-changed-the-universe/

Image Credit: S. Beckwith & the HUDF Working Group (STScI), HST, ESA, NASA