WADOKEI × The World's Smallest Planetarium
An Apple Watch app that merges the traditional Japanese Wa-dokei (Japanese clock) with real-time celestial simulation based on sunrise and sunset.
- 🔴 Red hand (top) — Displays the current time
- ⚪ Center hand — Indicates moon phases and seasons
📸 Screenshots
| Wa-dokei Display | Starry Sky View | Moon & Seasons |
|---|---|---|
 |  |  |
🎬 Demo Video
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▶ Click YouTube(https://www.youtube.com/shorts/JiBH18EU6Xo)
Key Features
🕰️ Traditional Japanese Clock System
- Temporal hour system — divides sunrise-to-sunset into 6 daytime periods, and sunset-to-sunrise into 6 nighttime periods
- 24-hour display synchronized with solar rhythm based on latitude and longitude
- Time expressed in beautiful kanji zodiac characters (Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Sheep, Monkey, Rooster, Dog, Boar)
- Simulation of local solar time and starry skies from locations around the world
- Day/night ring gradient reflecting moon phase and altitude
🌟 Celestial Simulation
- Real-time celestial calculations — accurate sunrise and sunset times for your current location
- Over 1,000 stars and all 88 constellations accurately depicted
- Sun and moon orbits tracked in real time
- Real-time tracking of Venus, Mars, Jupiter, and Saturn
📅 24 Solar Terms Calendar
- Calculates and displays the 24 solar terms based on solar orbital position
- Moon phase display — precisely reproduces phases from new moon to full moon (inverted left/right in the Southern Hemisphere)
- Seasonal hand — turn the crown to simulate seasonal changes throughout the year
About WADOKEI
The ancient Japanese WADOKEI expresses each hour of the day using one of twelve zodiac animals.
| Hour | Animal | Meaning |
|---|---|---|
| 子 | Rat | Midnight — when the Rat is most active |
| 丑 | Ox | Early night — when the Ox is chewing the cud |
| 寅 | Tiger | Late night — when the Tiger prowls for food |
| 卯 | Rabbit | Sunrise — when the Rabbit forages for food |
| 辰 | Dragon | Early morning — when the divine Dragon rises to control the rain |
| 巳 | Snake | Mid-morning — when the Snake becomes active |
| 午 | Horse | Midday — when the Horse cavalry returns from drill |
| 未 | Sheep | Early afternoon — when the Sheep is eating grass |
| 申 | Monkey | Mid-afternoon — when the Monkey hunts for scraps |
| 酉 | Rooster | Late afternoon — when the Rooster returns to roost (= Sunset) |
| 戌 | Dog | Early evening — when the Dog keeps watch |
| 亥 | Boar | Late evening — when the Boar forages in the quiet |
In this app, the hour of 酉 (Rooster) is set to the exact time of sunset.
(Source: wadokei.org)
Apple Watch Controls
Switching Views
- Swipe — Switch between Japanese clock, starry sky, and settings screens
- Double-tap (clock screen) — Toggle between kanji characters and animal illustrations
- Index finger & thumb gesture — Switch between clock and starry sky view (Series 9 and later)
Expanded Starry Sky View
- Starry sky rotates in real time with the electronic compass
- Displays direction and altitude of stars
- Displays positions of the sun and moon
- Turn the crown — Travel through time and observe the night sky
Additional Controls
- Long press — Play a 10-second animation of seasonal changes across the year
Privacy & Security
| Feature | Details |
|---|---|
| Location Data | Used only for astronomical calculations — never transmitted externally |
| Offline Operation | No internet connection required |
| Data Protection | All calculations performed locally on-device |
| Battery Optimization | Efficient algorithms for long-lasting operation |
License
This software uses the following library:
SunCalc
Copyright (c) 2025, Vladimir Agafonkin. All rights reserved.
BSD-2-Clause License
Timeless beauty meets cutting-edge technology.
Would you like to watch a millennium of time on your wrist?