[LMB] Chlorophyll

Karen Hunt huntkc at gmail.com
Sat Dec 25 17:18:38 GMT 2021

On Sat, Dec 25, 2021 at 12:05 PM WILLIAM A WENRICH <wawenri at msn.com> wrote:

> So are there chemicals/elements as or more common than magnesium that
> could be used?

On earth, not really. Elsewhere? We don't know enough. Best reference I can
give you:

> > The plants on Barrayar (on topic for once) are red and brown instead of
> > green (Ekaterin remarked that a green Barrayan plant would be very sick.)
> > because the plants use a different chemical. This appears to be a common
> SF
> > trope but do we know of any other chemicals that would work?
> > Also the sky on other planets is written to be just about any color. Pink
> > or butterscotch on Mars?
> >
> Sergyar's sky is apparently turquoise. Not sure what makes the greenish
> additions to the blue that comes from having an ozone layer.
> Some plants here on earth run to the reds - some just in fall, others also
> in spring and other times (thinking of Japanese maples). These plants have
> chlorophyll in the leaves, but also have lots of carotenoids.
> Now blood is red primarily because the hemoglobin includes a central iron,
> and chlorophyll has a central magnesium (I think that gives it the color,
> but I'm not a chemist). One could picture a planet that built its
> energy-collecting storage around a different element than magnesium and
> thus having a different base color, but again, I am NOT a chemist and I
> don't know how well the game works with other metals.
> ------ imagining a system where the plants picked arsenic to put at the
> core of their not-chlorophyll: definitely they'd be poisonous to earth
> critters. On the other hand, I don't think arsenic is ever likely to be as
> common as magnesium, so evolutionary attempts to use it would fail against
> other critters using magnesium. ------
> --

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