[LMB] Chlorophyll

WILLIAM A WENRICH wawenri at msn.com
Sat Dec 25 17:05:44 GMT 2021

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

William A Wenrich

  *   A sinner dependent on God’s grace.

From: Lois-Bujold <lois-bujold-bounces at lists.herald.co.uk> on behalf of Karen Hunt <huntkc at gmail.com>
Sent: Saturday, December 25, 2021 9:50:17 AM
To: Discussion of the works of Lois McMaster Bujold. <lois-bujold at lists.herald.co.uk>
Subject: Re: [LMB] Chlorophyll

On Sat, Dec 25, 2021 at 11:33 AM WILLIAM A WENRICH <wawenri at msn.com> wrote:

> 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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