The Moon Phase Complication

[JohnBaker3]

Hey Guys:

Historically, the "phases of the moon" have been around just as long as the moon itself : ) Different cultures have different names, but the physics are not 100% straight forward as shown in the Wikipedia article below....

Anyway, over time, some watchmakers have added the "moon phase complication" to clocks, pocket watches, and now our beloved wrist watches.

This is accomplished using a rotating disk which is partially covered by 2 semi-circles inside a larger semi-circle opening. The dish rotates at the rate of of once every 29.5 days and shows the changing phases....

Setting the complication is pretty straight forward; a small button on the case side advances the phase until it matches what you see at your geographical location.

https://en.wikipedia.org/wiki/Moon_phase

[JohnBaker3]

Here's another picture that shows a better view of "the moon phase"

[cop414]

Excellent info John.

[JohnBaker3]

Thanks Tim....its getting harder and harder to find watch topics that someone else hasn't already done a thread about....

I think I'm getting down to the "nitty-gritty"....

[cop414]

Originally Posted by JohnBaker3

Thanks Tim....its getting harder and harder to find watch topics that someone else hasn't already done a thread about....

I think I'm getting down to the "nitty-gritty"....

Agree, here's a question though. So you have to "reset" the moon phase via the button each month? Very interesting.

[Abdullah71601]

Originally Posted by cop414

Agree, here's a question though. So you have to "reset" the moon phase via the button each month? Very interesting.

If it's on a 29.5 day cycle, why would it need to be reset each month? It seems like it's a regular cycle, not like the days of the month.

[cop414]

Originally Posted by Abdullah71601

If it's on a 29.5 day cycle, why would it need to be reset each month? It seems like it's a regular cycle, not like the days of the month.

Yea, that makes sense when you put it that way, so once you set it once you're done unless you're in a different location I assume. Interesting stuff!

[Abdullah71601]

Originally Posted by cop414

Yea, that makes sense when you put it that way, so once you set it once you're done unless you're in a different location I assume. Interesting stuff!

I'm going to guess that the moon phase is as accurate as the movement, so would need to be tweaked now and again due to the normal movement error. But otherwise, I wouldn't think you'd ever need to adjust it once it's set.

Probably need someone who has one or has worked on one to weigh in.

[JohnBaker3]

Originally Posted by cop414

Yea, that makes sense when you put it that way, so once you set it once you're done unless you're in a different location I assume. Interesting stuff!

+1

I haven't had mine long enough to see if the "gear math" is correct to 29.5 or 30 days....will be interesting to watch and report back!

[cop414]

John when you "advance" the phase via the button how far does the moon dial move?

[Abdullah71601]

Originally Posted by JohnBaker3

+1

I haven't had mine long enough to see if the "gear math" is correct to 29.5 or 30 days....will be interesting to watch and report back!

This statement is from the AP site for their perpetual calendar watch. Your results may vary, but it seems to indicate the principal of the moon phase complication...

"Moon phase astronomical indicator requiring correction every 125 years and 317 days"

[cop414]

Originally Posted by Abdullah71601

This statement is from the AP site for their perpetual calendar watch. Your results may vary, but it seems to indicate the principal of the moon phase complication...

"Moon phase astronomical indicator requiring correction every 125 years and 317 days"

Ummm... WOW!

[SearChart]

Some extra information for those who are interested.

[cop414]

Thanks Bas, simply amazing!

[SearChart]

Originally Posted by cop414

Thanks Bas, simply amazing!

Cheers Tim, I have a lot of info in this book, just ask if you want some info about other subjects, I can easily make some more pictures of pages in this book.

[witch watch]

Originally Posted by Abdullah71601

"Moon phase astronomical indicator requiring correction every 125 years and 317 days"

Pah! IWC quote 1 day adjustment in 577.5 years.

[cop414]

Originally Posted by SearChart

Cheers Tim, I have a lot of info in this book, just ask if you want some info about other subjects, I can easily make some more pictures of pages in this book.

Thanks, my bald headed brother!!

[SearChart]

Originally Posted by cop414

Thanks, my bald headed brother!!

[Abdullah71601]

Thanks Bas. Very cool.

[Abdullah71601]

Originally Posted by witch watch

Pah! IWC quote 1 day adjustment in 577.5 years.

Pah! I can look up at the sky and never need an adjustment!

They are all lovely complications.

[SearChart]

Originally Posted by Abdullah71601

Thanks Bas. Very cool.

You're welcome, Abdullah

[witch watch]

Originally Posted by Abdullah71601

Pah! I can look up at the sky and never need an adjustment!

They are all lovely complications.

True, true

[JohnBaker3]

Originally Posted by cop414

John when you "advance" the phase via the button how far does the moon dial move?

It appears to take 30 clinks to make a complete rotation of the moon phase dial...there are 2 moons on the disc spaced 180 degrees apart....so about 1/30 of a rotation...

[cop414]

Originally Posted by JohnBaker3

It appears to take 30 clinks to make a complete rotation of the moon phase dial...there are 2 moons on the disc spaced 180 degrees apart....so about 1/30 of a rotation...

Wow, thanks again for the info John.

[JohnBaker3]

Hey Guys:

Here is the best link yet on the Moon Phase Complication.....

http://gearpatrol.com/2015/04/14/com...the-moonphase/

[MADY111]

This a really a very good brand in watch.

[2ar2c1]

I assume complications like moon phase require a watch winder?

[JohnBaker3]

Originally Posted by 2ar2c1

I assume complications like moon phase require a watch winder?

If you don't want to constantly be re-setting the position of the complication, then yes...

Otherwise, just wear the watch daily and the oscillating weight keeps the watch wound and the complication(s) updated...



Photo via the internet....

[breitlings]

some people call it "their girlfriend/wife" complication, ha!

[JohnBaker3]

Originally Posted by breitlings

some people call it "their girlfriend/wife" complication, ha!

Took me a minute to catch that.....LOL....