Need a Math Function for the Moon's earth high noon location in Time.

Douglas Eagleson wrote:

"Greg Neill" wrote in message ...

"Douglas Eagleson" wrote in message
.com...

I need to go to the geographic high noon for the moon, right here on
earth. And I asked the Naval Observatory to help with a function to
allow this to be done. That did not work, because they evidently
never have needed to find this location.

I need to go there for an astronomy expedition! I want to do clock
and pendulum and any other neat thing to test.

Can you provide a non-vague definition for what you
mean as "geographic high noon for the moon"?

Keep in mind that the Earth turns, so any given alignment
with the Moon will be fleeting.



Sorry for the vague definition. Take the line drawn between the
center of the two masses.

Like an exact 90 degree angle with respect to a sextant user for all
horizon directions. I guess that means that all compass directions
are valid for angle measurement.

Maybe a satillite function for low earth orbit examples could be
synchronized?
Except I need lattitude and longitude to find the spot on the earth.

So are you asking for predictions of geographic locations and times
when the moon will pass directly overhead? Put another way, are you
looking for a plot on a map of the earth of the "sub-lunar" point as
a function of time? How accurate do you need to be (the moon can
only be _exactly_ overhead for an instant)?

To a first order, use any of the many ways of finding the moon's
declination (about +22.25 degrees tonight) ... places at that
latitude will see the moon pass directly overhead at its meridian
transit time (about midnight for full moon, 6AM for 3rd quarter,
noon for new moon, 6PM for 1st quarter).

For example, tonight the moon will pass less than 1 degree from
directly overhead in Havana Cuba about 15 minutes before midnight.
--
John Oliver
Associate Professor
Associate Chair/Undergraduate Coordinator
Department of Astronomy
University of Florida
Project AST@RHO http://astrho.astro.ufl.edu
see the night sky at http://concam.net/rh/