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> From: "Bill Noyce" 

> I'll take a shot at answering some of Bill's questions...
>
> The "magic number" 0.2724 isn't an angle, it's simply the ratio
> moon_radius / earth_radius
> SD is the angular distance of the moon's radius as seen from the
> earth, and similarly HP=SD/0.2724 is the angular distance of the
> earth's radius as seen from the moon, which is another way of
> describing the parallax of the moon at the horizon.  When we're on the
> line from the center of the earth to the moon, parallax is zero (and
> Ho=90 degrees).  For intermediate cases, cos(Ho) represents how far
> from that centerline we are, and thus how much of the HP to include.

Thank you Bill.  I guess what mislead me was the N.A. presentation of the
0.2724 constant which is does present as an decimal degrees. I am still
pondering it.

Bill N.


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