Office for Astronomy Outreach

Dark and Quiet Skies

Dark and Quiet Skies


Dark and Quiet Skies is a global theme that raises awareness about the urgent need to preserve our night skies, both dark and quiet. While these two elements are closely connected, they represent different challenges.

Protecting dark skies means reducing artificial light at night across the electromagnetic spectrum through public policy, legal frameworks, community activism, and education. More recently, dark sky protection has also included the protection of the night sky from optical and infrared impacts (such as trails seen in images) resulting from the growing number of satellites in Low Earth Orbit.

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Gallery Dark and Quiet Skies

In this image, taken by ESO Photo Ambassador Yuri Beletsky, the control building at the Paranal Observatory can be seen below a rising Milky Way, like the proverbial pot of gold at the end of a celestial rainbow.
Starlink Generation 2 satellites constellation Credit: ESO
The soft glow of the Milky Way pours down like a waterfall over the VLT Survey Telescope (VST) at ESO’s Paranal Observatory. 2635 metres above sea level, the VST has an unparallelled view of the magnificently clear skies above Chile’s Atacama Desert. It is the largest telescope in the world dedicated to observational surveys in visible light, and it contributes to a vast range of studies, from discovering remote Solar System bodies to searching for exoplanet transits, to studying the structure and evolution of our galax.
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Main focus

By preserving our quiet skies, we guard against the negative impact of satellite constellations on ground-based optical and radio astronomy. This is the main focus of our partner, the IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS).


Through this initiative, we invite everyone to learn about the cultural, environmental, and scientific importance of dark and quiet skies—not only for astronomy, but for human well-being and the health of ecosystems.

This image illustrates the Bortle scale, which measures the impact of light pollution on the dark skies at a given location. It shows, from left to right, the increase in the number of stars visible in excellent dark sky conditions compared with cities
This image illustrates the Bortle scale, which measures the impact of light pollution on the dark skies at a given location. Credit: ESO/P. Horálek, M. Wallner

Panel Discussion

Protecting Our Dark Skies – Involving policy makers in the defence of the night sky

This event is the first in a series of discussions focused on engaging with policymakers to protect the night sky. Bringing together experts in astronomy, environmental policy, and public advocacy, the panel will explore how dark and quiet skies can be preserved through effective, collaborative action. As light pollution and satellite interference continue to increase, this conversation aims to highlight the cultural, ecological, and scientific value of the night—and the policy solutions that can safeguard it for future generations.

Join us in protecting the night sky for science, for nature, and for future generations.

Banishing light pollution. Credit:ESO/P. Horálek

Plan your own Dark and Quiet skies event

  • Planning your own event on light pollution abatement and dark sky protection?
  • Download our set of graphics
  • Maybe you’re planning a star party for the people in your neighbourhood or a mobile planetarium show with a local astronomy club.
  • Whatever your plans are, share them with us in our Events Calendar and become a part of the OAO community!
  • Register your event and be part of our international astronomy community.
ALMA antennas. Credit: ESO/José Francisco Salgado (josefrancisco.org)
ALMA antennas. Credit: ESO/José Francisco Salgado (josefrancisco.org)

International events: Global Light Pollution Initiatives Survey

We are gathering information about how countries around the world approach the fight against light pollution. In this survey, we ask you to provide some brief information about initiatives happening in your country (either led by you or someone else) and provide practical ways people can get involved in this effort.

This could include changing their light bulbs to warm LEDs, signing a petition, participating in a town hall, or joining a lobbying group -- whatever you think would be most relevant for your community.

We will use this information as part of a global resource on light pollution and as a way to promote global initiatives to protect our dark and quiet skies.

International events: International Dark Sky Week

The IAU OAO is an outreach partner with the International Dark Sky Week. The week is hosted by DarkSky International to help raise awareness about the light pollution’s many negative effects.

Program: Globe@Night Citizen Science Campaign

The IAU OAO proudly endorses the monthly Globe@Night citizen science campaign. This project gathers data from volunteer observers to track the impact of light pollution over time. Everyone is encouraged to contribute to this campaign. All you need is your eyes and an internet connection.

Start and end dates for each monthly observing period will be shared on the IAU OAO Facebook.

Program: Globe at Night - Sky Brightness Monitoring Network (GaN-MN)

Globe at Night - Sky Brightness Monitoring Network (GaN-MN) is a special project that extends the Globe at Night project through a global network of commercially-available sky-brightness meters for long-term monitoring of light pollution. The project is conducted in partnership with the University of Hong Kong.

More Information

All events must respect the general guidelines of the IAU Global Project and Themes, which promote the key role of astronomy for the betterment of science and society through collaboration and with a spirit of respect, tolerance, and peace.

If you need to change your events already on the calendar, please email the IAU Office for Astronomy Outreach Team via public@...Click to show with the subject line “Dark and Quiet Skies Calendar 2026 - Update”.If you cannot submit through this form, please email the IAU Office for Astronomy Outreach team via public@...Click to show with the subject line “Dark and Quiet Skies Calendar 2026 - Update”.