Nic oh n_lein! Nov 7, 2022
Christopher Kyba

The center of Cologne, Germany, imaged in 5 different wavelength bands: ultraviolet, visible (red, green, and blue), and infrared.

The differences between the photos come about because of the different lighting technologies. Orange high pressure sodium has a strong infrared signal, while white LED is only in the visible band.

I'm not sure yet what the UV emissions are, but they're probably from metal halide lamps.

Imaged during the #CALEC project funded by the City of Köln.

Nov 7, 2022 at 11:48amWeb
Show threadHuub EggenNov 7, 2022
@skyglowberlin Cool! Is there anything known about the strong infrared signal regarding night life (plants, animals)? Blue/white light is known to have an influence on the production of the melatonin hormone.
Show threadChristopher KybaNov 7, 2022

@huubeggen I don't know much about which animals are able to use NIR, other than to know that there certainly are some animals who can see further into that part of the spectrum than humans.

The reflectivity of plants goes way up in the NIR - plants don't do photosynthesis using NIR. Nevertheless, I wouldn't be willing to say that it certainly does nothing to any plants on Earth.

Show threadHuub EggenNov 7, 2022
@skyglowberlin Thanks for your reply. I was wondering after that recent paper in Science about light pollution in Europe as analysed from images taken by astronauts from #ISS.