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The solstice is the point were Earth’s axis points
toward or away from the sun (toward or away
depending on which hemisphere you’re in). Now if
this direction of tilt changes (precesses), the points
of solstice and equinox move as shown in Firgure 7:
Figure 7 Right: Precession moves solstices and equinoxes clockwise.
As the solstices and equinoxes mark the seasons, the
seasons move, rotating clockwise. Figure 8 shows
the seasons, equinoxes, and solstices rotated clockwise. Imagine precession as all of these orbit elements rotating clockwise, for a complete loop every
26,000 years.
Figure 8: Seasons shown as a
4-color ring moving clockwise
with precession
ICY SCIENCE | QTR 1 2014