On this day in 1924, Edwin Hubble published his discovery that Andromeda was actually another galaxy, not a nebula. It was published in the New York Times. Hubble also announced that the Milky Way is only one of many galaxies in the universe. He disclosed that Andromeda is not a cloud of material lurking in our galaxy, rather it is a separate galaxy, a vast swirl of stars at tremendous distance. Hubble calculated that Andromeda was approximately 860,000 light years away. He used Harvard’s Henrietta Leavitt’s formula to calculate this. The Andromeda galaxy is also known as M31, is the closest large spiral galaxy to ours. Excluding large and small Magellanic Clouds, the Andromeda galaxy, is the brightest galaxy.