Original sentence: Cepheid variables are also used to determine the Sun's height above the Galactic plane, to establish the distance to Galactic Center, and to interpret local spiral structure in the vacinity surrounding the Sun.Edwin Hubble would discover Cepheid variables in M31 and settle the Island Universe debate, which centered around the mystery of whether our Galaxy and the universe were synonmous, or was the Milky Way merely one in a plethora of galaxies that constitutes the universe
Edited sentence: Cepheid variables are also used to determine the Sun's height above the Galactic plane, to establish the distance to Galactic Center, and to interpret local spiral structure in the vicinity surrounding the Sun.Edwin Hubble would discover Cepheid variables in M31 and settle the Island Universe debate, which centered around the mystery of whether our Galaxy and the universe were synonymous, or was the Milky Way merely one in a plethora of galaxies that constitutes the universe