Our home galaxy, the Milky Way, belongs to a small cluster of galaxies – the Local Group. It has fewer than a hundred known members. But most galaxies reside in much more impressive clusters. And the closest of these is centered in the constellation Virgo, which steps up the eastern sky this evening.

The Virgo Cluster contains roughly 2,000 galaxies. They move through space together, bound by their mutual gravitational pull.

The cluster’s most impressive member is Messier 87. It marks the center of the cluster, more than 50 million light-years away.

M87 may span a million light-years and contain trillions of stars – many times the corresponding values for the Milky Way. And its total mass is more than twice the Milky Way’s.

M87 is a different type of galaxy. The Milky Way is a spiral – a flat disk highlighted by “arms” of bright stars that make it look like a pinwheel. M87, on the other hand, is elliptical – it resembles a fat, fuzzy football. It may have grown so large through the mergers of several big galaxies. That scrambled the stars, so they orbit the center of M87 in all directions.

The heart of the galaxy harbors a black hole more than a thousand times the mass of the central black hole in the Milky Way. It was the first black hole to have its picture taken – a dark shadow at the heart of a giant galaxy.

More darkness in Virgo tomorrow.

Script by Damond Benningfield