Hubble stared at an empty speck of sky and found 3,000 galaxies

The Hubble Space Telescope launched aboard Space Shuttle Discovery on April 24, 1990, and after a famously rocky start — a flawed primary mirror, corrected by a daring 1993 servicing spacewalk — it began rewriting astronomy.

Its boldest gamble came in December 1995, and it was as much an institutional risk as a scientific one. Director Robert Williams spent a large chunk of his discretionary observing time on a target many colleagues considered a waste: a deliberately dull, near-empty scrap of sky near the Big Dipper, no bigger than a grain of sand held at arm’s length. The patch was chosen precisely because it looked boring — well away from the bright stars and dust of our own galaxy’s plane, and in a spot Hubble could stare at continuously without Earth getting in the way.

Over ten consecutive days and 342 exposures, the dark filled in. The Hubble Deep Field revealed roughly 3,000 galaxies, many billions of light-years off and seen as they looked in the universe’s youth. Because looking far into space means looking back in time, the image became a core sample drilled through cosmic history.

Later telescopes drilled deeper into the same dark. The Hubble Ultra Deep Field of 2004 pulled out around 10,000 galaxies from an even tinier patch, and the James Webb Space Telescope now resolves galaxies that existed just a few hundred million years after the Big Bang.

The lesson held: almost any blank-looking direction is crowded, and emptiness, in space, is largely an illusion.