A watch with moon phase is very popular among watch enthusiasts. Because a display in the dial that shows the current position of the moon not only looks very beautiful, it also contains stunningly ingenious technology that is hundreds of years old. But what exactly is a moon phase watch? And why would you choose a moon phase watch? In this blog we explain how this special watch complication works.
What is a moon phase watch?
A moon phase watch has a window in the dial where you can see the different phases of the moon, exactly as it looks in the sky at that moment. These phases of the moon are called moon phases.
Why a moon phase watch?
In this age of satellites and smartphones, we can hardly imagine it anymore, but for centuries humans depended on the sun and moon phases to determine the time. Sowing and harvesting crops, religious holidays, and for sailors, determining the high and low tide levels. The ancient Greeks even had a kind of calculator with which they could calculate the position of the sun, moon and planets.
That is why (astronomical) clocks were developed from the fifteenth century onwards on which you could see the position of the moon without having to go outside.
You can of course choose a moon phase watch because you like it, but the moon phase still has a function today. For example for military operations, outdoor sports enthusiasts and water sports enthusiasts. Although these groups usually opt for a modern digital watch that can predict and display the moon phases and water levels very accurately.
What is the difference between a sun and moon watch and a moon phase watch?
In addition to moon phase watches, there are also watches with a sun and moon display in the dial. Such a sun and moon watch only indicates whether it is day or night with the image of a sun or a moon, not the position of the moon.
How does a moon phase watch work?
Mechanical moon phase watch
In an analog mechanical watch, the moon phase is incorporated into the dial. Usually with a beautiful image of the moon as it looks in the sky on a certain night. To achieve this, a gear with 59 teeth drives a metal pin that is connected to the mechanism of the hour hand, causing it to click forward a notch every 24 hours and the moon to shift in the display. This cycle in turn follows the 29.53 day lunar cycle.
Wait a minute, 29.5 days? A month is 30 or 31 days, right? That’s right. In practice you will not notice much of this difference, but a mechanical moon phase – if the watch has been running continuously for 3 years – will lag almost 1 day behind. These watches must therefore be manually corrected at regular intervals (to be exact: 2 years, 7 months and two weeks).
Some mechanical watches contain a gear with 135 notches, which only needs to be adjusted once every 122 years. These are very accurate – often handmade – timepieces that we encounter, especially in the luxury top segment.
Analog Quartz moon phase watches
Quartz moon phase watches work broadly the same as mechanical moon phase watches. If the Quartz moon phase watch also contains a perpetual calendar, it will automatically correct for the deviation between 29.5 and 30 or 31 days.
Digital moon phase watches
No matter how beautiful an analog moon phase watch looks, if you depend on the exact moon phases, it is better to choose a modern digital watch. The phase of the moon determines the tides. Especially important for water sports enthusiasts. For example, what time the sun rises and sets is important for soldiers and outdoor athletes.
With digital watches, the calendar is usually pre-programmed for 100 years. If you have set your time zone/location correctly – and the watch has a moon phase or tide display – it will automatically display correctly. Digital watches with GPS or smartphone synchronization are even more current.
Which watch you choose depends entirely on what you want to do with it. If you only go sailing occasionally, a simple high-water table may be sufficient. But if you are a semi-professional surfer, extensive tide information is required. The water resistance of a watch also plays a major role.
How do you set a moon phase watch?
Always read the instructions carefully before setting your moon phase watch. Every brand and type of timepiece has its own way of setting. With mechanical watches there are two ways to set the correct moon phase: via the crown or via a special push button.
You have to be careful with watches with a moon phase complication because the mechanism is complex and sensitive. Check whether the watch is set to the correct date and time, as the moon phase and the date are linked.
Before setting the moon phase, first pull out the crown. You do this to prevent the movement of the hands from damaging the timepiece when you set the moon phase.
1. Then turn the moon disk so that the full moon is in the center of the window.
2. Look up the current position of the moon, for example on the site http://www.antique-horology.org/PDAmoon/appmonth.htm
3. From the current moon phase, count the number of days since the last full moon.
4. Gently rotate the crown one tick (one notch) for each day to shift the moon to the correct current phase. For watches with a push mechanism, you press once per day.
5. Push the crown back into its normal position and you’re done.
Having trouble setting the moon phase yourself? Then visit one of our stores. We are happy to help you!
Moon phase watches at Techzle
Whether you go for the aesthetics of a classic moon phase watch or a hyper-modern version, know that there is always special and advanced technology behind it. Visit one of our stores or make a call with the expert and get advice about which moon phase watch suits you best.
*Source: https://nl.wikipedia.org/wiki/Mechanisme_van_Antikythera