The Andromeda galaxy is a colossal marvel in our sky, hosting over 1 trillion stars. Now, astronomers have used the Hubble Space Telescope to capture hundreds of detailed images of our vast galactic neighbor, creating the largest-ever photomosaic of the galaxy. It took over 10 years to create.

Messier 31 is located 2.5 million light-years away from Earth and was a much bigger target in the sky than the galaxies Hubble routinely observes.

In the years following the launch of NASA's Hubble Space Telescope, astronomers have tallied over 1 trillion galaxies in the universe. But only one galaxy stands out as the most important nearby stellar island to our Milky Way—the magnificent Andromeda galaxy (Messier 31).