McDonald Observatory Celebrates First Anniversary of Greater Big Bend International Dark Sky Reserve as Sky Becomes 3% Darker

McDonald Observatory and numerous partners are celebrating the first anniversary of the Greater Big Bend International Dark Sky Reserve, which covers more than 15,000 square miles in Texas and Mexico and is the largest dark sky place in the world certified by the International Dark-Sky Association (IDA). The observatory’s ongoing conservation work, including its support of the Reserve, has helped to ensure that it maintains the darkest skies of any research observatory in the continental United States.

What’s remarkable is that combining measurements of light pollution levels from all-sky photometry and contributions from volunteers using sky quality meters, the data reveal that the skies have become nearly 3% darker on average over the last year, a significant accomplishment considering light pollution is increasing by an estimated 9.6% annually in North America. This progress is a result of efforts to preserve the night skies in the region, including the establishment of the Reserve through a diverse collaboration between communities, parks, and organizations.

Dark skies are crucial for preserving the natural beauty of the night sky and reducing the negative impacts of light pollution on scientific observations, human health, wildlife, and the environment. McDonald Observatory, in partnership with the IDA, will participate in Dark Sky Week from April 18-22, an annual event to raise awareness about the adverse effects of light pollution and the importance of preserving dark skies. During the week of celebrations, McDonald Observatory will host a series of events along with its regular programs, including pop-up labs and talks on topics ranging from archeoastronomy to nature’s need for darkness. Visitors may also participate in special tours of the observatory facilities and learn more about the state-of-the-art equipment used to study the night sky.

The success of the Greater Big Bend International Dark Sky Reserve has been made possible through funding from Apache Corp., who have been strong allies and champions of night sky-friendly lighting in the Permian Basin. McDonald Observatory extends its deepest gratitude to Apache Corp. for their unwavering support and partnership in preserving the natural beauty of the night sky and promoting the conservation of night skies.

McDonald Observatory encourages visitors to come and experience the wonders of West Texas’s dark skies and practice night sky-friendly lighting. For more information on light pollution, the Greater Big Bend International Dark Sky Reserve, and the events at McDonald Observatory, visit

Image by Stephen Hummel, McDonald Observatory


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