Object Analysis

The Black Eye Galaxy (Messier 64) is a spiral galaxy located in the constellation Coma Berenices, roughly 24 million light-years from Earth. It is instantly recognizable by the spectacular dark band of absorbing dust in front of the galaxy's bright nucleus, giving rise to its nicknames "Black Eye" or "Evil Eye" galaxy.

M64 is unusual because its outer regions rotate in the opposite direction to the inner regions. The inner region, about 3,000 light-years in radius, rubs along the outer disk, which extends to 40,000 light-years. This shear region is a site of active star formation, indicated by blue knots of young stars.

Astronomers believe this counter-rotation is the result of a collision between M64 and a smaller satellite galaxy more than a billion years ago. The smaller galaxy was accreted, but its orbital momentum was conserved, leading to the backward motion of the outer gas.