Sunday, November 13, 2011

Is it right?

It goes around Earth once a month and "twirls" on its axis once a month too, so that makes it keep the same side toward Earth. This is not a coincidence. Tidal forces have acted slowly over many millions of years to make the Moon "twirl" at just that speed. The same force is making the rate at which Earth "twirls" (rotates) get slower. That is the reason the world's time services need to add a leap second every so often, to keep the atomic clocks in sync with the slowing rotation rate of Earth.

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