moon phase or selene in oj blue
01
New moon02
Day after new moon03
Waxing crescent04
Waxing crescent05
Waxing crescent06
Waxing crescent07
Waxing crescent08
Waxing crescent09
Waxing Gibbous10
Waxing Gibbous11
Waxing Gibbous12
Waxing Gibbous13
Waxing Gibbous14
Waxing Gibbous15
Day before full moon16
Full moon17
Day after full moon18
Waning Gibbous19
Waning Gibbous20
Waning Gibbous21
Waning Gibbous22
Waning Gibbous23
Waning Gibbous24
Waning crescent25
Waning crescent26
Waning crescent27
Waning crescent28
Waning crescent29
Waning crescent30
Day before new moonReading the functions
The arrows next to the watch above allow you to show different phases of the moon.
Moon phase
The center represents earth and the large dot at 12 o’clock represents the sun. Full moon is when the moon is opposite the sun and earth at 6 o’clock. New moon is when the moon is hidden between the sun and earth at 12 o’clock. The new moon is represented by a dark circle at 6 o’clock.
Date
The 30+1 holes around the perimeter of the dial display the date. The 10 minute markers serve as reference points. For example: the marker indicating 30 minutes also shows the 15th day of the month (30÷2=15). These 5 day markers allow for the date to be read at a glance and after a short time, you can recognize the date intuitively. This video of Ludwig Oechslin explaining the date spiral for his perpetual calendar is also relevant for his moon phase watch.
Time
The exact minute and second can be read using the date holes, which are spaced at 2 minute intervals. Holes mark even minutes and gaps odd minutes. The holes and gaps are exactly the same width as the minute hand.
Mechanics
How is Oechslin’s moon phase function implemented?
An epicyclic gear train driven by a central finger bonded directly to the hour pipe turns the lunar disk beneath the dial counter-clockwise. The central finger engages with a wheel bearing 12 teeth, whose pinion with 14 teeth meshes with a wheel bearing 18 teeth, whose pinion with 14 teeth meshes with the fixed recessed ring gear with its 109 teeth machined into the underside of the dial (annotated diagram).
What is the benefit of a highly precise moon phase calculation?
The average time between two identical moon phases is 29.530589 days. Most moon phase watches approximate a lunation as 29.5 days, which leads their calculation to be off by 1 day after 2 years. The closer your moon phase calculation comes to the average lunation of 29.530589 days, the “flatter” the difference between your prediction and the actual moon phase. The ochs und junior moon phase calculates the lunation as 29.5306122449 days. As a result, it will predict the moon phase correctly for 3,478.27 years before it is off by 1 day. This means that you only have to set your moon phase one time, and you can trust that its prediction is precise.
Overview
Ludwig Oechslin’s moon phase watch displays the moon phase, date, and time. It features a unique moon phase function executed as a 5 part epicyclic gear system that will take 3,478.27 years before its calculation will be off by 1 day. The analogue, spiral date with dots is better readable than a digital display from the same distance, and brings the date in visual harmony with the clockwise display of hours and minutes.
Your moon phase watch
ochs und junior manufactures about 50 moon phase watches per year. Each watch is sold by us personally from our workrooms in La Chaux-de-Fonds.
Further information
Dimensions
42mm x 11mm (incl. crystal)
39mm x 11mm
Druck 1:1 (PDF)
Weight
42mm titanium: 70g (incl. leather strap and buckle)
39mm titanium: 62g
Water resistance
100m in titanium.
Case
2-part case in grade 5 titanium designed by Ludwig Oechslin.
Moon phase function
5-part epicyclic gear system designed by Ludwig Oechslin. The calculation is precise for 3,478.27 years before it is off by one day.
Date function
30+1 hole date spiral with 5 minute markers that serve as reference points designed by Ludwig Oechslin.
Base movement
ETA 2824-2 with 38 hours of power reserve. Manufacturer: ETA SA / Grenchen / Switzerland.
Crown
Screw-down crown in grade 5 titanium designed by Ludwig Oechslin (39mm and 42mm). Manufacturer: Pibor SA / Glovelier / Switzerland.
Buckle
Designed by Ludwig Oechslin for 22mm watch straps with no loops. Visible machining marks. Grade 5 titanium.
Watch strap
Ecopell Enzian leather strap handmade by Sabina Brägger.
Crystal
Saphirglas.
Superluminova in blue
RC TRITEC in Teufen / Switzerland, application by Monyco in La Chaux-de-Fonds / Switzerland.
Swiss Made
The ochs und junior moon phase watch is entirely manufactured in Switzerland. Each watch is hand-assembled and regulated at the ochs und junior workshop in La Chaux-de-Fonds.
Warranty
Two years.
Design
Ludwig Oechslin.