Street lamps, illuminated signs and buildings – lights at night improve safety and make cities more attractive, but have also been shown to have negative effects for humans and animals. The more light there is, the fewer stars you can see in the night sky. How many stars can you see where you live? In this year’s mass experiment, people from all across Sweden can help scientists measure light pollution by counting stars in the sky.

Our use of artificial light has dramatically changed the environment in large parts of the world. Scientific studies have shown unexpected and worrying effects on the biology of many organisms as well as on whole ecosystems, but also on human health. The problems of artificial light are commonly referred to as light pollution.

In the Star-Spotting Experiment, thousands of pupils, members of outdoor associations, other clubs and members of the public in Sweden and other European countries are being given the opportunity to contribute to scientific research about light pollution. The project will also create important knowledge about ecology, sustainability and urban planning.

The citizen science project started in February 2019 and run to the end of February 2020 and the app will be available to use throughout this time period. The researcher responsible for this year’s experiment is Urban Eriksson, a researcher and senior lecturer in physics with a focus on astronomy education at Lund University and Kristianstad University.

Urban Eriksson, Lunds universitet och Högskolan i Kristianstad. Foto: Lunds universitet

How it works:

You will need:

  • A cardboard tube (e.g. a kitchen paper roll), a bit of string, tape and a protractor to make your measuring tube and a compass.
  • Download the app ”The Star-Spotting Experiment”/”Stjärnförsöket” to your mobile or tablet.
  • Go out at least one hour after sunset and wait for ten minutes to get your eyes used to the darkness. Then point the tube in nine different directions in the sky and count how many stars you can see through the tube. Report this in the app along with information about the day, time, location, weather etc.

You are welcome to go out and do this this several times.

Illustration: Lotta Tomasson/VA
CC BY-NC 2.0

For teachers

The Star-Spotting Experiment covers a range of curriculum subjects and can be used with both primary and secondary classes as well as for adult education courses. A teacher’s guide and detailed tutorial is available (available only in Swedish at the moment). Before, during and after the experiment, pupils and teachers will have the opportunity to interact with participating researchers and each other via a dedicated Facebook group.

Other countries

At the moment the app can only be used for observations in Sweden. We are keen to involve other countries in the experiment, which will allow for international comparisons. Please get in touch with us if your organisation would like to co-ordinate the Star-Spotting Experiment in your country during September 2019 – February 2020.

More information: The Star-Spotting Experiment (pdf).


  • February 2019: Project start in Sweden. The app available for download, publication of instructions, teachers’ guide and instruction videos in Swedish.
  • September 2019 – February 2020: The Star-Spotting Experiment runs in countries across Europe. On European Researchers’ Night (27-28 September 2019) the results from the data collected during early spring will be published.
  • Spring 2020: Publication of results.

For further information and to register your interest in participating:

Contact project managers: [email protected]

For more information in Swedish, visit the Swedish page.

Instructional films

Press ”CC” to turn on English subtitles.


The 2019 mass experiment is a collaboration between VA (Public & Science) and Kristianstad University, Lund University, the National Resource Center for Physics Education (NRCF), the Swedish National Space AgencyThe Swedish Astronomical Society and the two science centres House of Science (Vetenskapens hus) in Stockholm and Umevatoriet in Umeå. It is financed by Formas, the Swedish National Space Agency and European Researchers’ Night via the EU’s research and innovation programme Horizon 2020, GA 818421.

The international project is run in collaboration with Fundación Descubre, Esciencia and La Palma Centre in Spain and University College Cork and Trinity College in Ireland.