Moonphase on an annual calander.

[Custom02]

The instructions to my 5396 state:

''Annual Calendar models feature an extremely accurate moon-phase
display that deviates from the true lunar cycle by only
one day every 122 years...''

If a full moon comes around every 29.5 days how is it possible to set it correctly if one can only alter by 1 full day? It's a full moon tonight and the moonphase on my watch is in the position in should have been yesterday- despite last setting it on the 17th (the last full moon)!!!

[GoingPlaces]

Good question. I would like to see what people's thoughts are on this.

[gpwhite]

Interesting question!!
True, it does appear that the moon dial indicates only 15 discrete positions, although I have never observed/ photographed the phenomena precisely (the dial is a duplicate pattern, so 2 x 15 = 30 days, as you noted).
More importantly, I would think, the engine for the moon phase indication, which is the going train, is itself promised to be accurate only 5s x 365.25 x 122 years = approximately 2.6 days of supposedly maximum deviation!! Of course, one would need to lubricate the movement several times to achieve that duration anyway.

Why not write Patek Geneva and ask for an explanation of their marketing pfooey? Actually, Lange does the same thing about an 1815 Moon Phase watch I have.

[Russell996]

Originally Posted by Custom02

The instructions to my 5396 state:

''Annual Calendar models feature an extremely accurate moon-phase
display that deviates from the true lunar cycle by only
one day every 122 years...''

If a full moon comes around every 29.5 days how is it possible to set it correctly if one can only alter by 1 full day? It's a full moon tonight and the moonphase on my watch is in the position in should have been yesterday- despite last setting it on the 17th (the last full moon)!!!

Moon phases are always an interesting topic. The correct period (synodic month) is 29 days, 12 hours, 44 minutes, 2.9 seconds. The actual time to rotate the earth (sidereal month) is 27 days, 7 hours, 43 minutes and 11.5 seconds but due to the earth and moon moving around the sun the angle of illumination has changed and hence the apparent phase is longer.
1 day in 122 years is actually a very low level of accuracy and equates to about 12 minutes a year and as you have spotted the setting is not very accurate but probably adequate given it's overall accuracy (I assume for best accuracy you can set the piece to full moon date, set the time to GMT full moon time and set the full moon on the display - then adjust the time back/forward multiple days as required to get the watch date and time set correctly?).
Pieces like the UN Tellurium run with an accuracy of 1 day per 144,000 years (0.6 seconds per year) and are always set to a full or a new moon as the starter point before setting the time - it also shows the actual position of the moon around the earth and the earth/moon in relation to the sun. (plus many other things including world time, perpetual calendar, solar and lunar eclipses, sunrise and sunset times for all points on the earth etc etc)

Images from UN Trilogy of Time Book.

[yessir69]

Good lord that was a detailed and good answer.


Sent from my iPhone using Tapatalk

[Aquaman]

Originally Posted by Russell996

Moon phases are always an interesting topic. The correct period (synodic month) is 29 days, 12 hours, 44 minutes, 2.9 seconds. The actual time to rotate the earth (sidereal month) is 27 days, 7 hours, 43 minutes and 11.5 seconds but due to the earth and moon moving around the sun the angle of illumination has changed and hence the apparent phase is longer.
1 day in 122 years is actually a very low level of accuracy and equates to about 12 minutes a year and as you have spotted the setting is not very accurate but probably adequate given it's overall accuracy (I assume for best accuracy you can set the piece to full moon date, set the time to GMT full moon time and set the full moon on the display - then adjust the time back/forward multiple days as required to get the watch date and time set correctly?).
Pieces like the UN Tellurium run with an accuracy of 1 day per 144,000 years (0.6 seconds per year) and are always set to a full or a new moon as the starter point before setting the time - it also shows the actual position of the moon around the earth and the earth/moon in relation to the sun. (plus many other things including world time, perpetual calendar, solar and lunar eclipses, sunrise and sunset times for all points on the earth etc etc)

Images from UN Trilogy of Time Book.

Head fecked

[Ballzzz]

This is the type of stuff I like!

[Custom02]

Yes thank you for those two concise answers. I kind of thought as this wasn’t a nautilus-aquanaut waiting list/price related thread it might have got totally overlooked!!

Thanks again

[Commonproject]

Originally Posted by Russell996

Moon phases are always an interesting topic. The correct period (synodic month) is 29 days, 12 hours, 44 minutes, 2.9 seconds. The actual time to rotate the earth (sidereal month) is 27 days, 7 hours, 43 minutes and 11.5 seconds but due to the earth and moon moving around the sun the angle of illumination has changed and hence the apparent phase is longer.
1 day in 122 years is actually a very low level of accuracy and equates to about 12 minutes a year and as you have spotted the setting is not very accurate but probably adequate given it's overall accuracy (I assume for best accuracy you can set the piece to full moon date, set the time to GMT full moon time and set the full moon on the display - then adjust the time back/forward multiple days as required to get the watch date and time set correctly?).
Pieces like the UN Tellurium run with an accuracy of 1 day per 144,000 years (0.6 seconds per year) and are always set to a full or a new moon as the starter point before setting the time - it also shows the actual position of the moon around the earth and the earth/moon in relation to the sun. (plus many other things including world time, perpetual calendar, solar and lunar eclipses, sunrise and sunset times for all points on the earth etc etc)

Images from UN Trilogy of Time Book.

So it's not accurate? Literally unwearable

[SL BRABUS]

Moon phase is an icon on a Patek dress watch......

[Russell996]

Originally Posted by Commonproject

So it's not accurate? Literally unwearable

Well at 1 min a month the moon-phase might be less accurate than the time if your piece can beat 2 seconds a day.

[Sam Philip]

Came across the following article describing the 8 most accurate moon phase wrist watches.

https://quillandpad.com/2018/01/13/8...tches-archive/

[tchaic]

Originally Posted by Custom02

Yes thank you for those two concise answers. I kind of thought as this wasn’t a nautilus-aquanaut waiting list/price related thread it might have got totally overlooked!!

Thanks again

Ha! Great to see something different talked about!

[Aquaman]

Originally Posted by tchaic

Ha! Great to see something different talked about!

agreed so may rogues around here nice to be different