This paper offers a philosophical and conceptual analysis of the ontological status of time, proposing an operational definition grounded in orbital mechanics. We argue that time is neither an autonomous Newtonian absolute nor an Einsteinian elastic dimension, but the cycle counter of a celestial body orbiting its central star — formally T = N × T₀, derivable from Kepler's Third Law with NIST/CODATA 2018 constants. We accept all experimental data from classical tests of relativity (Hafele–Keating, cosmic muons, GPS) but offer a reinterpretation of their ontological significance: these experiments demonstrate that velocity and gravity alter the internal physical processes of measured objects, not local astronomical time as defined by orbital dynamics. We introduce and defend a mechanical criterion for temporal change: local astronomical time changes if and only if the orbital state vector — axial rotation velocity, translational orbital velocity, or orbital distance — is modified. Three sigma-level statistical analyses anchor the argument in precision data: (z₁ = 0.06σ) Earth's orbital period is statistically invariant within IERS measurement precision; (z₂ ~ 100σ) GPS correction and orbital secular variation have physically distinct origins, supporting an instrumental calibration interpretation; (z₃ = 7.3σ) the sole observed secular drift is entirely attributable to lunar tidal deceleration — a direct action on the orbital state vector. We position this proposal in dialogue with Newton, Einstein, Leibniz, Mach, Barbour, and Smolin, arguing that its specific contribution is the first mechanically verifiable operational criterion to define, measure, and alter time.
REGIVALDO DE ALMEIDA (Fri,) studied this question.