analemma: 6 months worth

Event Date: September 25th
Time: 8:00 AM


Brief

Let's do an analemma update, which I last did near the time of the June solstice.  Now that we are a few days past the September equinox, we are a little over halfway through the astronomical year.  By setting a time and sticking with it every day for a little over 6 months, here are the local-path plots, incremented by 10 days.  The first plot starts on March 19th, being the March equinox and the last being today's date.  The second image is a zoom-in of the same path for the same time duration, showing the plots closer to the summer solstice more defined, being much closer together than those closer to the equinoxes.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   As a reminder, the separation between the plots change with the declination of the Sun.  As the declination rate of change slowed down near the June solstice, it didn't change at all at the second of the solstice.  If I were to change the plot-increment from every 10 days to every day, this would be more noticeable; I refrained from that however, because to magnify the analemma to see all of them at/near the time of the solstice, I wouldn't beable to fit the entire path in the image.  Therefore, try to image it, and remember how many times I have shown the ecliptic and celestial equator together in past images if you are not convinced!  The declination rate changes fastest at the time of the equinoxes, as we notice for where the Sun is; those plots are much further apart.  Whereas near the solstice, the declination change is about 1 degree over a span of about 10 days, it changes by 3 or 4 degrees during that span very near the equinoxes.