Bob Moler's Ephemeris Blog

Ephemeris for Monday, September 23rd.  The sun will rise at 7:31.  It’ll be up for 12 hours and 6 minutes, setting at 7:37.   The moon, 3 days before last quarter, will rise at 9:57 this evening.

The moon has two motions, as I see it in the sky.  As the earth rotates, it appears to carry the moon and all the other celestial objects westward each day and night.  It so happens that the earth rotates one degree in 4 minutes.  The moon and sun happen to be about a half degree in size, so the will appear to move their diameters in 2 minutes.  Since around here they rise and set at a 45 degree angle, more or less, the rising and setting of the moon and sun take about 3 minutes.  The moon also orbits the earth.  It’s orbital velocity is about 2,000 miles an hour.  And since the moon is 2,160 miles in diameter,  its orbital velocity moves it about its diameter in an hour against the stars.  That’s why central solar eclipses last about 2 hours, One hour in and one hour out.

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

Addendum

The 1 hour motion of the moon as it orbits the earth. This is for September 23, 2013. Created using Cartes duCiel (Sky Charts).