By changing the lights on different nights, it let us extrapolate to find out how bright the city would be if it turned off all the streetlights completely.
The result was surprising: if all the streetlights were turned off completely, Tucson would barely change in the satellite image. After midnight, only about 13% of the light from Tucson that's seen from space comes from streetlights.
(4/)
There was a difference between suburbs and the city center - streetlights made up a bigger portion of the light emissions from the outlying areas, but still only up to about a third of the total light.
(5/)
So the question remains: when we look at cities from space at night, if it's not streetlights that make up all the light we see, then what the heck is it? (6/)
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-B眉HNE: 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
(7/)
An extra special aspect of both apps is that they were co-designed with our teams of citizen scientists.
That means that from the very start, we had a team that helped us to design the entire app and project.
COVID hit in the midst of our starting up period, and since then we've been having meetings with the co-design team roughly every two weeks (94 in total).
(8/)
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.).
(9/)
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