than 2.2 billion light-years away, for more than 13 hours. The gravity of the cluster’s trillion stars, plus dark matter, acts as a 2-million-light-year-wide “lens” in space. This “gravitational lens” ...

The Hubble Space Telescope as seen from the Space Shuttle Discovery in December 1999. Credit: NASA In the summer of 1995, Robert Williams, then director of the Space Telescope Science Institute, which ...