# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: An exotic lunar distance puzzle
From: David Fleming
Date: 2011 May 5, 13:01 -0700

Marcel,

Thanks for catching the error in mixing km with mile in calculating dip.

cos ( GeoDip) = 1 / ( 1 + (hE/RE))

take RE = 3953 mi + 8 mi

he = 211 mi

GeoDip = 18.3 deg

According to Wikipedia article on atmospheric refraction, it is proportional to pressure. At 20 km pressure is 1/10 that at surface of earth. Earth surface 0d Altitude refraction is 34m. So we might expect a 3.4m refraction correction to the 18.3d geometric dip.

As I have said in the past, parallax for the moon is 1d. That is the moon appears 1 deegree low toward horizon. Can somebody check me on that?

If we identify the stars properly and the photo is undistorted then the coordinates of the moon can be determined and the time of the photo inferred.

Thanks,
Dave

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