False-color image of IC 1101 at the center of the galaxy cluster Abell 2029. It was the cover image of the Science issue of October 26, 1990

IC 1101, the Largest of All Galaxies

An elliptical supergiant with a diameter of just under eight million light-years

In the Yerkes classification system, the abbreviation cD is reserved for the largest galaxies [1]. The lowercase ‘c’ indicates that the galaxy is a supergiant, while the letter ‘D’ means that a large halo of diffused light surrounds it. It implies that cD galaxies have…