Right - I've got a handle on why the Earth wobbles - what I want to know is by how much. The Earth's current axis tilt is about 23 degrees, and this determines the position of the Tropics relative to the Equator. Draw a line from the Sun through the Earth (in plan view) and you'll have two maximum points of wobble, 13,000 years apart. As the Sun goes through its wobble cycle the Tropics will gradually shift. At the Earth's furthest from the Sun point of wobble the Tropics will be further North and South than at the Earth's nearest to the Sun point of wobble when the Tropics will be closer to the Equator. Question is - by how much do the Tropics move 'up and down'?
Oxford blue - "As for your other question - whereabouts in the precession cycle are we now? You can't answer that unless you define where it "starts" and "stops". Your question doesn't really have meaning". OK, I'm sure astronomers have a reference point but let's say the start of the wobble cycle, 0 degrees, is when the North Pole is nearest the Sun. So where in the cycle are we now?