The rule of time outside the Earth—as example of the time keeping and time service on the Moon

How to unify time outside the earth, from the point of view of relative time, using the two concepts of proper time and coordinate time in relativity, to combine time and space. The physical significance of the simultaneity compensation term in the resolution formula of the International Astronomical Union is analyzed, and the projection relationship of the meridian equivalent simultaneous plane contained in the compensation term is illustrated. There are three different forms of the moon’s center of mass coordinate system, which have different axes orient and different rotational motions. Only in the Frenet coordinate system are there symmetrical and conserved laws of physics, and simple conversion coefficients that relate the proper time to the coordinate time. We define lunar standard time at the origin of the Frenet coordinate system, not on a equipotential surface, and only the coordinate time at the origin are recognized and unique. Let multiple timekeeping devices measure their respective local proper times. Converter this proper time to coordinate time like as the origin, and compare the origin coordinate time pairwise. Save the two-dimensional data table of the clock difference, and check out one which the rate of change in clock difference is the largest, to adjust its conversion coefficients of coordinate time. Select the timekeeping device with the largest deviation from the average value, to adjust its ephemeris. When the clock difference converges within a specified range, the coordinate origin can be agreed upon, achieving uniformity in coordinate time. There are three basic principles: (i) traceability; (ii) four-dimensional space-time simultaneity; (iii) conventionality.