(light entertaining music) - [Instructor] McDonald Observatory sits perched 6,800 feet high atop the Davis Mountains of West Texas.

On any clear night, as the sun sets, the massive steel and aluminum doors of these domes slowly open revealing highly tuned telescopes.

Their purpose to collect light and see what the naked eye cannot observe.

Astronomers point the 160 to 180-ton steel cylinders at tiny patches of the sky.

This part of west Texas offers some of the darkest and clearest skies in the country making it an ideal location for stargazing.

First of three telescopes was dedicated in 1939.

It's named the Otto Struve, but it's known simply as the 82-inch.

It has given astronomers access to distant galaxies discovering stars in the Milky Way and new moons around Uranus and Neptune.

(light entertaining music) 30 years later, in 1969, the observatory added an even larger telescope that helped better determine the distance to the moon.

Today it is used every night to study the compositions of stars, and unmask the chemistry of galaxies and interstellar matter.

In 1997, the University of Texas and four partner universities unveiled one of the largest optical telescopes in the world.

Astronomers manipulate the 80-ton instrument to find galaxies at the known edge of the visible universe, and study dark energy, a mysterious force thought to cause the universe's accelerating rate of expansion.

The massive machine rotates effortlessly on cushions of air, while its tracker is focused on 91 hexagonal mirrors that create a honeycomb.

Every year, around 75,000 visitors come for Tours and Star Parties.

Here, the massive domes of the telescopes hover over the earthly environment where the stars truly shine big and bright.

- [Narrator] Funding for The Shape of Texas is provided by Texas Society of Architects, and by a grant from Humanities Texas, the state affiliate of National Endowment for the Humanities and The Summerlee Foundation of Dallas, Texas.