... Distortion from a Distant Cluster . ... Hardly noticeable in the original picture is the small cluster of about 15 galaxies nearly 3 billion light-years distant , circled at the lower right. ... As predicted by Einstein's General Relativity theory, the cluster's gravitational mass acts like a lens, bending light and distorting the shape of background galaxies. ... Publications with keywords: gravitational lens - galaxy cluster . Publications with words: gravitational lens - galaxy cluster . ...