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).

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.

"Photographing Andromeda was a herculean task because the galaxy is a much bigger target on the sky than the galaxies Hubble routinely observes, which are often billions of light-