M64 has two counter-rotating systems of stars and gas in its disk: an inner zone, about 3,000 light-years in radius, that rubs along the inner edge of an outer disk, which rotates in the opposite direction at about 300 km/s and extends out to at least 40,000 light-years. This rubbing may explain the vigorous burst of star formation that is currently taking place in the galaxy and is visible as blue knots embedded in the huge dust lane.