Big Bend Ranch State Park



Tools for monitoring the night sky visibility at Big Bend Ranch State Park, Barton Warnock Visitor Center and Fort Leaton State Historic Site.

Darkest Skies in Texas

Sunset over the Park HQ.

black & white dark sky park logoFor the best night skies in Tex­as, head west. Big Bend Ranch State Park sits in the darkest area of the state. After all, we are on the other side of nowhere.

The International Dark-Sky Association designated Big Bend Ranch State Park a gold tier Dark Sky Park in 2018.

The best places places for stargazing are along River Road, at the West Contrabando Trailhead, Big Hill and the Hoodoos. These spots offer great views, and are accessible by any vehicle.

Check out these free stargazing tools:

How Dark Is It?

The Bortle Dark-Sky Scale measures how well you can see objects in the sky at night. Light pollution and sky glow can interfere with your ability to see “celestial objects.”

The scale ranges from Class 1, the darkest skies available on Earth, through Class 9, inner-city skies. Big Bend Ranch’s Bortle Scale rating is 1 in some areas. Barton Warnock Visitor Center has a 2 rating, while Fort Leaton has a 4. (Visit Bortle Scale Ratings page to see ratings for all state parks.)

The map below shows the sky glow around the park with colors that match the Bortle scale.

ERSNA Light Pollution Map
Big Bend Ranch Light Pollution Map. The park is at the crosshairs.

Dark Sky Measurements

On a moonless night in April 2017, rangers set out to measure the darkness. They took 39 readings at 13 sites in the park using a hand-held photometric device called a Sky Quality Meter (SQM).

The SQM measures the amount of artificial light in the sky at a given time. The output represents sky brightness in magnitudes per square arc second. The higher the output number, the darker the sky.

The mean SQM reading for that night was 21.73. According to the International Dark Sky Association guidelines, a value between 21 and 22 is considered exceptionally dark.

Clear Sky Chart

A Clear Sky Chart is an astronomer’s forecast about sky conditions, including, darkness, cloudiness, transparency and the seeing quality. More information about the Clear Sky Chart can be found here.

Big Bend Ranch's clear sky chart

The rising and setting of the moon, the Milky Way passing directly overhead, and man-made light can cause fluctuations in sky darkness.

To learn more, look up current moon phase information for Big Bend Ranch State Park or see the current moon phase calendar.

Become a Dark Sky Steward

We are looking for volunteers to help us watch the night sky. We can use your observations and photographs to monitor sky quality. We may waive camp or park entrance fees for volunteers who sign up and provide observations and/or images.

Visit our Volunteer page or contact Barton Warnock Visitor Center at (432) 424-3327 to sign up or learn more.