Re: [Phys-L] Trick photography?

[John Mallinckrodt <ajm@csupomona.edu>]

There is one other subtle effect related to the inclination of the Moon's orbit to the Earth's equatorial plane.  Because that inclination is only 5 degrees it doesn't produce very noticeable changes in the apparent rate of motion.  But imagine that the inclination were, say, 80 degrees.  In that case the apparent motion of the moon would depend strongly on the orbital phase.  Twice a month the moon would be found only 10 degrees away from a celestial pole and at those times its apparent motion would be very small.

John Mallinckrodt
Cal Poly Pomona

On Mar 3, 2014, at 8:23 AM, Bob Sciamanda wrote:

> I'm still learning (a good sign)! ==>
> I am just realizing that the apparent moon speed is NOT calculable as the 
> moon's linear orbital speed minus the linear spin speed of an earth surface 
> point.
>
> IE., Vap is NOT= {(6.28*250000)/(30*24) - (6.28*4000)/24} miles/hr.  This is 
> grossly wrong - even in direction!
>
> Instead, Vap = {6.28/(30*24)-6.28/24}*250000 miles/hr. => the relative 
> ANGULAR velocity times the moon's orbital radius.
>
> It is incorrect to treat the earth observer as viewing a  linear motion from 
> a linear moving frame. We must acknowledge that the earth observer is 
> viewing a rotational motion from a rotational frame.  Note that this turns 
> the moon's actual EASTWARD motion into the observed WESTWARD motion.  The 
> linear mistreatment fails to even do this.
>
> Again, thanks to John M for leading me to this realization.
>
>
> Bob Sciamanda
> Physics, Edinboro Univ of PA (Em)
> treborsci@verizon.net
> http://sciamanda.com 
>
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