This space wallpaper is of the famous early-type spiral galaxy Messier 104, widely known as the "Sombrero" (the Mexican hat) because of its particular shape. The "Sombrero" is located in the constellation Virgo (The Virgin), at a distance of about 50 million light-years. Messier 104 is the 104th object in the famous catalogue of nebulae by French astronomer Charles Messier (1730 - 1817). It was not included in the first two editions (with 45 objects in 1774; 103 in 1781), but Messier soon thereafter added it by hand in his personal copy as a "very faint nebula". The recession velocity, about 1000 km/sec, was first measured by American astronomer Vesto M. Slipher at the Lowell Observatory in 1912; he was also the first to detect the galaxy's rotation.
(Image: © ESO/P. Barthel Acknowledgments: Mark Neeser (Kapteyn Institute, Groningen) and Richard Hook (ST/ECF, Garching, Germany).)