(urth) Green Is Urth Redux

[DAVID STOCKHOFF]

--- On Wed, 1/12/11, Lee Berman <severiansola at hotmail.com> wrote:

> From: Lee Berman <severiansola at hotmail.com>
> Subject: (urth) Green Is Urth Redux
> To: urth at lists.urth.net
> Date: Wednesday, January 12, 2011, 12:12 PM
> 
> >David Stockhoff- Incidentally, does anyone see any
> problems with the Moon getting either not enough or too much
> sun for photosynthesis? 
>  
> Surely. If the simple stripping of earth's thin ozone layer
> might play havoc with plant growth, the absence of an 
> entire atmosphere would make things much more difficult.
> Plants are not green by accident. That color provides
> maximum efficiency of energy utilization for the light that
> reaches earth through an atmosphere. The fact that
> Lune's plants are green suggests either that Lune has an
> earth-like atmosphere or that it has mechanisms to 
> artificially ensure that the light which hits the plants on
> Lune is roughly identical to the light that hits 
> Urth (or earth). 

Correct.

> (we are told that the greenness of Urth plants is not the
> same greenness as for Earth plants; in truth a red sun
> probably would not produce enough of the proper energy on
> Urth to allow the diet that Severian eats. He probably
> would be restricted to eating fungi, deep-water algae,
> maybe lichens or other low-intensity light utilizing
> plants. Casual meat-eating would be an insane luxury under
> such conditions).    

This phenomenon may not be susceptible to analysis, because you're right that a truly red sun would starve Earth if it doesn't swallow it. Of course, we don't know exactly how red "red" is---all we know is that it's red enough to make winters worse and crops suffer but not enough to force Severian to eat fungi for breakfast. Technically, it must be pink, or else it's something we can't get too precise about.