Re: why are moonrise durations uneven?

On Mar 25, 7:55 am, br...@xxxxxxxxxxxx (Brian Tung) wrote:
aloha.mor...@xxxxxxxxx wrote:
I've just noticed that the durations between one day's moonrise time
and the next day's moonrise time are not equal. Instead of a one-day
rise-time difference of say, 49 minutes, it varies in a regular two-
week pattern between 34 minutes and 64 minutes. Why? The moon orbits
the earth at a steady rate so the daily rise time difference should
always be the same (approximately 24 hrs X 60 minutes/hr / 29 days (in
one orbit)).
Anyone know the answer?

Sure.  It's much like the Sun, except that where it takes the Sun a year
to go through an entire cycle, from long days (summer) to short days
(winter) back to long days again, it only takes the Moon a month.

For part of the cycle, the Moondays (the time when the Moon is above the
horizon) are getting longer and longer, and the time between successive
moonrises is shorter than average.  For the other part of the cycle, the
Moondays are getting shorter, and the time between successive mooonrises
is longer than average.  These even out, so on average, the time between
the moonrises is what you would calculate it to be, it does vary.

The reason that some Moondays are longer than others is the same as it
is for the Sun: The Moon takes a higher path at some points than it does
at others.  A simple rule of thumb: If the Moon is N days old, it takes
the same path as the Sun will 2N weeks from now.  Not quite right, but
close enough for government work.

--
Brian Tung <br...@xxxxxxxxxxxx>
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The same path as the Sun indeed !,every single description of any
motion in the celestial arena in this forum is based on a mixture of
geocentric and astrological yet even I concede that there is a point
where it appears that nobody really cares whether the Earth is moving
or not or how the apparent motions of the Sun translate into the
motions of the Earth.

To CalGirl - Kepler never proposed a 'law' of planetary motion and the
correlation he proposed between orbital periods and distance from the
Sun requires planetary comparisons include retrogrades -

"The proportion existing between the periodic times of any two planets
is exactly the sesquiplicate proportion of the mean distances of the
orbits, or as generally given,the squares of the periodic times are
proportional to the cubes of the mean distances." Kepler

Newton's vandalism of this simple correlation is so stupid that it can
only appeal to those who have an intense dislike of astronomy even
though it is now a dominant view -

"That the fixed stars being at rest, the periodic times of the five
primary planets, and (whether of the sun about the earth, or) of the
earth about the sun, are in the sesquiplicate proportion of their mean
distances from the sun." Newton

The actual reasoning of Kepler is so enjoyable and so easy to
understand that only the ugliest part of human nature would work to
destroy it and temporarily destroy it the mathematicians have.It is
almost 400 years since he realised the relationship using the Earth
orbital period as a baseline whereas Isaac and his followers use
celestial sphere geometry,and astrological 'sidereal time' framework
and the calendar system to create a conceptual monster.

What person here cannot enjoy the basic relationship which requires no
math but a simple acknowledgment that orbital motions of all planets
around the Sun,including apparent retrogrades are based on what we see
from a moving Earth ? -

"...if you want the exact time, was conceived mentally on the 8th of
March in this year One Thousand Six Hundred and Eighteen but
unfelicitously submitted to calculation and rejected as false,
finally, summoned back on the 15th of May, with a fresh assault
undertaken, outfought the darkness of my mind by the great proof
afforded by my labor of seventeen years on Brahe's observations and
meditation upon it uniting in one concord, in such fashion that I
first believed I was dreaming and was presupposing the object of my
search among the principles. But it is absolutely certain and exact
that the ratio which exists between the periodic times of any two
planets is precisely the ratio of the 3/2th power of the mean
distances, i.e., of the spheres themselves; provided, however, that
the arithmetic mean between both diameters of the elliptic orbit be
slightly less than the longer diameter. And so if any one take the
period, say, of the Earth, which is one year, and the period of
Saturn, which is thirty years, and extract the cube roots of this
ratio and then square the ensuing ratio by squaring the cube roots, he
will have as his numerical products the most just ratio of the
distances of the Earth and Saturn from the sun. 1 For the cube root of
1 is 1, and the square of it is 1; and the cube root of 30 is greater
than 3, and therefore the square of it is greater than 9. And Saturn,
at its mean distance from the sun, is slightly higher than nine times
the mean distance of the Earth from the sun." Kepler

There is nothing remotely close to the outrageous scandal of astronomy
being dominated by astrological precepts for the last 300 years which
have temporarily obliterated the ability to work with structural
astronomy by negating the Earth's motions by using timekeeping
averages to dictate structural astronomy.It is many,many magnitudes
more harmful that any financial crisis insofar as the currency is the
Western merit system and the great work of so many astronomers
stretching back to remote antiquity.

With the power of modern imaging it is now so easy to enjoy the
correlation which Kepler wrote about yet where is the support ?.






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