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Call to action: join us in measuring darkness by counting stars!

09 January 2026
Starry skies

The Milky Way is becoming less visible in the Netherlands. There is more and more artificial light. Too much light is bad for nature and humans. But how dark is it really? The University of Groningen has a darkness monitoring network, ‘but we can’t measure everywhere,’ says ‘darkness guardian’ Theo Jurriens. The public can therefore help during the national star counting campaign.

When

The measurements must take place between 16 and 28 January and between 15 and 27 February. This has everything to do with the position of the moon: measurements are taken when the moon is below the horizon. When it is cloudy, bad weather, or the moon is above the horizon, the measurements are meaningless.

How can you participate?

The constellation Orion is central to the measurement campaign. Anyone can participate in the measurement campaign by counting the stars in this easily recognizable constellation. The step-by-step plan is as follows: go outside (after 8 p.m.) and find the constellation Orion. Wait fifteen minutes for your eyes to adjust to the dark. The four corner stars of Orion form a rectangle: count the number of stars within this rectangle. Are you a stickler for accuracy? Then do the count several times in a row and report the average value. You can submit your measurements via teldesterren.nl, where the measurement data will also be visible on the map. This website also contains a manual with more information.

Awareness

Darkness, the oldest universal heritage, belongs to all of us and is important everywhere. With this measurement campaign, we hope to make people aware of the urgency of protecting darkness. Perhaps this will encourage you to look at the starry sky more often, and you will soon be able to find many constellations. This year, the star count is also a nice prelude to the National Stargazing Days: 27 February to 1 March. Telescopes will be set up in many places in the Netherlands, providing a wonderful opportunity to enjoy the starry sky.

Night watchers

Would you like to do more to promote a dark environment? Then join the night watchers network of the Nacht van de Nacht, a project of the Nature and Environment Federations to reduce light pollution. Night watchers are people who work at the local level to reduce light pollution by raising awareness, sharing knowledge, and organizing actions to dim or extinguish unnecessary (artificial) light.

Last modified:08 January 2026 3.01 p.m.
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