Home > Constellations, Ephemeris Program, Summer Solstice > 02/18/2014 – Ephemeris – Gemini and the summer solstice

02/18/2014 – Ephemeris – Gemini and the summer solstice

February 18, 2014

Ephemeris for Tuesday, February 18th.  The sun will rise at 7:38.  It’ll be up for 10 hours and 37 minutes, setting at 6:15.   The moon, half way from full to last quarter, will rise at 10:19 this evening.

The constellation Gemini lies above and left of Orion in the southern evening sky.  Jupiter is now seen against its stars.  Gemini is called the twins and its head stars at the upper left of the constellation are Castor and Pollux.  Pollux is to the lower left of Castor.  Stick figures of the lads can be seen extending to the lower right of these stars.  Currently the place in the sky where the sun is on the winter solstice is just to the right of Castor’s big toe.  So it would seem that the sun is entering Gemini on the first day of summer, not Cancer as the astrologers would tell you.  That solstice point is moving westward at one degree every 71.6 years, a motion called precession.  I checked two astronomy programs and that point has now moved into Taurus the bull.

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


Gemini and the summer solstice

The constellation Gemini and the summer solstice point in the sky. Created using Stellarium.

The summer solstice point in the sky is the intersection of the ecliptic, the suns path in the sky and the 6 hour line of right ascension which is like longitude on the earth.  The other blue lines are lines are lines of declination which is like latitude in the sky.  Note also that the summer solstice point is the point on the ecliptic closest to the blue declination line which is the 25º north declination line.  It’s at approximately 23½º north declination, right over the earth’s 23½º north latitude line also known as the Tropic of Cancer.

Back a couple of thousand of years ago the sun was entering the constellation of Cancer, off our image to the left, on the first day of summer.  Since then the summer solstice point has moved westward against the stars at one degree every 71.6 years.  This is due to what is called general precession, of the slow wobble of the earth’s axis caused by the  pull of the Moon and Sun on the Earth’s equatorial bulge.  This torques the earth and causes the 26,000 year wobble, like a spinning top.  Since back then the solstice point passed all the way across Gemini and in 1989 entered the territory of Taurus.

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