The heaviest confirmed black hole yet discovered lies at the center of the elliptical galaxy NGC 4889, which is the large blue-green object at left in this combination infrared and visible-light image. By measuring the orbital speeds of stars in the galaxy, a team of astronomers determined that the black hole is 9.8 billion to 27 billion times the mass of the Sun, with 21 billion as the most likely number. NGC 4889 is about 350 million light-years away, and is a member of a giant cluster of galaxies known as the Coma Cluster. NGC 4889 is one of the largest galaxies in the cluster (along with NGC 4874, at right in this image). It is much larger and more massive than our own galaxy, the Milky Way. In this image, blue and green represent visible light while red represents infrared. [NASA/JPL/Caltech/L. Jenkins (GSFC)]