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The complete guide to the moon phase watch

In this guide, let’s look at the history of the moon phase complication, the technical definition of moon phases, how these watches work and how to set one.

Header phase de lune

What is a moon phase watch?

A moon phase watch is a type of complication watch, such as the tourbillon watch which we mentioned in another article. This complication watch, with its distinctive style and mysterious aura, displays the different phases of the moon through an opening in its dial. Moon phase watches have been around for centuries, and are still popular today because they offer a unique way to track the progress of the moon.

Definition of the different phases of the moon

There are eight different phases of the moon: new moon, first crescent, first quarter, waxing gibbous moon, full moon, waning gibbous moon, last quarter, last crescent.

The moon phase watches highlight 4 of the 8 phases of the moon. These are the new moon, first quarter, full moon and last quarter.

The different phases of the moon can be used to track the weather, predict the tides and even plant crops. Whether you are an experienced gardener or a vegetable gardening novice, a moon phase watch can be a useful tool in your gardening arsenal.

History of the moon phase complication

The Greek origins of the moon phase mechanism…

The earliest recorded historical example of a machine tracking the phases of the moon comes from the machine of Antikythera, an ancient Greek device that is said to have been created between 150 and 100 BC. Although the Antikythera mechanism was mainly used for astronomical purposes, it laid the foundation for future moon phase complications.

The Antikythera mechanism is composed of dozens of interlocking cogwheels arranged on several planes. It is a complex and fascinating piece of engineering, giving us a glimpse of the sophisticated technology of the ancient Greeks. The Antikythera machine reminds us of the progress made by our ancestors and testifies to the ingenuity of the human mind, which was already trying to master time.

… To the first contemporary moon phase complications

It was not until 1925 that Patek Philippe, famous Swiss manufacturer released the first moon phase watch. This watch, known as the Perpetual Calendar 97975, is the first classic watch to feature this type of mechanism. In fact, Patek Philippe had already developed this movement and in 1898 issued a moon phase pendant for women.

Since then, moon phase complications have become increasingly popular among collectors and watch enthusiasts. Today, there are many types of moon phase dials, each with its own unique aesthetic.

Perpetual Calendar Patek Philipp

The different types of moon phase dials

Moon phase watch with crescent dial

The crescent dial moon phase watch is the most popular type of moon phase watch. It uses a crescent-shaped aperture to draw the silhouette of the Earth.

Moon phase watch with radial dial

Radial moon phase watches are a type of watch that uses a hand to indicate the current phase of the moon. Radial moon phase watches are a type of watch that uses a hand to indicate the current phase of the moon.

Montre à phase de lune à cadran en croissant

Montre à phase de lune à cadran radial

What are the differences between a moon phase watch and a day/night watch?

Moon phase watches are a type of watch whose complication allows them to display the different phases of the moon.

The day-and-night watches, on the other hand, are equipped with a dial displaying the sun during the day and the moon at night. These are watches that indicate A.M. and P.M. in a slightly different way to the more traditional models, and are valued primarily for their design and not for their functionality… unless you live in one of the two polar circles.

Moon phase watches: more complex and high-end than day/night watches

Moon phase watches are truly unique timepieces. This complication is much more complex than a day/night watch and, as a result, moon phase watches are often more expensive.

However, for many collectors, this additional complexity is well worth the price. Moon phase watches are often made of noble materials such as gold and aventurine, and their complex dials are true works of art.

In addition, moon phase watches have a special symbolism for many people. For some, they represent the changing seasons or the cyclical nature of life. For others, they recall the romantic mystery of the night sky.

For others, they recall the romantic mystery of the night sky.

How moon phase watches work?

The phase watch has a disc decorated with two moons. This disc completes one complete cycle every 29.5 days, mimicking the orbit of the moon around the Earth.

In the case of the classic models, this disc is driven by a 59-tooth gear that advances by one notch every 24 hours. The moon phase watch is a good choice for those who want to follow the phases of the moon and have a unique and elegant timepiece.

How accurate are moon phase watches?

The accuracy of a moon phase depends on the gear on which it is based, and the number of teeth in that gear. Traditionally, moon phase watches are fitted with 59 teeth, and require readjustment every two and a half years. However, you can also find very luxurious versions with more teeth, which offer greater precision.

How to set a moon phase watch?

As you can imagine, there are different types of moon phase complications, with different levels of complexity. Here are some tips on how to set your moon phase watch (unless otherwise stated in the instructions supplied with your watch).

  • Before setting the moon phase complication, pull out the crown and turn the hands to the 6:30 position. This is done as a precaution – in case their position might damage the movement when you set the moon phase.
  • It is then important to know whether the Moon is waxing or waning when you make the adjustment. You can use the Internet to find out what phase the Moon is in at any given time.
  • Once you know the phase of the Moon, rotate the disc so that the full Moon (or new Moon) appears in the middle of the window. Then count the days since the last full or new moon.
  • Then turn the crown to bring the Moon to its current phase (as a general rule, you advance it one step for each day since the last Full Moon or New Moon). Push the crown back into its normal position… That’s it, you have just set your moon phase watch.

A true miniature work of art with a strong symbolism, the moon phase watch still fascinates. Are you interested in the complex mechanics of this type of watch? Why not visit one of our workshops where you can enter the unique world of Swiss watchmaking alongside master watchmakers.

Build your own Swiss watch now.