Christopher Kyba 🇨🇦🇩🇪🇪🇺

Heisenberg Professor for Nighttime Light Remote Sensing at the Institute of Geography of the Ruhr University Bochum

#RemoteSensing #CitizenScience #LightPollution

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Last Notes

2026-08-14 09:41:27 UTC

If you like #Astrophotography, check out the winners of this year's #DarkskyInternational photography contest! https://darksky.org/what-we-do/events/photo-contest/capture-the-dark-2026-winning-photographs/
Amazing!
Don't miss the #cat watching #fireflies!

2026-07-15 07:31:07 UTC

This is AWESOME! Cast members from different #StarTrek series make the case for reducing #LightPollution and preserving our ability to experience the stars from here on Earth: https://www.youtube.com/watch?v=Hc2zeKd-xf0
#DarkSkyInternational #StarTrek60
https://fediscience.org/system/media_attachments/files/116/922/817/349/507/159/original/a64ae69267174cbf.png

2026-06-19 19:31:38 UTC

Any astronomers looking for a wild new job?
I got a message from an ecologist in Belgium today, and he's looking for a postdoc with experience in photometry to work on analysis of all-sky imagery for an experiment on the impact of #LightPollution on birds.
This is not a job offer! He would work together with the candidate on an internal university grant.
If anyone is interested (PhD in #astronomy or closely related field required), send me a message.

2026-04-21 06:57:00 UTC

If you're reading this on Mastodon, there's a good chance that you're part of what conservatives call "the elite", and there's almost no chance that you're part of what liberals call "the elite".

2026-04-16 11:49:59 UTC

The @npub1pzv…xhlh is hiring: https://www.ecsa.ngo/2026/03/18/job-opportunity-ecsa-web-developer/
#FediHire
https://fediscience.org/system/media_attachments/files/116/414/228/290/534/916/original/d209c8de12ee971e.png

2026-04-02 09:10:00 UTC

RE: https://neuromatch.social/@jonny/116324676116121930
This thread is amazing. A data center is probably being built next to you as we speak (making noise, sealing the soil, raising your electricity price, and burning natural gas) because computer code written by "AI" is disastrously, shockingly, hilariously inefficient.
#note19wu…qvf2

2026-03-27 09:55:18 UTC

This is amazing: it turns out that at least one ant species has come up with a way to use the #moon as a compass - despite the fact that the moon's position in the sky and the time it appears changes dramatically night after night along with the phase.
🌘 🌗 🌓 🌒
Short commentary: https://doi.org/10.1016/j.cub.2026.02.008
Actual article: https://doi.org/10.1016/j.cub.2026.02.011
Calling all science #journalists, here's a good story tip!
https://fediscience.org/system/media_attachments/files/116/300/525/870/473/582/original/fe580a980cec6348.png

2026-03-05 06:26:02 UTC

I'd love for a journalist to ask the following question to one of the Prime Ministers, Chancellors, or Presidents who say they think what the US is doing is right (even if they don't want their country to join the war):
"If a civil war results from the bombings and elimination of leadership in Iran, how many Iranian refugees are you planning to welcome?"
#Iran #Refugees #Carney #Merz

2026-03-02 14:47:31 UTC

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Most people in brightly lit countries probably take for granted that clouds are bright at night, but this is completely unnatural. You can see it better in this pair of photos we published in a later paper (titled "Red is the new black"): https://doi.org/10.1111/j.1365-2966.2012.21559.x
This probably matters a great deal for nocturnal animals, because it's a reversal of an environmental condition that existed during the hundreds of millions of years that life evolved.
https://fediscience.org/system/media_attachments/files/116/160/116/033/379/171/original/c85c316850783314.png

2026-03-02 14:42:48 UTC

15 years ago, I co-authored my first paper in the field of #LightPollution studies: https://doi.org/10.1371/journal.pone.0017307
Up to that point, work on artificial brightening of the sky had been done almost entirely by astronomers, who (for obvious reasons) weren't really interested in cloudy nights. But because I was involved closely with ecologists from the Leibniz Institute of Freshwater Ecology and Inland Fisheries @npub1gdg…8rws, we realized that it's also important to measure the extent to which overcast and clear nights differ.
Through a bunch of twists and turns I now work on #RemoteSensing using nighttime light, but that was the paper that launched me into this direction.
https://fediscience.org/system/media_attachments/files/116/158/725/789/897/791/original/ec4acaa805e1c4de.png

2026-02-27 15:01:24 UTC

RE: https://eupolicy.social/@finnmyrstad/116141082378515849
I was at a lighting industry conference about a decade ago, and *two* speakers from the manufacturing sector said something equivalent to "we know the long life of LEDs is a problem for you. But don't worry, in a few years we will have worked it out so that LEDs will only last about five years. Not the actual diodes themselves, of course, those will be working fine. But we'll design the drivers to fail after about five years so that the lamp has to be replaced".
Time for @npub1m96…ag4y to tell industry: no more enshittification!
(Watch the video, it's fantastic)
#note1yew…x2t4

2026-02-10 20:58:43 UTC

This trip did NOT go according to plan...
https://fediscience.org/system/media_attachments/files/116/048/333/615/275/087/original/abb8a05b348bdaf1.jpg

2026-02-09 21:52:26 UTC

Has anyone else seen a huge increase in email spam in the last few months? My academic email address is getting so many more "here's your bill" scams than I used to.

