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What is precession?
Precession of the equinoxes is a nearly twenty-six thousand year wobble of Earth's axis. What this means to us, individually, is that it takes roughly one full lifetime for the first day of spring to increment one day on our calendar. Naturally, the equinoxes are not the only points moving. The entire seasonal calendar is shifting relative to the yearly calendar. Precession is responsible for the so-called "ages" of the zodiac. The "dawning of the Age of Aquarius" may be upon us, but we will remain in Pisces for at least another century. The coordinates used by astronomers to describe the positions of stars in the sky are based on the position of our sun on the first day of spring (vernal equinox), called the "first point in Aries." That point in the sky, however, is no longer in Aries. It left that constellation roughly two thousand years ago. And because of precession, those coordinates are constantly changing, albeit slowly.
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