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 have therefore developed an app to count light sources along street segments – from illuminated windows and advertising signs to street lamps and traffic lights.

Call for action!

As a part of Science Year 2023 – Our Universe, we are inviting you to count lights again this fall! A twist this year is that in addition to large counting campaigns, it will be possible to take part by surveying a single street!

Starting from September 1, you are invited to create a record of lighting using the Nightlights App. For our special “Time of Night” campaign this year, we want to find out how the distribution and use of lights changes during the course of the evening and night. For example, how many businesses turn off their signs late at night, and how does this vary with geography? To do this, we need people to survey one or more streets at least twice with at least an hour between the survey. It’s easy to do so with the Nightlights app, where you select an existing street section or create one yourself. The more streets you survey, and the more often you survey them, the better we will understand the times and kinds of lights that turn off. We are also looking for partners to organize and run larger local campaigns. If that sounds like something you would enjoy, please contact us!

How to participate

Once you have successfully completed the Online Tutorial, you will know everything you need to know about the different shapes of lights and how to count them in the app. Then you just have to install the Nightlights App on your phone, choose a transect and off you go! Detailed information will follow, so please check back for the final information this fall. If a lot of people help to collect data, we could provide valuable information to the Bundestag and local mayors and chambers of commerce regarding lighting and energy practice in Germany. If you live in another country, feel free to use Nightlights App as well.

How to learn more

From May to September, the roadshow Universe on Tour will travel to 15 cities in Germany. Here, you can learn more about the importance of light as an information carrier and the effects of light pollution on the environment, the population and astronomy. Each Saturday at 8 pm, we take you on a Light Walk in the city where the roadshow is that week (meeting point: in front of the exhibition tent). Note: in case of bad weather the Light Walk is cancelled.

The previous Nightlights campaigns - in Germany and worldwide

From the end of August 2021 until mid-November 2021, more than 200 citizen scientists 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 many 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, as well as places outside Germany, including Canada, France, Indonesia, Italy, Ireland, Kenya, Serbia, Spain, Turkey and the USA.

The project participants are now involved in the evaluation and interpretation of the first data and in the work on scientific publications.

Goals of the Nightlights campaigns

  • We aim to understand how the different sources of light emissions contribute to the light emissions observed by satellites. For this reason, we want to understand how lighting early in the evening relates to light late at night (when the VIIRS DNB satellite instruments pass overhead).
  • We aim to investigate and document local differences in the numbers and types of lighting in different places. For example, we are comparing city centers to residential neighborhoods, and campaign communities to one another.
  • We aim to 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.

The Nightlights team meets regularly online. If you want to stay up to date about our activities, subscribe to our mailing list or register in the Nightlights App to count lights on your own. To help you get started, here is a short app introduction (video). If you have questions about using the app, our answers to “frequently asked questions” will usually help.

Contact us if you want to help organize a local campaign: nachtlichter@gfz-potsdam.de

Thanks for your interest in our project!

Christopher Kyba and Loeka Jongejans