A Faster, Lighter Camera for Measuring Dark Night Skies in National Parks

More than 80% of the world's people live under light pollution at night, which can harm human, animal and ecosystem health. Citizen scientists report that light pollution is growing by 7–10% a year. Many U.S. national parks are among the last places on Earth with truly dark skies, and visitors come to them for a rare look at the Milky Way. So the National Park Service keeps a close watch on how bright the night sky is in its parks.

A processed and annotated Fisheye Night Sky Imager photo from Black Canyon of the Gunnison National Park. NPS.

The old way

Since the 2000s the agency has measured night skies with wide-field charge-coupled device (CCD) camera systems. They have limits — for one, observers can only take pictures on clear, moonless nights.

The new camera

Scientists have now built a new system for measuring night-sky light pollution, the Fisheye Night Sky Imager, and described it in the August 2024 issue of Publications of the Astronomical Society of the Pacific. According to the researchers, it:

• photographs the entire night sky in just 30 seconds;
• is light, portable and quick to set up;
• can measure sky brightness even in poor conditions, including under clouds;
• comes with customized, free, open-source software to process the images — the first of its kind.

Sources

• The editors of Park Science: "Unique Night-Sky Camera System is Faster, Lighter, and More Versatile," Research Roundup, Park Science 39(1), Winter 2024–25, National Park Service; summarizing Hung and others (2024), "Fisheye Night Sky Imager: A Calibrated Tool to Measure Night Sky Brightness," Publications of the Astronomical Society of the Pacific 136: 085002.