**Background** In 1979, the International Astronomical Union defined a maximum level of light pollution below which a professional site could be considered adequate for true dark sky observing. This standard was defined as an upper limit of artificial light contribution of 10% above the natural background at an elevation of 45° in any azimuthal direction. Considerable work has been done in recent years to advance the protection of astronomical sites. In particular, this issue has been reported and discussed at two international workshops: The Dark and Quiet Skies (D&QS) for Science and Society 1 and 2. The first D&QS workshop[1], held in October 2020, was sponsored by the United Nations Office for Outer Space Affairs (UNOOSA), the International Astronomical Union (IAU), the Instituto de Astrofisica de Canarias in Spain (IAC), and the National Optical-Infrared Laboratories (NOIRLab) of the United States (US) National Science Foundation (NSF). The second workshop[2], held in October 2021, was sponsored by the same four organisations and the European Southern Observatory (ESO). These two workshops ultimately inspired the creation of the IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS) in 2022. The international working group for D&QS 1 consisted of nine astronomers, four technical experts in light pollution/modelling, seven lighting experts from the International Commission on Illumination (CIE), and two industry representatives, including one from the manufacturers' Global Lighting Association. The working group worked on its findings and conclusions for three months prior to the workshop, led an active discussion at the workshop, and incorporated further insights into the final report. The conclusions in the report were unanimously agreed by the Working Group and adopted as the outcome of the workshop. The international working group for D&QS 2 consisted of nine astronomers, 10 experts on various effects of light pollution, including on the natural world and public health, and a lighting engineer representing the CIE. Their task was to consider the broader aspects of artificial light at night and to develop further international guidelines based on the recommendations for site protection in D&QS 1. This working group invested a similar amount of effort (three months) prior to its workshop and followed a similar process to produce its report. The Summary Recommendation for the Protection of Astronomical Sites, presented below, is the result of the substantive deliberations of these UN/IAU-sponsored working groups with broad experience and expertise. The IAU is currently considering drafting a resolution based on these recommendations to be submitted for approval at its next general assembly in 2027. **Summary of the Recommendations of the Working Groups** Present-day professional observatories are located in remote, high-altitude locations; a key selection criterion is the actual sky darkness being as close to the natural background as possible. These sites have an artificial light contamination **significantly** below the 10% limit recommended by the IAU in 1979. Hence, this limit **is not appropriate** for the protection of modern professional astronomical sites. Adequate protection of major professional observatories requires actions to: 1. reduce, stop, and then reverse, on the timescale of a decade, the growth of Artificial Light at Night (ALAN); 2. keep the total contribution to skyglow from ALAN **substantially** below the 10% dark site limit defined by the IAU; and ultimately, 3. control and reduce light pollution where it is mainly produced: in human population centres including cities and towns, and in industrial and agricultural production centres. To achieve the necessary level of protection, each major professional observatory and controlling governmental body should agree on the total amount of outdoor light allowable, based on measurement and modelling of the current level and rate of change of ALAN impacting the site. **Illustration of the recommendations** The core of the recommendations is that each major site has a **unique limit** that should not be exceeded by growing ALAN. It requires each observatory to know what its ALAN contribution is and the rate at which it is currently growing, quantities that can be easily measured. For example, if an observatory has a current ALAN growth rate of 0.04% per year, which is to be brought to zero within five to eight years, then the ALAN contribution will be less than 0.5% for the foreseeable future. The condition that the ALAN growth rate must be brought to zero and reversed at a site that now has an extremely low artificial contribution sets strong constraints; there will be no way to accommodate a new major artificial light source within these rules, as there is no offset for any sources that could be reduced. ## Notes 1] [https://www.unoosa.org/oosa/en/ourwork/psa/schedule/2020/2020_dark_skies.html 2] [https://www.unoosa.org/oosa/en/ourwork/psa/schedule/2021/2021_dark_skies.html ## More information The IAU is the international astronomical organisation that brings together about 13,000 distinguished astronomers from around the world. Its mission is to promote and safeguard the science of astronomy in all its aspects, including research, communication, education and development, through international cooperation. The IAU also serves as the internationally recognised authority for assigning designations to celestial bodies and the surface features on them. Founded in 1919, the IAU is the world’s largest professional body for astronomers.

