Sombrero Galaxy (also known as Messier Object 104, M104 or NGC 4594) is an unbarred spiral galaxy in the constellation Virgo located 31 million light-years (9.5 Mpc)[2] from Earth. The galaxy has a diameter of approximately 50,000 light-years, 30% the size of the Milky Way.

It has a bright nucleus, an unusually large central bulge, and a prominent dust lane in its inclined disk. The dark dust lane and the bulge give this galaxy the appearance of a sombrero.

Astronomers initially thought that the halo was small and light, indicative of a spiral galaxy, but Spitzer found that the halo around the Sombrero Galaxy is larger and more massive than previously thought, indicative of a giant elliptical galaxy.[3] The galaxy has an apparent magnitude of +9.0, making it easily visible with amateur telescopes, and it is considered by some authors to be the brightest galaxy within a radius of 10 megaparsecs of the Milky Way.[4]

Its large bulge, its central supermassive black hole, and its dust lane all attract the attention of professional astronomers.