Galaxy clusters are the largest stable systems in the Universe. They can contain thousands of galaxies all held together by the glue of gravity. A spectacular new image from the NASA/ESA Hubble Space Telescope shows one of these colossal systems — a galaxy cluster called SDSS J0333-0651. At first glance, this Hubble image is dominated by the glow of the swirling spiral to the lower left of the frame. However, this galaxy is far from the most...