The annual call for the Teacher Training Programme (TTP) 2025, run by the IAU Office of Astronomy for Education (OAE), is now open. This is an opportunity for the OAE’s National Astronomy Education Coordinators (NAECs), astronomers, teachers, and anyone working in astronomy education to submit a proposal and host a teacher training workshop in their country or region. The deadline for submissions is 30 April 2025. One of the OAE’s objectives is to professionalise astronomy education. To this end, the OAE is dedicated to developing and implementing a framework in which astronomy teacher training programmes can be run and supported globally. For the 2025 edition of the TTP, the OAE is working on the “Transparency Standards for Astronomy Teacher Training Workshops”. These standards will serve as guidelines to help proposers of potential TTP workshops develop and refine their programmes, providing a structured approach to constructing workshop proposals, outlining key aspects such as content knowledge, pedagogy, classroom application, student understanding, and principles of equity, diversity, and inclusion. This call encourages anyone in the astronomy education community to actively collaborate with their NAECs[1] and submit proposals for financial support up to €2000 to organise and run a teacher training and professional development workshop in 2025 or early 2026. The team will work together to create and conduct a teacher training workshop tailored to their specific preferences, which will empower teachers with the knowledge and skills to teach astronomy confidently in their classrooms. In 2024, the OAE proudly supported 21 TTP workshops in primary, middle, and high schools worldwide. The OAE would like to thank the OAE Center Italy, OAE Center India, and the African Astronomical Society (AfAS) for their dedicated funding support for primary school astronomy teacher training, TTPs in the Indian region, and TTPs on the African continent, respectively. Proposals should be submitted via the online application form by 30 April 2025. Any inquiries about the programme or application process can be sent by email to ttp@astro4edu.org. The OAE would like to take this opportunity to congratulate the following countries, their NAECs, and respective teams that received TTP grants in 2024: **Primary schools** * Albania (Mirjeta Domi, Eglantina Teta & Sila Doko), * Indonesia (Premana W. Premadi, Novita Hudyaningtyas & Yatny Yulianty), * Lebanon (Jean-Pierre Saghbini, Marc Bou Zeid & Ahmad Chaalan), * Malaysia (Hasan Abu Kassim, Nurul Syahirah Binti Nazarudin, Norhasliza Yusof & Nazhatulshima Ahmad), * South Africa (Sibuyile Manxoyi, Buzani Khumalo, Sinenhlanhla Sikhosana & Senamise Sosibo), * Uganda (Doreen Agaba, Moses Todo & Bosco Oruru), * Türkiye (Ayşegül Yelkenci, Özcan Köse & Yağmur Karan), * Armenia (Sona Farmanyan, Lilit Hovhannisyan & Areg Mickaelian), * India (Niruj Mohan Ramanujam, Uma Subramaniyan, Cinthia Chandharasekaran, Jaya Paul Swamidass & Mekala Dhanasekaran). **Middle Schools** * Azerbaijan (Famil Mustafa, Khidir Mikayilov & Faik Nagiyev), * Dominican Republic (Breezy Ocaña Flaquer, Manuel Marcano, Omar Pérez Veloz & Erika Montero), * Egypt (Magda Moheb El-dine, Hagar M. M. Ghonaim, Hossam El din Mahmoud, Mohamed Farouk, Raouf H. H. Mabrouk), * Mozambique (​​Thomson Mucavele, Dercia Nhantumbo & Francisco Macucule), * Nepal (Rabina Maharjan Rupa Manandhar & Laxman Dongol), * India 2 (Kuntal Misra, Virendra Yadav, Chitra Singh, Mila Mitra & Gautam Agawari). **High School** * Chile (Carla Hernández Silva, Fernanda Alarcón & Irma Fuentes Morales), * Gabon (ESSONE OBAME Hans, OYANE NDONG Nova Audrey & OKOUMA Patrice), * Ghana (Albert Kuntu Forson, Sarah Boamah, Naomi Asabre Frimpong), * Mauritius (Nadeem Oozeer, Roddy Lollchund & Albert Forson), * Tanzania (Elineema Nassari, Hamuli Majeshi, Mponda Malozo & Kai Staats), * Togo (ADDOR Doh Koffi, AGBEKO Akouvi & Rosa Maria Ros Ferré). ## Notes [1] Collaboration with a NAEC team member is a prerequisite for submitting proposals. Teachers and/or astronomers interested in leading a workshop are encouraged to connect with a NAEC in their country for potential collaboration: https://www.astro4edu.org/naec-network/. NAECs have representation in approximately 110 countries worldwide. ## More information The IAU is the international astronomical organisation that brings together more than 12 000 active professional astronomers from more than 100 countries worldwide. Its mission is to promote and safeguard astronomy in all its aspects, including research, communication, education and development, through international cooperation. The IAU also serves as the internationally recognised authority for assigning designations to celestial bodies and the surface features on them. Founded in 1919, the IAU is the world's largest professional body for astronomers. The IAU Office of Astronomy for Education is hosted at Haus der Astronomie (HdA), managed by the Max Planck Institute for Astronomy. The OAE’s mission is to support and coordinate astronomy education by astronomy researchers and educators, aimed at primary or secondary schools worldwide. HdA’s hosting the OAE was made possible through the support of the German foundations the Klaus Tschira Foundation and the Carl Zeiss Foundation.

