Re: Stereo of the Moon

[P3D Peter H. Coffin <hellsop@xxxxxxxxxx>]

Dr. T writes:

> 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.

I'm not sure that this is entirely correct.  The moon shows the same face
to the Earth's center of gravity, but we stand on the surface. So, during
one Earth rotation, some guy pointing his camera at the moon (regardless of
whether the Earth is in the way at the time), ends up travelling in a
circle around the point at which the Moon is facing. Assuming that our
photographer spent a pile of money on a South American vacation and is up
in the Andes, he'll be able to take pictures at moonrise while standing
4000 miles on one side of the point at which the moon is facing, then at
moonset, 4000 miles on the other side.

Assume the period character is Dr T on a mountain top, the parens are the
Earth, and the o is the Moon.  Angle of the camera shot is shown by the
slashes.

Moonrise         Moonset
  .(*)             (*).
   \                 /
    o               o

During all of this, Dr. T does get to ride effectively nearly 8000 miles,
from one side of the planet to the other. The moon's face, of course, stays
exactly pointed at the * in the center of the ( ).

Going anywhere after Greece, Doc?



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