Re: Was the Gondwannan moon bright enough for plants to photsynthesis

Dear Sir:

Your question is really outside my area of expertise, but I will answer 
it as well as I can. 

Part of the answer is that most of Gondwanaland did not experience 6 months 
of darkness. That condition only holds quite close to the poles. 
Gondwanaland was large, and most of the continent never experienced 
multi-day darkness. I do not know exactly how bright the moon was when it 
was closer to the earth in the geologic past, nor exactly how much light 
plants need. However, my feeling is that even a much brighter moon would 
not have been sufficient to support photosynthesis. I believe that you 
could find out from a plant physiologist how much light plants need, and 
from an astronomer how bright the moon has been. These two facts would show 
whether my assessment is correct. Remember though that most plants absorb 
light at some wavelengths more readily than at others. Moonlight is 
probably not as useful as sunlight. If there was a time and place in which 
plants got by on reflected light from the moon I would expect an unusual 
flora. the Gondwana flora was lush and does not seem to me to show evidence 
of survival with limited light.

Best Regards,
David Kopaska-Merkel
Geological Survey of Alabama
PO Box 869999
Tuscaloosa AL 35486-6999
(205) 349-2852