Last week twenty member states of the United Nations Committee on the Peaceful Uses of Outer Space (UN COPUOS) — the top UN body for civilian space-related matters — took the floor during discussions on the agenda item on dark and quiet skies, demonstrating its growing importance. The discussion included remarks on the need to find balanced solutions, the urgent need for nations to support research on mitigations, considerations on the cultural heritage of the night sky, and the importance of space sustainability discussions within international bodies. In attendance were members of the IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS), which is co-hosted by NSF NOIRLab and the SKAO. _“This week marked a significant moment for the future safeguarding of the science of astronomy,”_ said Piero Benvenuti, Head of the IAU delegation at COPUOS and Director of the IAU CPS. _“Never before have diplomats and the governments they represent spent so much time discussing the impact of growing numbers of satellites on astronomy. Their interventions were in many cases specific and committed to finding compromises so that technological development and scientific discovery can coexist.”_ _“It is essential that we find a balanced approach that embraces technological progress while safeguarding our dark and quiet skies. I firmly believe that UN COPUOS will greatly benefit from these discussions,”_ added Mila Francisco, Chilean Representative at the UN in Vienna. Securing an agenda item at the subcommittee is a significant success for the astronomy community, and the culmination of many years of coordinated action by astronomers to have the issue discussed at the highest international level. The Scientific and Technical Subcommittee of UN COPUOS will discuss “Dark and Quiet Skies, astronomy and large constellations: addressing emerging issues and challenges” annually until 2029. The subcommittee meets for two weeks and has representatives from 104 countries and 51 observer organisations, including the IAU and SKAO, as well as CPS member organisations the European Southern Observatory and European Astronomical Society, and representatives from industry also invited by delegations to contribute. A paper co-signed by 10 country delegations and seven observer organisations represented in the Group of Friends of the Dark and Quiet Sky for Science and Society, details collaborative efforts which are underway to mitigate the impacts of satellites on astronomy, including the development of a worldwide database of radio quiet zones. The paper also provides actionable recommendations for COPUOS member states to advance the protection of dark and quiet skies, including supporting the development of designs and materials which can reduce satellites’ impact, and supporting research to understand the effects on all stakeholders, both professional and non-professional. The paper’s recommendations are largely aligned with those developed by the IAU CPS. As the issue of Dark and Quiet Sky is relevant to that of space debris, similar recommendations have been included in the Zero debris technical booklet, recently published by the European Space Agency (ESA). ## More information The IAU is the international astronomical organization that brings together more than 12,000 active professional astronomers from more than 100 countries worldwide. Its mission is to promote and safeguard astronomy in all its aspects, including research, communication, education and development, through international cooperation. The IAU also serves as the internationally recognised authority for assigning designations to celestial bodies and the surface features on them. Founded in 1919, the IAU is the world's largest professional body for astronomers. The International Astronomical Union’s Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS) is a global organization co-hosted by the US-based NSF’s NOIRLab and the SKA Observatory (SKAO), under the auspices of the IAU. The CPS facilitates global coordination of efforts by the astronomical community in concert with observatories, space agencies, industry, regulators and other sectors to help mitigate the negative consequences of satellite constellations on astronomy. NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community. The SKAO, formally known as the SKA Observatory, is an inter-governmental organisation composed of Member States from five continents. Its mission is to build and operate cutting-edge radio telescopes to transform our understanding of the Universe, and deliver benefits to society through global collaboration and innovation. Headquartered in the UK, its two telescope arrays will be constructed in Australia and South Africa and be the two most advanced radio telescope networks on Earth. Through the development of innovative technologies and its contribution to addressing societal challenges, the SKAO will play its part to address the United Nations’ Sustainable Development Goals and deliver significant benefits across its membership and beyond. The SKAO recognises and acknowledges the Indigenous peoples and cultures that have traditionally lived on the lands on which the SKAO facilities are located.