Bob Moler's Ephemeris Blog

Ephemeris for Thursday, September 20th.  The sun will rise at 7:27.  It’ll be up for 12 hours and 14 minutes, setting at 7:42.   The moon, 2 days before first quarter, will set at 10:29 this evening.

The moon and the earth gravitationally attract each other.  And the moon raises tides in the earth itself and its oceans.  The earth’s tides on the mass of the moon has slowed its rotation so it continually shows the earth the same face.  The moon, only one 81st the mass of the earth hasn’t been as successful at slowing the earth’s rotation.  It caused the world’s timekeepers to add one second this June to the time stream after several years to match our atomic clocks to the earth’s rotation.  The most noticeable effects of the moons tidal force is the tides in the earth’s oceans.  The highest tides are when the sun and moon are in line at new and full moon.  Small bodies of water like the Great Lakes don’t have luni-solar tides.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Note

I can’t explain much about tides in one minute.  Here I’m not explaining the force, but am explaining that it affects the solid bodies as well as the oceans on the earth.