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Calculation of lunar orbit anomaly

Louise Riofrio

Author Affiliations

2004 San Sebastian Court, Houston, USA

Planetary Science 2012, 1:1  doi:10.1186/2191-2521-1-1

Published: 20 April 2012



Studies of the Moon, with thanks to NASA and Johnson Space Center, have quantified an anomaly in measurements of lunar orbital evolution. This finding may have significance for cosmology and the speed of light. The Lunar Laser Ranging Experiment from Apollo reports the Moon’s semimajor axis increasing at a rate of 3.82 ± .07 cm/yr, anomalously high.


Sedimentary data indicates a rate of only 2.9 ± 0.6 cm/yr. From historical eclipse records we can accurately calculate a rate of 2.82 ± .08 cm/yr. A detailed numerical simulation of lunar orbital evolution predicts 2.91 cm/yr. LLRE’s laser light differs from independent experiments by up to 12σ.


Several possible explanations are considered. The author’s hypothesis proposes that the speed of light decreases at rate ċ/c = − 0.24 × 10− 10yr− 1. This predicts that LLRE will differ by 0.935cm/yr, precisely accounting for the lunar anomaly.

Cosmology; Laser ranging; Lunar orbit; Relativity; Speed of light