IAU recommends stronger protection for astronomical observation sites

The International Astronomical Union (IAU), in collaboration with the United Nations, has recently released updated recommendations aimed at safeguarding astronomical observation sites from artificial light pollution. Drawing from the conclusions of two international workshops, “Dark and Quiet Skies for Science and Society” (D&QS) held in 2020 and 2021, these guidelines address the escalating issue of Artificial Light at Night (ALAN).

The original 1979 IAU standard, which permitted up to 10% artificial light above natural background levels, has become insufficient for contemporary observatories, often located in remote, naturally dark areas. The new recommendations emphasize the necessity of significantly stricter controls to preserve these critical sites.

Key measures include stopping and eventually reversing the growth of artificial lighting over the coming decade, maintaining ALAN well below the previous 10% threshold, and addressing light pollution directly at its sources, notably in urban, industrial, and agricultural areas. Each observatory should set specific, measurable limits based on the local ALAN contribution and its rate of growth, ensuring that future developments do not compromise observational quality.

The IAU is currently preparing a resolution based on these recommendations for consideration at its 2027 General Assembly.

For the full report and detailed guidelines, please refer to the original article on the IAU official website.

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