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Recurrence of a lunar phase
The full moon falls of the 16th this month (Nov '05). In what year will
it fall on this day of this month next? In other words, how often does a particular phase of the moon fall on a particular day of a given month? |
#2
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Recurrence of a lunar phase
Michael wrote: The full moon falls of the 16th this month (Nov '05). In what year will it fall on this day of this month next? In other words, how often does a particular phase of the moon fall on a particular day of a given month? It would fall on the same day of each month if we used a lunar calendar. However the word month was invented at the same time as the rest of astrometry so the use of the term was originally given to the divisions of the zodiac. In the early Roman era this was changed from a metric division to an irregulat restoration of the 12 months. However if they were regular 12 monthly intervals of 365.25* days, they would occur with divisions of 29.5* days imposed on a roll over of 30.5* days. But you have the odd month of February to contend with and the September, April, June and November -as the saying goes, 30 days. It takes something like 27.3* days for the moon to rotate around the earth. If we were not in orbit around the sun that would be the length of the month. Their dual relationship with the position around the sun the time of the run of phases is extended to about 29/30 days. However: The days are shorter when we are nearest the sun as the earth and moon are running through the orbit fastest then reducing the time to run through the lunar phases. At apogee (the point in the orbit of the moon or of an artificial satellite most distant from the center of the earth) the earth and moon are moving a little slower past the sun, so extending the time taken to produce a full house. In short, without the algorithm required to work it out, you had best look at the remarkable effort produced by the much revered Dr Espenak: http://sunearth.gsfc.nasa.gov/eclips.../phasecat.html It misses it it by a day in 2013 as it does again in 2024. For more chances try: http://sunearth.gsfc.nasa.gov/eclips.../phasecat.html (Nice one, Freddie) |
#3
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Recurrence of a lunar phase
Michael (or somebody else of the same name) wrote thusly in message
.com: The full moon falls of the 16th this month (Nov '05). In what year will it fall on this day of this month next? In other words, how often does a particular phase of the moon fall on a particular day of a given month? It takes 19 years (a complete Golden Number sequence) for this to happen again since only after this many years is the number of lunar months close to an integer (236). So the full moon should fall on 16 November in 2024, then in 2043, etc. (This synchronism is not quite exact, drifting out by one day in about 300 years. It was better when we used the Julian calendar.) -- Pelagiarism: passing off somebody else's heresy as your own Interchange the alphabetic letter groups to reply |
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