2025-10-24 18:57:52 UTC

A colleague of mine is offering a funded PhD position (4 years) in #Metrology of #Skyglow in Switzerland: https://live.solique.ch/metas/de/internet/jobs/PhD-Position-in-Metrology-for-Skyglow-Measurement-and-Monitoring-(4-years-%E2%80%93-100-)--3891747/
And at the same time I'm offering a PhD on #RemoteSensing using nighttime lights: https://jobs.ruhr-uni-bochum.de/jobposting/62065e5be70a916f65edd647cd1b1740b04cd72e0
It's great to see #LightPollution and #Night research being taken seriously by funding agencies!
#AcademicJobs #PhysicsJobs #GeographyJobs #fedihired #getFedihired

2025-10-12 09:11:08 UTC

This doesn't seem to be in the major newspapers yet, but it seems like it should be: someone made a massive leveraged bet short on bitcoin and etherium 20 minutes before Trump's China tariff announcement on Friday, and walked away with $70 million: https://www.rawstory.com/trump-2674176395/
#crypto is such a mess.

2025-09-12 07:22:46 UTC

Photogrammetry and #RemoteSensing job at TU Graz: https://jobs.tugraz.at/en/jobs/5eb41c80-4df1-3acf-4c38-688b183ca4a8?preview=true
#AcademicJobs
https://fediscience.org/system/media_attachments/files/115/190/118/539/090/589/original/7b09f80e208a572c.png

2025-06-26 10:13:11 UTC

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Thanks for sharing that! I agree with the 😬, it's astounding the extent to which people in EO simply do not talk about this.

2025-06-26 09:17:09 UTC

It's a bit surreal to be in this #LPS25 panel discussion about the future of small sats and constellations, and no one talks at all about the fact that LEO is already on the way to runaway debris at the present number of space objects. http://www.researchgate.net/publication/391093502_CRITICAL_NUMBER_OF_SPACECRAFT_IN_LOW_EARTH_ORBIT_A_NEW_ASSESSMENT_OF_THE_STABILITY_OF_THE_ORBITAL_DEBRIS_ENVIRONMENT
https://fediscience.org/system/media_attachments/files/114/748/903/516/857/367/original/4a26afeb08739384.png

2025-06-16 09:21:23 UTC

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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/)

2025-06-16 09:20:35 UTC

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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/)
https://fediscience.org/system/media_attachments/files/114/692/293/466/728/913/original/435b25b2beb2380c.jpg

2025-06-16 09:17:01 UTC

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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/)
https://fediscience.org/system/media_attachments/files/114/692/278/410/265/977/original/d0a56aae5ebe749b.jpg

2025-06-16 09:12:18 UTC

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That question from the journalists had a major impact on my research career, and I’ve spent several years trying to understand the amount that different types of light sources radiate into the night environment.
That led to an EXTREMELY COOL research paper: https://doi.org/10.1177/1477153520958463
The city of Tucson, Arizona alternatively dimmed and brightened nearly their entire street light network (tens of thousands of lights!), in order to see how much light comes from the streetlights, and how much comes from other lights.
(3/)
https://fediscience.org/system/media_attachments/files/114/692/265/054/727/863/original/72fe7d842dfe1efa.jpg
https://fediscience.org/system/media_attachments/files/114/692/265/055/193/211/original/1f8622c9904d0608.jpg

2025-06-16 09:06:29 UTC

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First off, some background. In 2017, I published a paper that showed that most countries in the world are getting brighter at night in nighttime satellite observations: https://doi.org/10.1126/sciadv.1701528
A number of journalists who reported on that paper asked me “what is actually changing on the ground?” Are streetlights getting more numerous or brighter? Or is it because bike paths are getting lit up now? (seriously got that question from multiple journalists…) Or is some other kind of light changing?
I realized that not only did I not know the answer, but that no one even knows how much the different light types contribute to the brightness of the ground (as seen from space), or the brightness of the night sky (as seen from the ground).
(2/)
https://fediscience.org/system/media_attachments/files/114/692/241/552/883/807/original/6c5e335070282118.jpg

