We count lights, because the night counts

Satellite images of the earth at night show a worldwide increase in nocturnal light emissions and light pollution, including in Germany. Unfortunately, we don’t presently know what types of lights (e.g. streetlights, advertising) are driving this increase, or for that matter, how many of each different type of light there are. Our group of citizen scientists and researchers at GFZ have therefore developed an app to count light sources along street segments – from illuminated windows and advertising signs to street lamps and traffic lights.

The Nightlights campaigns – in Germany and worldwide

From the end of August 2021 until mid November 2021, more than 200 citizen scientists have counted and classified almost a quarter of a million artificial light sources in public streets and squares. While counting lights they have walked 645 kilometers and covered a total of 22 square km in different field sites in Germany and worldwide.

The data was collected in German cities and communities, notably in Achtenwehr, Berlin, Bochum, Borkheide, Dresden, Erlangen, Erfurt, Freising, Fulda, Herzogenaurach, Köln, Leipzig, Leverkusen, Potsdam, Preußisch-Oldendorf, Rosenheim, Trier, Wittenberg, Würzburg, and places outside Germany, including Canada, France, Indonesia, Italy, Irland, Serbia, Spain, Turkey and the USA.

The project participants are now involved in the evaluation of the data and in the work on scientific publications. The first results are expected from mid-2022. Together the nightlights network will also contribute to more awareness for sustainable lighting.

Goals of the Nightlights campaigns

We aim to understand how the different sources of light emissions contribute to the light emissions observed by satellite. For this reason, we are sampling lights over large areas, in order to be able to compare what we observe with what satellites see.

We will also investigate and document local differences in the numbers and types of lighting in different places. For example, we will compare city centers to residential neighborhoods, and campaign communities to oneanother.

We create awareness for the transition to sustainable lighting, by inviting citizens in different cities to use our app, participate in our nightlight measurement campaigns, and thus actively engage with artificial lighting and its side effects.

Although the 2021 Nightlights campaigns ended in November 2021, you can still use the app, if you like. The first step is to complete our tutorial, and then install the Nachtlichter app on your phone (it’s a progressive web app). If you’d just like to try it out, you can create your own street segment from within the app.

Key links and information when using the Nightlights app

If you have any problems or questions when using the Nachtlichter app, please watch our little youtube video in which we explain how to use the app. If you still have problems, see our answers to frequently asked questions and a number of issues that have happened with the app several times.

Thanks for your interest in our project!

Christopher Kyba and Nona Schulte-Römer