Dark Skies Council: International astronomical observatories join forces to protect Chile’s skies

• Faced with the growing risk that light pollution poses to the development of astronomy in Chile, the main international observatories operating in the country have formed a joint organization dedicated to protecting the dark skies of northern Chile.

• The council will act through the Cielos de Chile Foundation and the Office for the Protection of the Quality of the Northern Chilean Sky (OPCC), with the aim of coordinating strategies and articulating actions to combat the advance of light pollution.

Light pollution is growing by 9.6% each year, according to a study published in Science journal. Chile’s skies are also being affected by this phenomenon, and it is estimated that a 10% increase in sky brightness would mean a 12.07% loss in the original capacity of optical telescopes located in the country.

In response to this problem, the Association of Universities for Research in Astronomy (AURA), the Giant Magellan Telescope (GMT), the European Southern Observatory (ESO), and Las Campanas Observatory—part of the Carnegie Institution for Science—signed an agreement to create the Dark Skies Council. Through this alliance, the institutions will work in a coordinated manner to protect Chile’s privileged skies.

The signatory institutions manage some of the largest and most advanced optical observatories in the world, all located in Chile: AURA is in charge of the Cerro Tololo Observatory, Gemini South, and the mega Vera C. Rubin Observatory, currently under construction; the Giant Magellan Telescope (GMT), also under construction, will be installed at Las Campanas, where the Carnegie Institution for Science currently operates its observatory; while ESO operates observatories in Paranal and La Silla and will soon operate the Extremely Large Telescope (ELT), under construction in Cerro Armazones.

The importance of protecting dark skies

Thanks to the exceptional quality of its skies, Chile now accounts for nearly 40% of the world’s astronomical observation capacity. In the last two decades, the number of astronomical institutions in the country has doubled, and the number of people dedicated to this science has tripled. In addition, three mega-telescopes, which will be among the largest in the world, will be installed in the coming years, with a total investment of more than US$5 billion. Their operation will allow Chile to exceed 60% of global astronomical observation capacity by 2030.

However, this leadership is at risk. The sustained increase in sources of light pollution from urban centers, industrial and mining operations, ports, and highways threatens the natural darkness of the night sky in the regions of Antofagasta, Atacama, and Coquimbo, key areas for astronomy. “The quality and darkness of the night sky are fundamental to the scientific operations of our observatories. Preserving the dark skies of northern Chile is a priority for the signatory institutions, as the continuity of their present and future activities depends on it,” states the signed agreement.

What is the Dark Skies Council and who are its members?

The Dark Skies Council is composed of six representatives from the observatories and its main mission will be to define and monitor the implementation of a common strategy to protect the dark skies. Its functions include coordinating activities with the Northern Chile Sky Quality Protection Office (OPCC) and the Cielos de Chile Foundation, as well as managing and allocating resources to implement specific initiatives in the territory.

The OPCC works to protect dark skies, which are essential for astronomy, and provides technical support to facilitate the implementation of light pollution regulations in the regions of Antofagasta, Atacama, and Coquimbo. For 25 years, it has collaborated with municipalities, local communities, and regional actors to promote actions for the prevention and reduction of this type of pollution.

For its part, the work of the Cielos de Chile Foundation has focused on the conservation of night skies as the country’s natural, scientific, and cultural heritage, and promotes the responsible use of artificial light for the benefit of science, biodiversity, human health, and sustainable tourism.

The Council appointed Oscar Contreras, who is Vice President and Representative in Chile for GMT, as its first Director. Contreras has extensive experience at the intersection of science, public policy, and conservation.

In this way, as Chile strengthens its leadership in dark sky protection, the launch of the Dark Sky Council marks a new era characterized by proactive stewardship to preserve one of Earth’s most important windows to the cosmos.