Re: Stereo of the Moon

[P3D Dr. George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx>]

>The earth is about 8000 miles in diameter and the moon is about
>250,000 miles away. If all the conditions were right; moonrise at
>sunset and moonset at sunrise, etc, and you took a picture at both 
>times. Then the ratio would be 8000:250,000 or about 1:30 which is
>what I think we shoot for. Any comments?

Yes.  Assuming that your numbers are correct, 1/30 is the ratio of the
diameter of the earth to the distance of the moon.  So, if someone was
standing at one end of the earth and took picture of the moon at moonrise
and someone else was standing at the other end of the earth and took
another picture at moonset _at the same time_, then we would have a good
stereo of the moon.

But, if the same person is going to take two pictures at different times
from the same location in a 12 hour period, we are talking about a
different situation.  The moon has the bad habbit of showing us the same
face at all the times, which makes stereo of the moon _from the same
location_ impossible.  

Well, almost.  It is this "almost" (small variations in the rotation of 
the moon) that make the stereo of the moon from the same location not
impossible, but just difficult.

George Themelis, at photo-3d, stereo lunch break...

...once wanted to be an amateur astronomer but 3d killed that too! 


------------------------------