Full Moon Cycle and The Year
Formulated in another way: the full moon cycle is the period that it takes the Sun to return to the perigee of the Moon's orbit (as seen from the Earth). So it is a kind of "perigee year", similar to the eclipse year which is the time for the Sun to return to the ascending node of the Moon's orbit on the ecliptic.
Why does a full moon cycle last almost 14 lunations rather than just the 12.37 lunations of a year? This would be the case, if the moon's orbit kept a constant orientation with respect to the stars, but the tidal effect of the Sun causes the orbit to precess over a cycle just under 9 years. In that time, the number of full moon cycles passed becomes one less than the number of sidereal years passed.
Hence the full moon cycle can be defined such that the lunar precession cycle is the beat period of the full moon cycle and sidereal year. See lunar precession.
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Famous quotes containing the words full, moon, cycle and/or year:
“There, full in notes, to ravish all
My Earth, I wonder what to call
My dullness; when
I heare thee, prettie Creature, bring
Thy better odes of Praise, and Sing,
To puzzle men:
Poore pious Elfe!
I am instructed by thy harmonie,
To sing the Time’s uncertaintie,
Safe in my Selfe.”
—George Daniel (1616–1657)
“Though it seems improbable on the face of it
You must master the huge retards and have faith in the slow
Blossoming of haystacks, stairways, walls of convolvulus,
Until the moon can do no more. Exhausted,
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Though the experiment is a mess.”
—John Ashbery (b. 1927)
“The cycle of the machine is now coming to an end. Man has learned much in the hard discipline and the shrewd, unflinching grasp of practical possibilities that the machine has provided in the last three centuries: but we can no more continue to live in the world of the machine than we could live successfully on the barren surface of the moon.”
—Lewis Mumford (1895–1990)
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—Mark Twain [Samuel Langhorne Clemens] (1835–1910)