Messier 63 (also known as M63, NGC 5055, or the Sunflower Galaxy) is a spiral galaxy in the constellation Canes Venatici. It consists of a central disc surrounded by many short spiral arm segments. This galaxy form is known as flocculent. M63 is part of the M51 Group, a group of galaxies that includes M51 (the 'Whirlpool Galaxy'). M63 is an active galaxy with a LINER nucleus. The existence of a super massive black hole at the nucleus is uncertain; if it does exist, then the mass is estimated as (8.5±1.9)×108 M☉.