Thread by @AndreasJechow

About a year ago we had the 1st #covidlockdown in Germany

I'm the stay-home homeschooling dad - my wife is a medical doctor

But I could work @ night which I do often anyway

I did measure the night sky brightness and found it had decreased compared to before lockdown (1/12)

https://twitter.com/AndreasJechow/status/1320724549344833537

so in March 2017 it was less bright than in 2020 (see figure for zenith brightness)

this is surprising because we would expect light emission and #lightpollution to increase like shown in the paper we co-authored with @skyglowberlin and others

advances.sciencemag.org/content/3/11/e…

(2/12)

using night-time light satellite time series data (VIIRS DNB) we saw an increase in most major towns along the route we measured

you can check such data with @skyglowberlin tool:

lighttrends.lightpollutionmap.info

this was what we eexpected (3/12)

however, we saw a decrease in #skyglow #lightpollution using all-sky cameras

how is that possible? (4/12)

well we strongly believe that it is due to reduced air traffic mainly and other reduced light emissions that the satellite cannot pick up

a group @DLR_de showed that there are less contrials when air traffic reduces so drastically as in #lockdown

dlr.de/content/en/art… (5/12)

airport statistical data showed that air traffic in #berlin decreased remarkably in March 2020 (−46.5%) compared to March 2019

April 2020 almost no air traffic was present compared to April 2019 (−93.2%).

(6/12)

our results are backed up by findings by @pmisson @cefalopodo @jon_bennie @KevinJGaston and others which draw a similar conclusion

(although they cite our work in a special way... 😉)

mdpi.com/2072-4292/13/2…

(7/12)

what does that mean?

do we need a #pandemic or a #lockdown to fight #lightpollution? Should all air trffic be banned?

Certainly NOT!

but #airpolluton goes hand in hand with star visibility (also in regions w/o #lightpollution)

because of reduced light scattering

(8/12)

this was shown by many papers like this one here for example:

academic.oup.com/mnras/article/…

(9/12)

so clean air goes hand in hand with better star visibility and reduced light pollution

and should become a part of the #darksky agenda

(10/12)

lets hope that despite this pandemic and those perpetual lockdowns are surely annoying us and making us sick

that we learn some things from this whole global crisis

(11/12)

and a big hail to all #womeninscience because I belong to a minority

mostly women suffer from childcare burden in this pandemic

"75% of women reported feeling stressed, compared with 59% of men."

see here

nature.com/articles/d4158…

(12/12)

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