Earth Rotation Closure
A self-contained exercise for checking the relationship among the native A8 angular ruler, civil clock, Earth-surface navigation distance, mean rotational motion and binary length ladder. No legacy unit is required for the structural proof.
Given
CE,mean is the mean-Earth circumference reference used by the A8 NAV construction.
Exercise A · Angle → Clock
How much rotational time corresponds to one native A8 angular unit?
1 A8 map degree = 4 A8 minutes of Earth rotation
“A8 map degree” here means one native 1/512-turn angular unit, not one legacy 1/360 degree.
Exercise B · Distance → Speed → Time
One native angular-unit arc along the mean-Earth circumference is:
But:
Therefore:
1 A8 angular-unit arc = 64 A8 NAV
Mean rotational motion travels:
Time required to travel 64 NAV:
Cross-check
The angle-and-clock route and the distance-and-speed route were calculated differently. They meet at the same exact result:
Equivalently:
Exercise C · Binary ladder check
Under the current operational A8/31 realization, A8 NAV occupies this position on the binary ladder:
The distance traveled by mean Earth rotation in one A8 SECOND is exactly one quarter of NAV. One quarter is 2⁻², so the ladder position moves exactly two rungs:
The coefficient stays the same. The rung changes by exactly two.
| QUANTITY | EXACT EARTH RELATION | CURRENT A8 LADDER EXPRESSION |
|---|---|---|
| Mean Earth circumference | C | 1.037786960558 A8/56 |
| One A8 angular-unit arc | C / 2⁹ | 1.037786960558 A8/47 |
| One A8 NAV | C / 2¹⁵ | 1.037786960558 A8/41 |
| Rotation distance in 1 A8 SECOND | C / 2¹⁷ | 1.037786960558 A8/39 |
The exponent separations are exact consequences of the definitions. The displayed 1.037786960558 coefficient uses the current operational A8 length realization.
Reverse it
A check should work in both directions. Starting with rotational travel:
Or recover NAV:
Or recover one map-angle arc:
What this confirms
This is an internal mathematical consistency check. It confirms that the A8 angular ruler, day structure, minute structure, NAV definition, mean rotational-speed expression and binary ladder agree with one another.
It is not an independent remeasurement of Earth's circumference: the circumference is an input to the NAV and rotational-distance relationships being cross-checked.