More Mars color controversies.

I was watching those news conferences and that image did *not* have a blue
sky like the one shown on this web page! It may be because of the video
projector used and the cameras which took that image in the auditorium, or
that image may have been altered by those who put it up on the web site. The

Martian sky is not that blue!
--
David W. Knisely


Assuming ONLY "normal" gases in the atmosphere, the sun being high in the
martian sky, virtually NO water vapor, and (the big IF here) no supsended dust
particles....mars should be as blue or "bluer" than any blue sky seen here on
earth....of course deciding when blue fades to black is a whole other
issue.....

take care

Blll

Blll posted:

Assuming ONLY "normal" gases in the atmosphere, the sun being high in the
martian sky, virtually NO water vapor, and (the big IF here) no supsended dust
particles....mars should be as blue or "bluer" than any blue sky seen here on
earth....of course deciding when blue fades to black is a whole other
issue.....

The dominant coloring mechanism of the Martian atmosphere is the dust
component. The only time blues are often seen is either with high-altitude
clouds or near sunset. This has been demonstrated by properly calibrated
images taken by Viking and Pathfinder. Other than this, the sky on Mars isn't
blue.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 11th Annual NEBRASKA STAR PARTY *
* July 18-23, 2004, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************

Note I said NO or little dust...

And there are times when the dust settles out....though most of the time there
is plenty of it suspended....

I guess I was trying to point out that mars sky COULD be a very nice
blue....but most of the time it sure isnt...

take care

Blll

David Knisely wrote in message .. .
Blll posted:

Assuming ONLY "normal" gases in the atmosphere, the sun being high in the
martian sky, virtually NO water vapor, and (the big IF here) no supsended dust
particles....mars should be as blue or "bluer" than any blue sky seen here on
earth....of course deciding when blue fades to black is a whole other
issue.....

The dominant coloring mechanism of the Martian atmosphere is the dust
component. The only time blues are often seen is either with high-altitude
clouds or near sunset. This has been demonstrated by properly calibrated
images taken by Viking and Pathfinder. Other than this, the sky on Mars isn't
blue.
The component of Mars skylight resulting from the scattering by
atmospheric gasses is blue, only quite faint because of the thinness
of the Martian atmosphere. Forward scattering by dust causes the pink
color and completely dominates the blue. It is interesting that at
sunset the sky turns blue just before the sun sets.
Clif Ashcraft

In message , Clif
writes
David Knisely wrote in message
. ..
Blll posted:

Assuming ONLY "normal" gases in the atmosphere, the sun being high in the
martian sky, virtually NO water vapor, and (the big IF here) no
supsended dust
particles....mars should be as blue or "bluer" than any blue sky
seen here on
earth....of course deciding when blue fades to black is a whole other
issue.....

The dominant coloring mechanism of the Martian atmosphere is the dust
component. The only time blues are often seen is either with high-altitude
clouds or near sunset. This has been demonstrated by properly calibrated
images taken by Viking and Pathfinder. Other than this, the sky on
Mars isn't
blue.
The component of Mars skylight resulting from the scattering by
atmospheric gasses is blue, only quite faint because of the thinness
of the Martian atmosphere. Forward scattering by dust causes the pink
color and completely dominates the blue. It is interesting that at
sunset the sky turns blue just before the sun sets.
Clif Ashcraft

When I was a boy (don't ask :-) amateur astronomers and some
professionals talked about a "violet layer" in the atmosphere, and "blue
clearing" when the layer disappeared and the surface was visible in blue
and violet light. Are those ideas still current, and could it be due to
dust in the atmosphere settling out?
--
Rabbit arithmetic - 1 plus 1 equals 10
Remove spam and invalid from address to reply.

Jonathan Silverlight wrote:

When I was a boy (don't ask :-) amateur astronomers and some professionals talked about a "violet layer" in the atmosphere, and "blue clearing" when the layer disappeared and the surface was visible in blue and violet light. Are those ideas still current, and could it be due to dust in the atmosphere settling out?

The "blue clearing" is something of a mere contrast effect rather than any
sort of "clearing". The classical albedo markings do not show up well at all
in the blue and violet parts of the spectrum. As such, if the light areas
surrounding them become brighter or lighter due to some dust activity, the
darker areas will appear with a bit more contrast with respect to the lighter
regions. The effect is most dramatic in the blue because these images
normally show no markings and any slight increase in contrast will cause the
markings to emerge. Similarly, the so-called "wave of darkening" is also a
contrast effect in which the lighter regions are becoming lighter in color and
brightness due to dust activity, which makes the dark areas seem to stand out
more strongly. Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 11th Annual NEBRASKA STAR PARTY *
* July 18-23, 2004, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************

Mars color comes from iron oxide given off by its volcanoes when they
were active.It now lies on the ground,and is picked up by Mars dust
storms,and dust devils. This gives the air its reddish hue. The Earth
is a blue planet because our atmosphere,scatters the sun's high energy
photons. At sun rise,and sun sets we see red because the dust in our air
lets low energy photons through.and blocks out high energy photons. I
have sun glasses on that are red. The glass lens only lets red photons
through. I can't see Mars having a blue sky,but I could be wrong.
Maybe the spirit will look straight up. Bert

Well I found pictures I had stored away on the true color of Mars
surface. These pictures were radioed back and are close ups in true
color by the pathfinder. The surface is a true red. The rocks are
black,and have red dust on their tops. The horizon goes to a white
sky. The picture is in great focus,and shows part of the lander,and it
has some red markings to compare the red with. The next picture I have
is so very great. It shows a Martian sun set. The sun is setting in back
of hills(there very black) There is a very faint hint of blue near the
sun,and the rest going up in the sky is light hazy red. Well Mars
reflects back red light. It is literally a red planet. Red makes
mammals mad,and that is why Mars is used as a simile.of war. Bert