Big Bend National Park in Texas has just become part of the largest dark sky reserve in the world. It's also the first to be international, crossing the border between the US and Mexico. The goal of creating dark sky reserves is to minimize the spread of light pollution by adopting night-sky friendly practices.

The Greater Big Bend International Dark Sky Reserve is around 40,000 square kilometers (over 15,000 square miles) and will benefit local communities, wildlife, astronomers, tourists, and businesses.

It took the joint efforts of the University of Texas at Austin’s McDonald Observatory, the Nature Conservancy, the International Dark-Sky Association (IDA), National Park Service, Texas Parks and Wildlife Department, and the National Commission of Natural Protected Areas in Mexico, as well as local organizations and businesses, to create the incredible area.

“Without the broad regional support and the long-standing efforts to preserve the natural beauty of the Big Bend region, a dark sky reserve of this scale would not have been possible,” Teznie Pugh, Superintendent of McDonald Observatory, said in a statement. “It has been a true community effort, and the people of the area should be proud of what we have all achieved together.”

The reserve will be divided into a core area around Davis Mountain Preserve, the location of the McDonald Observatory, where the most stringent light rules will be in place, and the wider supporting areas where light pollution will be minimized without disrupting the lives of the inhabitants.

“This reserve protects both the scientific research and public education missions of McDonald Observatory,” said Observatory director Taft Armandroff. “Since 1939, the observatory has enabled the study of the cosmos by faculty, students, and researchers at UT Austin and other Texas institutions of higher learning, with topics ranging from planets orbiting nearby stars to the accelerating expansion of the universe.”

“We are honored to be a part of the Greater Big Bend International Dark Sky Reserve,” said Kaylee French, education and outreach coordinator for the Davis Mountain Preserve. “This collaboration uniquely brings together working partners across a wide range, which spans international borders. Our dark skies are an invaluable natural resource that we are able to preserve only by working together, and we thank the International Dark-Sky Association for helping us to be responsible stewards of this now and forever protected resource.”

Dark Sky reserves have many benefits. The lighting practices employed increase safety and reduce energy, while allowing residents (human or otherwise) to enjoy the day and night cycle.

“The certification of this reserve is truly a historic moment for the dark sky movement,” said Ashley Wilson, IDA’s director of conservation. “We are recognizing decades of hard work, nocturnal environmental stewardship, stellar outreach programs, and multiple local incentives to provide tangible and feasible solutions that limit the spread of excessive and wasteful artificial light. This demonstrates that partnerships and dark sky efforts at the landscape scale can become a reality with the dedication from a team of key stakeholders and passionate communities.”