In 1995, astronomer Bob Williams wanted to point the Hubble Space Telescope at a patch of sky filled with absolutely nothing remarkable. For 100 hours.

It was a terrible idea, his colleagues told him, and a waste of valuable telescope time. People would kill for that amount of time with the sharpest tool in the shed, they said, and besides — no way would the distant galaxies Williams hoped to see be bright enough for Hubble to detect.

Plus, another Hubble failure would be a public relations nightmare. Perceptions of the project, which had already cost multiple billions of dollars, were pretty dismal. Not much earlier, astronauts had dragged Hubble into the cargo bay of the space shuttle Endeavour and corrected a