The #Nachtlichter app was designed to assist participants in counting and classifying light sources. We pre-defined street segments (usually from one street corner to the next), and participants went there at night and reported all the different lights they could see.

One question that we had to deal with early on was "how do we categorize all the different light sources that are out there?" In the end, we came up with 18 categories (including "other" as the final category for uncommon things like flagpole lights, glowing park benches, illuminated water fountains, etc.).

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That's what motivated our #Nachtlichter project. In 2019, the @association issued a call to Helmholtz Centres for #CitizenScience projects. In addition to running a citizen science experiment, the projects had to involve at least two different centres.

Together with colleagues from @DLR and @ufz, we submitted a project idea called Nachtlicht-BüHNE: https://nachtlicht-buehne.de/

The name in English means: "Citizen Helmholtz network for research into nocturnal light phenomena".

The project had two parts: DLR (the German space agency) would create and app for reporting Fireballs: https://meteor.nachtlicht-buehne.de/

And our group would create an app for studying outdoor lights: https://lichter.nachtlicht-buehne.de/#l=14.7/49.57249/10.89506

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In 2021, hundreds of citizen scientists walked a distance of 600 km, counting up and classifying all of the outdoor lights they could see while they did it. The results of their observations have just been published in the journal Nature Cities: https://www.nature.com/articles/s44284-025-00239-5

Find out why they did it, and what they found out in this thread 👇

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#CitizenScience#LightPollution#OpenAccess#NighttimeLights #RemoteSensing #Nachtlichter