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FAQ
Sun Clock divides the year into eight phases of increasing and decreasing daylight. These “light seasons” are calculated astronomically and shift slightly from year to year.
The moon calendar counts nights instead of days and follows the actual lunar cycle. For details see:
Temporal hours divide daylight and night into twelve equal parts each. Because the length of day and night changes throughout the year, the length of these hours changes as well.
This was a common way of measuring time before mechanical clocks standardized the hour. See also:
In Sun Clock, temporal hours are shown on a 0.0–11.9 scale. The value is a running counter where the integer marks the most recently completed (announced) temporal hour, and the decimal part shows progress towards the next announcement in tenths.
Historically, hour numbers were commonly announced (called out publicly) only once the hour had completed. With this logic, “the sixth hour” refers to the moment the counter reaches 6.0. In Sun Clock this means: the sixth temporal hour begins at 5.1 and is announced at 6.0. After that, values 6.1–6.9 describe the approach towards 7.0.
The additional hint (≈ ¼7, ½7, ¾7) is an orientation aid that uses “towards the next hour” wording. It names the upcoming hour (here: 7) and expresses how far you are on the way to it. This is the same counting logic still used in German dialects (and in Russian): “half three” means 14:30, “quarter three” means 14:15, and “three quarters three” means 14:45 — all referencing the approach towards completion of the next hour (“three”).
So “6.2ἡ ≈ ¼7” means: you are a short way past 6.0 and roughly a quarter of the way from 6.0 to 7.0 (rounded to the nearest familiar fraction).
Gordon’s Sun Clock is designed to work completely offline.
The app contains:
- the Python runtime and the Kivy framework (via Python-for-Android)
- astronomical calculation libraries (Skyfield, NumPy, jplephem)
- the JPL planetary ephemeris DE440s excerpt
- global timezone geometry data (timezonefinder)
- high-resolution images of the planets
- several font sets
Because of this, the app does not depend on external servers or internet access once installed and runs completely offline (except for additional functionality like local weather).
Yes. If you face south (on the northern hemisphere) and hold the device in front of you, the sky on the dial corresponds to the real sky.
Objects that appear higher on the screen are higher above the horizon. Objects on the left are to the left of you, and objects on the right are to the right of you.
The dial shows the sky as a cylindrical silhouette. Because a 3-D sky is mapped onto a flat screen, distances near the left and right edges appear compressed compared to reality.