Wednesday, July 1, 2020

Changes in light emissions during the COVID-19 shutdowns

At the start of the lockdown periods in Europe and North America, a few people speculated about what it might mean for changes in light emissions. I was skeptical that we would see much of anything.



Shortly afterwards, NASA showed some results for Hubei province in China:




We are still waiting for the monthly satellite data composites for February-April to come out, but I still don't expect to see much in most places. However, it turns out that there were some pretty dramatic changes in at least a few places around the world. The best example I've seen of this comes from Poland. Check out these two photos of Kraków, Poland, that Mateusz Windak posted on a Polish forum:

This work by Mateusz Windak is licensed under a Creative Commons Attribution 4.0 International License.
Click for the full size version.

Here's what Mateusz had to say about the photos:

The animation shows differences before and after midnight, when the Cracow city lights are switched off. After the switch off, only private light sources and the highway in the foreground remained. The lights were turned off for a month and a half from 00:00 to 04:00 each night due to the lack of traffic during the lockdown period of the COVID-19 pandemic. Currently, Cracow has stopped shutting down the lights, but some other cities are still continuing this practice.
The photos were taken from Wieliczka, a neighboring city, using a Mavic Air drone. They are four panel panoramas, the settings for each photograph are: 2s, ISO1600, f/2.8.


Thanks for sharing your photos Mateusz! I find it really impressive that in addition to the lights going off, you can also see the decrease in sky brightness

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