Excitation of Lunar Eccentricity by Planetary Resonances
Matija
uk
The origin of the Moon's nonnegligible orbital eccentricity
of 0.053 has no theoretical explanation. Lunar laser ranging
indicates that tides on Earth are currently increasing the Moon's
eccentricity. However, ocean tides were likely much weaker during
the first billion years, allowing lunar tides to damp any primordial
lunar eccentricity very early on. During the tidally driven
expansion of its orbit, the Moon must have been affected by
two substantial resonances related to Jupiter and Venus, passage
through which may have generated today's lunar eccentricity.
Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada.