What astrocartography actually is
Astrocartography takes a birth chart and redraws it as a map of the world. For any planet and any point on the globe, you can ask a plain question of geometry: at the exact moment of birth, where was that planet relative to the horizon and the meridian as seen from here? Join up every place where the answer is the same, and you have a line.
The technique is modern. Jim Lewis developed and named it in the 1970s, and the maps only became practical once the arithmetic could be done by machine. Older astrology relocated charts by hand for one city at a time. Nothing in the ancient material describes lines drawn across continents, and it is worth saying so plainly rather than letting the technique borrow authority it does not have.
What is genuinely old is the idea behind it, that a planet on an angle is emphasised. Astrocartography just asks where on Earth that emphasis would have fallen.
The four Sun lines and how they differ
The Sun MC line runs through everywhere the Sun was culminating, sitting on the upper meridian directly overhead. The Sun IC line marks the opposite, where it was at the lowest point beneath the chart, on the meridian below. Both of these are straight lines of longitude running north to south, because the meridian is a fixed circle through the poles.
The Sun AC line marks where the Sun was rising on the eastern horizon, and the DC line where it was setting in the west. These two are not straight. The horizon sits at an angle to the ecliptic that changes with latitude, so the rising and setting lines curve, sometimes gently and sometimes very sharply near the poles. Most maps and most articles present all four as though they were the same sort of object. They are not, and knowing which two are meridians and which two are horizon curves explains a lot of otherwise puzzling map behaviour.
What the tradition reads into the Sun's lines
The Sun is read as visibility, identity and the thing a person is taken to be. On the MC line the tradition reads public position, being seen and named, work that carries your face on it. It also reads the cost of that, which is exposure, and a place where being unnoticed is harder than it was at home.
The IC line is read the other way, as roots, home, family and the private base. Some accounts call it restorative and others call it inward to the point of stalling, and both descriptions come from the same symbolism.
The AC line is read as a place where a person comes across strongly and is met on their own terms, with the difficulty being self-absorption or a tendency to take up all the air. The DC line is read through partnership and through other people, either as the place you meet someone significant or as the place where other people define your terms.
None of this predicts an outcome. Moving somewhere does not deliver a result, and this page will not tell you otherwise.
Orb, and how far to trust it
A line is normally read as active for a few hundred kilometres to either side. The figure quoted almost everywhere is about seven hundred to eight hundred kilometres, with the effect described as strongest exactly on the line and fading outward. That number is a convention passed down through the literature, not a measured range, and different practitioners use different values without much argument about it.
The honest position is this. The geometry is exact and computable, which is why a line can be drawn to the kilometre. What that line means where it crosses a particular city is convention, layered on top by people. Both halves are real work, but they are not the same kind of claim, and treating the second with the confidence appropriate to the first is the main mistake in this field.
Two related refinements are worth knowing. Parans are latitudes where two planets are angular at once, giving horizontal bands rather than lines. And relocating a chart changes the house placements of every planet, which is a separate calculation from the lines themselves.
Questions people ask about this
What is a Sun line on an astrocartography map?
It is the set of places where the Sun was on one of the four angles of your chart at the moment of birth. Because there are four angles, there are four separate Sun lines, and they carry different readings.
Why are the MC and IC lines straight but the others curved?
The meridian is a great circle through the poles, so culminating and anti-culminating positions fall along fixed longitudes. The horizon tilts against the ecliptic by an amount that changes with latitude, so rising and setting positions trace curves, which bend hard at high latitudes.
How close do I need to be for a Sun line to count?
The usual convention is within about seven hundred to eight hundred kilometres, strongest on the line itself. Treat that as a working habit rather than a measured boundary, since no observation established it.
Is astrocartography an ancient technique?
No. Jim Lewis developed it in the 1970s. The underlying idea that angular planets are emphasised is much older, but the world maps are recent and depend on computation.
Should I move to my Sun MC line?
That is not a question this page answers. Astrocartography describes a symbolic geography, and no line guarantees an outcome. Practical reasons for moving somewhere deserve more weight than a map.
What is a paran line?
A paran is a latitude at which two planets are simultaneously angular, though not necessarily on the same angle. Parans appear as horizontal bands across the map and are read as a blend of the two planets involved.