Astronomical Theory Section - Planetary Phenomena


The Recession of the Moon  (3)

  • Introduction
    • Basic principles
  • Tidal Dissipation
  • Angular Momentum
  • Energy
  • Interim Summary
  • Evolution of the lunar orbit
    • Conservation of Angular Momentum
    • Tidal Dissipation
    • Conservation of Energy
  • Graphical results
  • Variable tidal dissipation
  • Further complications
  • Conclusions
  • The extinction of total solar eclipses
  • Rotational and orbital periods
This article begins by summarising the basic physical processes which are causing the Earth-Moon distance to increase, before discussing the three inter-related factors which together cause this recession to come about. A mathematical treatment of these processes is then developed which allows the evolution of the Moon's orbit over time to be calculated using an integrational method. The results are compared to the timescales deduced from geological studies and a number of improvements to the model are investigated in order to align the model results more closely with the geological record: the most important of these is the incorporation of the effect of continental drift. Two interesting consequences of the variation of the lunar distance are then explored: the changing nature of solar eclipses (and the eventual disappearance of total eclipses), and the change in length of the day and the month.

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