M 63

Messier 63, also known as NGC 5055 or “Sunflower Galaxy”, is a spiral galaxy in the northern constellation of Canes Venatici with approximately 400 billion stars. M63 was first discovered by the French astronomer Pierre Méchain, then later verified by his colleague Charles Messier on 14 June 1779. The galaxy became listed as object 63 in the Messier Catalogue. In the mid-19th century, Anglo-Irish astronomer Lord Rosse identified spiral structures within the galaxy, making this one of the first galaxies in which such structure was identified. M63 is part of the M51 Group, a group of galaxies that also includes M51 (the 'Whirlpool Galaxy').

The distance to M63, based upon the luminosity-distance measurement is 29 million light-years.

The shape or morphology of this galaxy has a classification of SAbc,  indicating a spiral form with no central bar feature  and moderate to loosely wound arms. M63 is a weakly active galaxy with a LINER nucleus – short for 'low-ionization nuclear emission-line region'. Radio observations at the 21-cm hydrogen line show the gaseous disk of M63 extends outward to a radius of 130,000 light-years (40 kiloparsecs), well past the bright optical disk.