In 1995, astronomers aimed the Hubble Space Telescope at a tiny patch of sky that looked almost empty — a dark spot near the Big Dipper no wider than a pinhead held at arm’s length. After 10 days of exposures, the darkness resolved into roughly 3,000 galaxies, hiding in a place where the human eye saw nothing at all.

In 1995, astronomers aimed the Hubble Space Telescope at a tiny patch of sky that looked almost empty — a dark spot near the Big Dipper no wider than a pinhead held at arm’s length. After 10 days of exposures, the darkness resolved into roughly 3,000 galaxies, hiding in a place where the human eye saw nothing at all.

In December 1995, the Hubble Space Telescope spent ten days looking at a part of the sky that had been chosen because it seemed so empty. The target lay near the handle of the Big Dipper, in the northern constellation Ursa Major, far from the bright plane of the Milky Way and away from obvious foreground clutter. To the human eye, there was nothing there. That was the point. Robert Williams, then director of the Space Telescope Science Institute…