Calculations done by British astronomer Dave Waltham demonstrate, however, that Earth’s rotation axis tilt would still be stable if the Moon were only half as massive as it is.[4] A less massive Moon would be smaller in the night sky and thus less disturbing to astronomers’ attempts to study distant galaxies and quasars. Waltham also demonstrated, though, that unless the Moon is as massive as it is, its gravity would be insufficient to have slowed Earth’s rotation rate to the twenty-four hours per day that human life and civilization require.[5] If days were longer than twenty-four hours,
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