M31 Andromeda

The Andromeda Galaxy (also known as Messier 31, M31, or NGC 224) is a barred spiral galaxy and the nearest major galaxy to the Milky Way. Located approximately 2.5 million light-years from Earth in the constellation of Andromeda, it is the most distant object visible to the naked eye under dark skies, appearing as a faint, fuzzy smudge.

With a diameter of roughly 152,000 to 220,000 light-years, Andromeda is larger than the Milky Way and contains an estimated 1 trillion stars, significantly more than our home galaxy's 200–400 billion. Despite its larger stellar population, recent studies suggest the Milky Way may be more massive due to a higher concentration of dark matter.