... In the center of M51, a spiral galaxy 23 million light-years away, astronomers have identified a dense region of young stars. ... Giant Cluster Bends, Breaks Galaxy Images . ... Cluster galaxies here appear yellow and -- together with the cluster's dark matter -- act as a gravitational lens. Comet Hyakutake on a Starry Night . ... It was a starry night in April (April 9th, 1996, 9:32 pm CDT to be exact) near Lone Jack, Missouri when Comet Hyakutake graced this astronomically rich field. ...