Sometimes false-color imagery is more fantastic and thrilling to behold than the natural-color object; in this case, both versions are gorgeous, but this one has the added benefit of being purple:
In a break from its usual task of searching for distant cosmic explosions, NASA’s Swift satellite acquired the highest-resolution view of a neighboring spiral galaxy ever attained in the ultraviolet. The galaxy, known as M31 in the constellation Andromeda, is the largest and closest spiral galaxy to our own. This mosaic of M31 merges 330 individual images taken by Swift’s Ultraviolet/Optical Telescope. The image shows a region 200,000 light-years wide and 100,000 light-years high (100 arcminutes by 50 arcminutes).
The above image is cropped; go to the NASA page for uncropped download sizes (wallpapers and the like.)