This comment reminded me that I once read something about an Earth observation satellite that has a sophisticated optical system (possibly a camera) that it tuned to a very narrow range of wavelengths where the Sun's spectrum is particularly dark and the chemical process of photosynthesis happens...

I've just posted the question Which spacecraft can see plants "glow" during photosynthesis during the day, and what wavelength does it use? in a different SE site. I can't remember the details of which spacecraft this was or how exactly it worked. My question here is simply about light produced ...