An international team of astronomers using NASA’s Hubble Space Telescope has discovered a puzzling arc of light behind an extremely massive cluster of galaxies residing 10 billion light-years away. Galaxy cluster IDCS J1426.5+3508 and the giant arc (NASA / ESA / A. Gonzalez, University of Florida / A. Stanford, University of California and Lawrence Livermore National Laboratory / M. Brodwin, University of Missouri-Kansas City and Harvard-Smithsonian...