Have you ever put a gyro - for instance, a child's toy gyro - down at an angle - say 20 or 30 degrees off the vertical? If you have, you'll know that it's axis describes a rotation about the vertical. The gyro is spinning about its axis at a high rotation rate, but it's whole axis is also rotating slowly with respect to the vertical. Eventually, as the gyro slows down, it falls over, but before that happens, the whole axis rotates with respect to the vertical. The Earth does this as well. The reason is that the equatorial diameter of the Earth is slightly greater than the polar diameter. This gives you an Earth which is slightly fatter in the middle. Therefore the Sun's gravity attracts the Equator more than the Poles, pulling the whole Earth slightly inwards. Given a sideways force, the Earth reacts just like any other gyro - it precesses. And guess what - it's axis rotates just like the child's toy gyro - with respect to the plane of the Earth's orbit round the Sun.
Because the difference between the Earth's polar and equatorial diameter's is quite small and because the Earth rotates quite slowly, the whole precession period is quite long -about once every 25,800 years.
Navigators call this "the precession of the First Point of Aries".
As for your other question - whereabouts in the precession cycle are we just now? You can't answer that unless you define where it "starts" and "stops". Your question doesn't really have meaning.
And yes, there are lots of "real" navigators out there.
Last edited by oxford blue; 1st April 2002 at 17:58.