M63, the Sunflower Galaxy is a beautiful and spectacular spiral galaxy in the constellation of Canes Venatici. Along with M51 "The Whirlpool Galaxy", M94 and M106 it's one of four Messier galaxies located in the constellation. Of these, M51 is a much studied interacting grand design spiral that claims the title of finest galaxy in Canes Venatici. However, M63 is only marginally fainter and not far behind its illustrious neighbour. In addition, M63 and M51 are gravitationally bound and along with at least 6 other smaller galaxies they form the M51 Group of galaxies.
M63 is best seen from the Northern Hemisphere during the months of March, April or May.
The galaxy was the very first discovery made by Pierre Mechain, the great friend of Charles Messier, who found it on June 14, 1779. On the same day, Messier included it in his catalogue. Although Canes Venatici is a faint constellation locating M63 is easy since we can use the famous Plough or Big Dipper asterism of Ursa Major as a starting point. First locate Alkaid (η UMa - mag. +1.9) the eastern and end star of the handle of the Plough. Imagine a line from Alkaid moving in a southwesterly direction for about 14 degrees. At the end of this line is the brightest star in Canes Venatici, Cor Caroli (α CVn - mag. +2.9). M63 is positioned about 2/3rds of the way along this line.
At magnitude +8.9, the Sunflower Galaxy is a challenging binocular object, appearing at best as an out of focus star. Through a 80mm (3.1 inch) refractor it's recognisable as a galaxy but shows no detail unless viewed with medium or larger amateur scopes. A 150 mm (6 inch) instrument at high power reveals a bright core surrounded by a smooth oval shaped patch of nebulosity. A scope of 200mm (8-inch) aperture will start to show the spiral structure including the short arm segments. More subtle details such as dust lanes are visible in even larger scopes.
M63 has an apparent size of 12.6 x 7.2 arc minutes and is located 37 Million light-years from Earth; equating to an actual diameter of 135,000 light-years. In the early 1800s, Lord Rosse identified spiral structure within the galaxy, making this one of the first galaxies in which such structure was identified. It was listed as one of 14 "spiral nebulae" discovered to 1850.
In 1971, a magnitude +11.8 supernova appeared in one of the arms of M63.
M63 Data Table
|Object Type||Spiral galaxy|
|RA (J2000)||13h 15m 49s|
|DEC (J2000)||42d 01m 50s|
|Apparent Size (arc mins)||12.6 x 7.2|
|Number of Stars||>400 Billion|
|Notable Feature||Member of the M51 Group of galaxies|