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Comment by trhway | Hacker News Reader

Sun's radiation peak energy at sea level is around 500-600nm http://en.wikipedia.org/wiki/Sunlight#mediaviewer/File:Solar...

which is green

http://en.wikipedia.org/wiki/Light#mediaviewer/File:Linear_v...

That is why grass/trees are green - they consume only the edges of the spectrum (about 10-15% of the total sunlight coming through) bouncing the rest back.

With respect to the original point about orange being average color of Internet photos - keep in mind that most photos are produced by digital CCD cameras which are more sensitive to orange/red than green/blue.

http://www.gitthailand.com/image/ccd-spectrum.jpg

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Why does that explain why plants are generally green? If you had told me that the energy peak was at X wavelength, I would have guessed that plants absorbed most of that wavelength in order to not be wasteful rather than preferentially reflecting that wavelength.

>If you had told me that the energy peak was at X wavelength, I would have guessed that plants absorbed most of that wavelength in order to not be wasteful rather than preferentially reflecting that wavelength.

the plants consume edges of spectrum, so they would bounce the X wavelengths (green in case of our Earth) as it is just an unnecessary heat for them.

Plants are actually pretty miserably inefficient at turning sunlight into stored energy: http://en.wikipedia.org/wiki/Photosynthetic_efficiency (not only do they reflect away most of the light, but photosynthesis isn't linear at all graphed against light intensity: most of the noonday sun is wasted)

There's no real consensus on why. (There's some wild guessing that green photons might be too hot to handle: smashing fragile biomolecules apart rather than powering them... (http://scienceline.ucsb.edu/getkey.php?key=500) but then why does chlorophyll run fine on purple light?) You'd figure that there would be incredible selection pressure on increasing photosynthesis efficiency, but maybe they're stuck on a local maxima: it's not like a single mutation can turn a C3 plant into a C4 plant: http://en.wikipedia.org/wiki/C4_photosynthesis

Interesting. I guess it actually emits all sorts of frequencies of light visible or not, but Superman is still wrong. :)

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