Messier 63 (NGC 5055), nicknamed the Sunflower Galaxy, is a beautiful spiral galaxy in the constellation Canes Venatici.
M 63 was the very first discovery of Charles Messier's friend, Pierre Mechain, who caught it on June 14, 1779. On the same day, Charles Messier included it as the 63rd object in his catalog. The Sunflower galaxy is one of the earliest-recognized spiral galaxies, listed by Lord Rosse as one of the fourteen "spiral nebulae" known up to 1850.
Messier 63 has a visual magnitude of 8.6, and apparent dimensions of 10'x 6'. Its spiral pattern resembles a giant celestial sunflower: a large central hub surrounded by tightly wound spiral arms. M 63 has been classified as type Sb or Sc, displaying a patchy spiral pattern; its spiral features are in a multitude of short arcs rather than long well-defined arms.
The spiral arms show up as a grainy background, which brighten slowly from outward and then rapidly inward to the 6"-wide nuclear region, which is still grainy. Star forming regions can be traced all along the spiral arms on color photos.
The type I supernova 1971I was discovered in M 63 on May 25, 1971, and reached magnitude 11.8.
The distance to M 63 is about 37 million light years, and it has a diameter of some 90,000 light years. Although it appears 6° south of the Whirlpool Galaxy (M 51), it apparently forms a physical group with that galaxy and several others, known as the M 51 Group.