2025-06-16 09:03:59 UTC

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 👇
(1/)
#CitizenScience #LightPollution #OpenAccess #NighttimeLights #RemoteSensing #Nachtlichter
https://fediscience.org/system/media_attachments/files/114/692/232/646/474/518/original/6af600bfdd2eed66.jpeg

2025-06-07 20:29:02 UTC

"Information" from #ChatGPT when prompted to explain why Berlin is brighter than Chicago in one browser window, compared to when promoted to explain why Chicago is brighter than Berlin in a different browser's window.
This is why I hate when journalists write about "hallucination".
Every single text it generates is just a made up plausible combination of letters. It's just a variant of the idea of a thousand monkeys typing on a thousand typewriters that's more efficient than the monkeys at generating plausible text.
https://fediscience.org/system/media_attachments/files/114/643/959/234/905/191/original/c6a0e6defe29b589.png
https://fediscience.org/system/media_attachments/files/114/643/962/526/579/493/original/19344f5d0ebd2977.png

2025-04-11 14:10:18 UTC

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👍

2025-04-11 07:44:47 UTC

The European Citizen Science Association has created a Mastodon account (@npub1pzv…xhlh), but they have haven't posted yet.
They just announced at the annual general membership meeting that they are planning on starting to post to Mastodon soon.
If you are interested in #CitizenScience and want to encourage them to post more here (and less on for-profit platforms like Bluesky), please follow them 😃

2025-04-10 19:20:22 UTC

Talking with my Dad today about traveling to the US, he told me a story about another Canadian (two degrees of separation, a colleague of someone I know well). She works in finance in New York City. She recently went back to Canada for a short visit, and then when she tried to return, US immigration decided not to let her back in. That's it. No way to appeal. Now she has an apartment and job in NYC, but is working from Canada, and the company lawyers say there's nothing they can do.
I really cannot imagine traveling to the US at this point.

2025-03-05 09:17:03 UTC

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This is my favorite photo for demonstrating the impact of #LightPollution on physiology. The image was taken by shows a soybean field illuminated by a badly directed streetlight.
What's happening here is that soybeans are supposed to grow leaves in the early part of summer, and as nights get longer, they should make #soybeans and turn brown. In the green area, the plants don't understand what time of year it is, and it's therefore a complete loss for the farmer.
The reason I love the photo so much is because you can see the shadow of the light mast on the field.
The photo was taken by Dwaine Eddie McGriff & Ben Tankersley, and originally posted to Xitter (the post no longer exists).
The problem could be entirely solved by using a streetlight with strong backlight shielding (i.e. shining the light only on the roadway).
https://fediscience.org/system/media_attachments/files/114/109/044/724/076/856/original/43562ce6ddabc880.png

2025-03-05 09:09:51 UTC

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But does shining a bit of light really change behavior? And what about physiology?
Well, changes in behavior are simple to demonstrate: the whole reason we use artificial light at all is to allow us to see better at night, in order to enjoy ourselves and enable the nighttime economy.
Just as light allows people to get around and stay up later, animals can also use it for the same purpose. This can be beneficial or detrimental, depending on the animal. But it's clearly a huge change compared to their evolutionary experience.
https://fediscience.org/system/media_attachments/files/114/109/032/054/783/351/original/8d6d825fc3b0f516.png

2025-03-05 09:04:05 UTC

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Before getting to skyglow, let's just quickly remind ourselves that light at night is one of the most dramatic environmental changes that humans have made to the Earth. Over many parts of the Earth, true night no longer occurs, we experience only twilight or daytime.
The image shows the brightness of skyglow around the world: https://www.science.org/doi/full/10.1126/sciadv.1600377
For every place colored yellow, the sky directly above on a starry night is at least twice as bright as natural.
https://fediscience.org/system/media_attachments/files/114/109/011/227/586/912/original/d342184d57ab014a.png

2025-03-05 08:59:43 UTC

We know that when artificial light shines directly from a light source onto living things at night, it affects their behavior and physiology. But what about the diffuse glow of the night sky, does that affect the environment?
Turns out it does. Read more in this brief thread 🧵
#Skyglow image by [@andreas_jechow](https://vis.social/@andreas_jechow )
#LightPollution #Ecology #Pollution
https://fediscience.org/system/media_attachments/files/114/108/989/134/214/618/original/8079dba8e3f5c1c0.jpg

2025-02-14 10:44:32 UTC

TCrB, TCrB, TCrB!
Too bad it's cloudy...
#Astronomy #TCrB

2025-02-03 13:15:37 UTC

New #Introduction at Fediscience:
I'm an environmental scientist with an interest in the night, and how we change it with artificial light.
I am Canadian and live in Germany. I most frequently post about science and #LightPollution.
In the photo below, the light was installed backwards, so that it shone on the flowers instead of the stairs for a decade 🤦‍♂️
https://fediscience.org/system/media_attachments/files/113/940/134/221/803/563/original/4871606701b05678.jpg