Gravitational Acceleration of Spinning Bodies From Lunar Laser Ranging Measurements

TL;DR

This paper reports precise measurements of the Sun's relativistic gravitational effects on Earth and Moon using lunar laser ranging, revealing subtle accelerations that influence the Earth-Moon system's internal dynamics.

Contribution

It provides the first detailed measurement of the Sun's relativistic gravitational gradient effects on spinning bodies within the Earth-Moon system using decades of lunar laser ranging data.

Findings

Measured a 5 cm oscillation in Earth-Moon range due to relativistic effects.

Detected the spin-orbit force's influence on the system's internal dynamics.

Achieved 4 mm measurement precision over 30 years.

Abstract

The Sun's relativistic gravitational gradient accelerations of Earth and Moon, dependent on the motions of the latter bodies, act upon the system's internal angular momentum. This spin-orbit force (which plays a part in determining the gravity wave signal templates for astrophysical sources) slightly accelerates the Earth-Moon system as a whole, but it more robustly perturbs that system's internal dynamics with a 5 cm, synodically oscillating range contribution which is presently measured to 4 mm precision by more than three decades of lunar laser ranging.