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Q: Moon's Sky ( No Answer,   3 Comments )
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Subject: Moon's Sky
Category: Science > Astronomy
Asked by: nosecone1023-ga
List Price: $20.00
Posted: 27 Dec 2005 08:10 PST
Expires: 28 Dec 2005 16:23 PST
Question ID: 610112
If you were standing at the Apollo 11 landing site on July 20, 1969
and looked up at the sky, what would the sky look like? Would it be
black and filled with bright stars? How would the Earth appear?

Request for Question Clarification by pafalafa-ga on 27 Dec 2005 09:02 PST
nosecone1023-ga,

Interesting question.

One would expect a vast starry sky, but the photos from Apollo 11 are
relatively star free.  You can see a great gallery collection herre:


http://www.apolloarchive.com/apollo_gallery.html


with an option, for any given photo, of viewing a hi-resolution
picture.  There's a whole series of earthrise photos included here.


There are definitely stars in some of the photos, although not in any
of the photos that show the earth (at least not as far as I can see). 
I imagine the overall radiance of the earth itself may render the
stars invisible.  The reflected radiance from the moon may also play a
role in making the stars harder to see than one would expect.

Let me know what you think.


pafalafa-ga
Answer  
There is no answer at this time.

Comments  
Subject: Re: Moon's Sky
From: brix24-ga on 27 Dec 2005 09:17 PST
 
I believe that you are referring to the issue raised in Science Challenge 24:

http://members.aol.com/painfulquestions/ScienceChallenge24.pdf

This site/pdf questions why the astronauts on the moon did not mention
stars in the moon's sky. The pdf has a picture and explanation on page
2 purporting to show that the astronauts would see the stars against a
black sky.

The problem with the picture is that it shows a person without the
gold face mask looking almost straight up. Most of the time, parts of
the lunar module or the moonscape were in view and the brightness of
the sun's reflection from these probably dwarfed any light from the
stars. I can't say whether the astronauts would have seen stars if
they looked straight up, but there would be a problem with the curved
gold facemask catching reflected light coming from the lunar module
and the moonscape. The effect of the curved mask is omitted from the
picture shown in the pdf cited above, which shows an astronaut looking
up in the lunar sky without a face mask.

The NASA quote, ?stars are not readily seen in the daylight lunar sky 
by either the human eye or a camera because of  the  brightness of the
sunlight surface? refers to a particular artist's conception of a moon
scene. If I go to the particular artist drawing that NASA is referring
to

http://www.hq.nasa.gov/alsj/a13/ap13-s70-31774HR.jpg

I see that the artist has drawn in stars, the lunar module, the
astronauts space suits, and some moonscape. These latter items will
reflect sunlight and the intensity of that light would most likely
swamp out any light from the stars - probably similar to the intensity
of earth's blue sky swamping out the light of the stars in the sky.
Subject: Re: Moon's Sky
From: qed100-ga on 27 Dec 2005 10:25 PST
 
As always with elements of Apollo Hoax Theory, one must relate the
question to what's already verifiable closer to home. In photos taken
from low Earth orbit, can stars be seen? They sure aren't visible in
the photographs. Can astronauts see stars from low orbit?

   As it turns out they can and they can't. It depnds on the overall
lighting circumstances. If ANY brightly light object is with one's
field of view, then the eye's iris will close down by some amount to
maintain a safe & comfortable luminosity on the retina. It's just like
how a photographer adjusts a camera to optimise the exposure of a
photograph. (Or nowadays, the camera may adjust itself automatically.)
In the case of starlight, it's just so faint that stars become
invisible when competing against objects as brightly lit as Earth, the
Sun, the Lunar surface, etc. And it's easy to demonstrate. Go outside
on a clear moonless night. Can you se the stars? Maybe. It depends on
what the circumstances are. I personally live way outside of town, and
the stars are quite bright. If I travel just three miles into town,
where there are street lamps and buildings and lots of cars, the only
stars I stand a chance of seeing are the very brightest ones, and even
then they appear faint. It's the same on the Moon.

   As has been mentioned, an astronaut on the Moon would have to stare
directly into the sky with *NO* bright objects anywhere. It's possible
to do this in some places. But the Apollo astronauts weren't there to
stargaze. They could do that back on Earth. They were there to conduct
geological expeditions, and had little time to do it. They had their
time scheduled carefully. There were few opportunities for any of the
Apollo crew to just stand in one spot and stare into black sky. The
only written account I've encountered of such an opporuntity was when
Jim Irwin happened to find about 1/4 hour in which he was free of
chores. So what did he do with that time? Well he certainly didn't
waste it trying to see the same stars that can be seen from Earth. He
spent it doing something he couldn't do back home, he played with the
low surface gravity.

   And keep in mind what I just said about the stars themselves. They
are the same on the Moon as on Earth. Even if the astronauts had made
some casual observations, there would be nothing remarkable to report,
with the notable exception of their "twinklelessness". (Mike Collins
does mention this in his book, "Carrying The Fire". On his Gemini EVA
he entered into Earth's night side. He had no choice but to ride it
out, during which he did pay attention to the number & clarity of the
stars. This was under conditions of pitch dark.)
Subject: Re: Moon's Sky
From: dremel99-ga on 27 Dec 2005 14:24 PST
 
http://www.badastronomy.com/bad/tv/foxapollo.html#stars

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