this post was submitted on 28 Aug 2025
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For anyone who wants to know the real answer. Unfiltered sunlight is white in appearance covering the full visual light spectrum. Once this light hits the atmosphere higher frequencies such as violet and blue are scattered as the lower frequencies pass through making the sun appear yellow. Most of the light still makes it through the first pass however so most of the full spectrum still passes through is reflected again by the earths surface. Once this bounced light hits the atmosphere again on the underside the higher frequencies are again scattered letting lower frequencies pass making the sky appear blue. Of the light that hits the plants leaves green light is reflected while everything else is absorbed making the leaf appear green.
I don't think it's pure white. Given the type of our star I remember reading it's actually yellow with a hint of green.
It peaks in yellow/green, but its not a ton more yellow than the rest of the visible spectrum so its still very white, the yellow appearance from earth's surface is still more due to atmospheric filtering than the actual spectrum its emitting.
but WHY do plants reflect green light instead of any other color? you skipped the most important part!
Because the way chlorophyll is shaped at a molecular level, it acts like a filter. It lets red and blue light pass, but reflects green light.
You might be thinking, well wouldn't it it better to absorb green too? Why didn't chlorophyll evolve to absorb all colors, making plants black? The answer is because evolution don't give a damn about the best way to do things, only the good enough way. Chlorophyll developed by random chance, and blue-green algea (with chlorophyll) beat red algae (with phycoerythrin) to evolving into complex plant structures.
Some plants do have black leaves
And red leaves
Yeah, but not due to photosynthesizing pigments, afaik. Only other pigmentation in the leaf. Though it may still be an adaptive benefit.
Most of these are probably under growth. Much of the light gets filtered by the time it gets to them and they evolved to maximize the remainder.
Warmer leaf may increase photosynthesis rate
Sunlight is actually mostly green/blue, more green at the surface. It just appears white because that's what we're used to and the difference in intensity isn't that much for visible light anyways.
See https://seos-project.eu/earthspectra/images/Solar-spectrum.png
Rest checks out as far as I remember! Though the wording about the scattering is a bit loose. More specific details at https://en.wikipedia.org/wiki/Diffuse_sky_radiation