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The world's largest international dark sky reserve is helping UT scientists study the universe

The McDonald Observatory sits under a night sky full of stars.
Gabriel C. Pérez
/
KUT
An International Dark Sky designation is helping scientists at the McDonald Observatory in West Texas study the expansion of the universe.

The images from NASA’s James Webb telescope are some of the most breathtaking we’ve ever seen, showing a handful of the very first galaxies that formed after the Big Bang. Researchers at UT Austin’s McDonald Observatory are doing their part to understand our universe, as well.

The largest telescope at the McDonald Observatory, Hobby-Eberly, is creating a map of the universe to study and measure its expansion.

An International Dark Sky designation is helping the observatory by keeping the skies dark and reducing light pollution.

“We need dark skies to study the universe because galaxies are very faint, fainter than the faintest star you could see with the naked eye,” said Stephen Hummel, the dark skies initiative coordinator at the McDonald Observatory.

International Dark-Sky Designation

Located in Fort Davis, the McDonald Observatory is part of a newly designated dark sky reserve — the largest one in the world.

In April, the International Dark Sky Association, or IDA, designated 15,000 square miles of western Texas and northern Mexico the Greater Big Bend International Dark Sky Reserve.

The dark sky designation is reserved for areas that have "exceptional" starry night potential as well as scientific, natural, educational, cultural, heritage, and tourism purposes.

“Preserving the night sky and eliminating wasted light is important because there are fewer and fewer places in the world where you can see a truly dark night sky,” Hummel said. “Entire generations are growing up never experiencing a truly dark sky, which I think is a loss of culture.”

In addition to its size, the reserve is unique because of the variety of partners involved. The National Parks Service, Texas Parks & Wildlife, Mexico, several nonprofits and 11 communities and counties in Texas came together to adopt the dark sky ordinance.

Dark Sky Ordinance

A dark sky ordinance requires all structures, including city-owned buildings and private residences, to use shielded, amber lights aimed at the ground. Although the ordinance is the law, it’s not strictly enforced.

“The goal of a dark sky reserve is not to enforce total darkness on everyone,” Hummel said. “The goal is to use light intelligently, using it where it’s needed and not wasting it.”

Globally, light pollution increases 2% every year, according to the IDA. Light pollution can have drastic consequences for humans, animals and plants.

Almost all life on earth has evolved and adapted to a day/night cycle, our circadian rhythm. But too much exposure to artificial light at night messes up our body clocks.

For humans, the effects of light pollution are correlated with depression, cancer, diabetes and heart disease.

Light pollution also negatively impacts wildlife migration patterns and plants’ growth cycles. Trees, for instance, use light to determine when to grow or lose their leaves. Artificial night light can confuse them about which season it is.

“It’s a huge body of growing science studying the effects of light pollution on our health and wildlife,” Hummel said. “And the answer is pretty clear that it’s wreaking havoc. We’re really just now beginning to realize the full effect.”

Fortunately, you don’t have to be part of a reserve to use better lighting. Hummel suggests three things you can do right now to reduce light pollution in your community:

  1. Aim your lights down;
  2. Avoid bright white or blue lights, as they’re worse for our circadian rhythm; and
  3. Ask yourself, do I really need a light? If the answer’s no, turn it off or put it on a timer.

Night sky friendly lighting “not only reduces energy waste, but it usually provides more light where you actually need it, increasing visibility and safety overall,” Hummel said. “So, it’s not that we have to make any sacrifices, it’s just a smarter way of lighting.”

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