But the biggest galaxy of all? That’s IC 1101. The giant galaxy cluster, Abell 2029, houses galaxy IC 1101 at its core. At 5.5 million light years across, over 100 trillion stars and the mass of nearly a quadrillion suns, it’s the largest known galaxy of all. As massive and impressive as this galaxy cluster is, it’s unfortunately difficult for the Universe to make something significantly larger owing to its finite age and the presence of dark energy. Credit: NASA/Digitized Sky Survey 2 Half its light is contained within a central, 2 million light-year radius.