Two billion years after the cosmos banged into existence, a mysterious force known as dark energy began shoving space outward, causing the universe to balloon faster and faster and threatening to one day rip apart everything within it, from clusters of galaxies to particles inside atoms.

Astronomers have taken on the behemoth task of figuring out the fate of our nearly 14-billion-year-old universe by understanding what dark energy is, and how exactly it works. But on Earth, they can do so only under the darkest of night skies. For a team of researchers, that meant setting up shop at the McDonald Observatory in the remote Big Bend region of West Texas, in the biggest dark-sky reserve on the planet.

“We wanted to go for the most distant objects that we could see on a telescope,” said Karl Gebhardt, an astronomer at the University of Texas at Austin and the father of the Hobby-Eberly Telescope Dark Energy Experiment, or HETDEX. Those objects, he explained, are galaxies as far away as 12 billion light-years, and they are faint enough to be obscured by the brightness of the full moon, or too many well-lit storefronts.

The dark skies of Big Bend enabled the HETDEX team to collect data from 2017 to 2024; now, Dr. Gebhardt and his colleagues are on the cusp of their first major result. But the region’s starry nights are valued for far more than their scientific merit. They have also inspired an ecosystem of dark-sky advocacy that extends beyond astronomers’ desire to decipher the universe, particularly as light pollution encroaches on the ability to see the stars.