How To Read A Moon Phase Watch

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Do you want to learn how to read a moon phase watch?

If you have purchased a new moon phase watch and want to know how to read it then you are reading the right article. In this article, I will not only tell you how to read it but I will also tell you how do moon phase watches work, how to set a moonphase watch and why are they so expensive.

So keep reading!

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What Are Moon Phase Watches?

Before we learn to read one, let us first have a look at what actually are moonphase watches. If you already know this then you can skip this part and go to the next section.

Moon phase watches, in layman’s terms, are watches that show you the different phases of the moon. So if you own a moon phase watch then you will not have to look at the sky to see the phases of the moon. You can simply look at your watch and know if it’s a new moon, first quarter, full moon, or the last quarter.

Different Types Of Moon Phase Watches

There are basically two types of moon phase watches:

  • Bosom moon phase watches
  • Radial moon phase watches

Bosom moon phase watches are the watches that make use of a cutout window to show the different phases of the moon.

On the other hand, radial moon phase watches make use of an additional watch hand to show different moon phases.

Nowadays, most companies make bosom moon phase watches, and hence they are more common than radial moon phase watches. Therefore in this article, we are going to learn how to read bosom moon phase watches.

How To Read A Moonphase Watch?

How To Read Moon Phase Watch

Reading a moonphase watch is actually very easy once you get a hang of it.

To read a moon phase watch, you should first know about the lunar cycle. There are 4 main parts of a lunar cycle i.e. first quarter, full moon, last quarter, and new moon. One thing to note here is that the “quarter” in the first quarter and last quarter represents the time in days and not the shape of the moon.

If the lunar cycle has completed 1/4th of the cycle then it is known as the first quarter. Similarly, when the lunar cycle has completed 3/4th of the cycle then it is known as the last quarter.

You can know more about moon phases by reading the lunar phase article on Wikipedia.

In the bosom moon phase watches, the cycle generally starts from the left and then ends to the right of the cutout window. So if the moon is on the left side of the window then it means the cycle is moving from a new moon to the first quarter. As days will pass, you will see the cycle move from the first quarter to the full moon. Once the moon is in the middle of the cutout window then it means that it is a full moon. As the days pass by, you will see the moon move from the full moon to the last quarter and then to the new moon. This keeps going on and on and represents the whole lunar cycle.

Just remember that if the moon is on the left side of the cutout window then the lunar cycle is moving from a new moon to a full moon. And as the moon starts moving to the right side from the full moon position then the cycle is moving from the full moon to the new moon.

How Do Moon Phase Watches Work?

How Do Moon Phase Watches Work

So this is how you read a moon phase watch, if you are now curious about the working of these watches then let us have a look at it.

In simple terms, to show the moonphase, under the cutout window lies a rotating disc that has two moons. And when this disc rotates you are able to see the different phases of the moon.

Let us now look at the rotation of this disc. In most watches, the rotation of this disc is made possible through 59 teeth. Why 59 teeth you ask?

A lunar cycle gets completed in 29.530587981 or 29.5 days. Since there are two moons on the disc, out of which one appears on the screen for 29.5 days, and the other moon appears for the next 29.5 days, so 29.5×2 = 59 days. Therefore the rotating disc completes one full rotation in 59 days and has 59 teeth to do it.

Are Moon Phase Watches Accurate?

Moon phase watches are not the most accurate as the actual lunar cycle gets completed in 29.530587981. However, the watches take into account only 29.5 days and lose out on 0.030587981 days. Therefore the moon phase of these watches will lose a whole day after every 2 years and 7.5 months.

To overcome this error, high-end luxury watches have 135 teeth to rotate the same moon disc. These watches are also known as Astronomical Moon Phase watches. The lunar cycle of these watches is the most accurate and they only lose 1 day in 122 years.

How To Set A Moon Phase Watch?

How To Set A Moon Phase Watch

Step 1: Press the button to set the moon phase until you see the full moon on the cutout window.

Step 2: Reverse the watch calendar by 1 day.

Step 3: Find out how many days it has been since the last full moon. You can take the help of calendar-365.

Step 4: Press the button ‘n’ number of times to set the moon phase. ‘n’ represents the number of days since it was the full moon minus 1. For eg., if the full moon was 10 days back then ‘n’ will be 10-1 = 9.

Step 5: Now set the current time, remember to rotate the clock one whole day so that the date in the calendar changes.

Step 6: Your watch is now showing the accurate time, date, and moonphase as well.

Why Are Moon Phase Watches So Expensive?

Why Are Moon Phase Watches So Expensive

As discussed earlier, implementing a moon phase complication in a watch is a very difficult task. It requires the addition of extra parts to the watch mechanism. And the addition of extra watch parts increases the overall cost of making the watch. In case the watch happens to be an astronomical watch, then the cost even goes higher because of the more advanced watch parts.

Therefore moon phase watches are more expensive compared to their counterparts.


What Is Moon Phase Indicator?

The Moon phase indicator as the name suggests is an indicator to show different phases of the moon.

What Is The Moon On The Watch?

The moon on the watch either represents the nighttime or represents the moon phase, depending from watch to watch.

Are Moon Phase Watches More Expensive Than Normal Watches?

Yes, moon phase watches generally cost more than a normal watch.

Tom Nielson

Tom's love for watches started when his grandfather gifted him his Rolex watch when he turned 18! Being a teenager it was a big deal for him. Later when he got his first job he bought Fossil Palm Pilot back in 2003 which was a smartwatch. Since then smartwatches have come a long way and so is Tom's love for them. His experience with watches inspired him to start Wearholic and share his knowledge of wearables including watches, smartwatches, smart glasses, & smart clothing.

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