A giant elliptical galaxy called Messier 87 merged with a medium-sized spiral galaxy in the last billion years, according to a comprehensive study of 300 planetary nebulae in the Messier 87 halo observed by ESO’s Very Large Telescope (VLT). The huge halo around the giant elliptical galaxy Messier 87 appears on this image. The image also reveals many other galaxies forming the Virgo Cluster, of which Messier 87 is the largest member. Image credit:...
