A new study conducted by researchers from Italy, Chile, and Galicia reveals that light pollution is significantly affecting the skies above many of the world’s major astronomical observatories. The study, published in Monthly Notices of the Royal Astronomical Society, emphasizes the urgent need for measures to reduce artificial light contamination to preserve the efficacy of ground-based astronomy.
The research team examined light pollution levels at nearly 50 observatories globally, including both large professional facilities and smaller amateur observatories. Utilizing a model that simulates light propagation in the Earth’s atmosphere and incorporating night-time satellite data, the study provides a comprehensive overview of the current state of light pollution at these sites.
Traditional assessments of light pollution often focus on the brightness at the zenith, the point directly overhead. However, this study expanded the evaluation to include additional indicators such as average brightness at 30° and 10° above the horizon, overall sky brightness, and ground illuminance from artificial light. These additional metrics offer a more detailed understanding of how artificial light impacts the night sky.
The results are concerning: only 7 out of the 28 major observatory sites (those with telescopes 3 meters or larger in diameter) have a zenith sky brightness with light pollution below the 1% threshold of natural sky brightness. This indicates that three-quarters of these major observatories are experiencing significant light pollution. Furthermore, at the lower observation angle of 30° above the horizon, only one observatory meets the 1% pollution threshold. A more lenient 10% limit set by the International Astronomical Union in the 1970s has also been surpassed by two-thirds of the sites in the study.
Dr. Fabio Falchi, the lead researcher, highlighted the severity of the issue, stating, “The least contaminated of all the sites in the study is a lodge in Namibia that hosts several telescopes for amateur astronomers. It is the least light-polluted site I’ve ever seen.” He stressed the need for immediate action to reduce light pollution at other observatories to safeguard the future of ground-based astronomy.
This study underscores the critical impact of artificial light on astronomical observations and the necessity for concerted efforts to mitigate light pollution to protect the integrity of scientific research conducted at these observatories.
Reference: https://www.ras.ac.uk/news-and-press/research-highlights/three-quarters-major-observatories-affected-light-pollution