In this composite image of the spiral galaxy NGC 4921, formed from 80 individual Hubble Space Telescope exposures, more distant galaxies are visible through the spiral's translucent dust ring. NGC 4921 is classified as an anemic spiral—its star formation rate is lower than most galaxies of its type, hence its relative transparency in this view. The spiral is found in the Coma galaxy cluster, a grouping of more than 1,000 galaxies about 320 million light-years away in the northern constellation Coma Berenices.