Re: Martian sky color

["John S. Denker" <jsd@AV8N.COM>]

Sorry for the not-so-prompt response.  My note was delayed and
bounce, twice, by buggy software at nau.edu.
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Quoting Mark Sylvester <msylvest@XNET.IT>:

> Looking out of my window through the bare trees outside, I observe that the
> earth sky is grey!

That's an important point to keep in mind.  There is some
nifty physics that explains why the sky "is" blue ... and all
too often people let the theory run roughshod over the facts.
In fact there are many times and places where the sky is not
blue.

  http://www.av8n.com/physics/blue-sky.htm

> Does the Earth's blue sky have anything to do with the light-scattering
> properties of oxygen molecules?

There's nothing special about oxygen.  Of course the sky-light
has "something" to do with the scattering properties of oxygen
and nitrogen, notably the fact that they scatter.

> What do we expect the Martian sky to look
> like as a consequence of the atmospheric composition of Mars?

In the (hypothetical, unrealistic) absence of dust, I would
expect the atmosphere of Mars to be almost black, with a tinge
of blue.

Given the highly variable but generally large amount of dust,
I would expect it to be whitish.  Maybe somewhat red if the
dust is really strongly colored.  I would expect the *sunsets*
to be red, for the same reasons that Arizona sunsets are red, i.e.
all the blue has been subtracted.