4 ms·
That explanation is worded somewhat backwards as for cause and effect. It's not that the moon being closer caused the day to be shorter. It's that if we extra
by vikingerik 4y ago
That explanation is worded somewhat backwards as for cause and effect.
It's not that the moon being closer caused the day to be shorter. It's that if we extrapolate backwards from the current values of the day length and the rate of slowing, we calculate that the day must have been 17 hours back then. The cause-and-effect is that the 17-hour rotational period became 24 hours by tidal deceleration.
Other posts have given the cause - conservation of angular momentum in the Earth-Moon system. Angular momentum transfers from the Earth's rotation to the Moon's orbit.
If what you're concerned about is the magnitude of the effect, that's pretty well explainable - the planet now rotates 25% slower when the moon is 25% farther.