The chart as geography
Astrocartography redraws a birth chart as a world map. The instant of birth stays fixed while the observer's location varies, and every place where Jupiter would have been exactly on the horizon or exactly on the meridian is joined into a line.
The technique dates to the 1970s and is credited to Jim Lewis, who developed it and gave it the name. It is modern, not ancient, and depends on calculation that was impractical before machines did it. The older principle behind it, that a planet sitting on an angle is emphasised, is standard traditional material.
Four lines, and why they are not alike
The Jupiter MC line follows the longitudes where Jupiter was culminating, at the top of the chart on the upper meridian. The IC line follows those where it was at the lowest point, on the meridian below the horizon. Both are meridians, so on the map they run straight from north to south.
The AC line marks where Jupiter was rising in the east and the DC line where it was setting in the west. These are horizon lines, and the horizon's relationship to the ecliptic changes with latitude, so they curve. At high latitudes the curvature becomes extreme and the lines can swing across many degrees of longitude in a short distance. Nearly every popular article draws all four as if they were the same sort of thing, and the difference matters as soon as you look at a real map north of Scandinavia.
What the tradition reads into Jupiter's lines
Jupiter signifies expansion, teaching, law, travel, belief and generosity. The MC line is read as recognition and standing, work that involves teaching or advising, and opportunities that arrive through reputation. The difficulty named alongside it is overreach, taking on more than can be carried and promising past what can be delivered.
The IC line is read as a settled and expansive private life, and also as complacency. The AC line is described as a place where a person is met as confident and welcome, with excess and overconfidence as the standard caution. The DC line reads through other people, associated with helpful partners, mentors and legal or foreign connections, and with a tendency to lean on others' goodwill.
The overreach reading is the part usually left out of relocation writing, and leaving it out is what turns a Jupiter line into a sales pitch. No line delivers success, and this page makes no claim that moving to one changes anything.
Orb, parans and the honest limit
A line is read as active within a few hundred kilometres. Seven hundred to eight hundred is the figure quoted almost everywhere, and the effect is described as strongest on the line and fading with distance. That orb is a convention of the literature. It was never measured, and different practitioners work with different numbers.
Astrocartography is geometry applied to a symbolic system, and the two parts deserve different treatment. The geometry is exact and computable, which is why the lines can be drawn precisely and why any two programs produce the same map. What a Jupiter line means where it happens to cross a city is convention. Weigh it as interpretation, and do not make a move on the strength of it.
Beyond the lines themselves, parans mark latitudes where two planets are angular at once, and a relocated chart shows how the houses rearrange for a new city, which is a different question from which lines run nearby.
Questions people ask about this
Is the Jupiter line the best line to live on?
That framing comes from relocation marketing rather than from the tradition, which pairs Jupiter with overreach as readily as with opportunity. No line is a promise of an outcome.
What does a Jupiter MC line mean?
It marks where Jupiter was culminating at your birth. It is read as public standing, teaching or advisory work, and recognition, with the noted risk of taking on more than can be delivered.
Why are only two of the four lines straight?
The MC and IC lines lie on meridians, which are fixed circles through the poles, so they draw as straight verticals. The AC and DC lines follow the horizon, whose tilt varies with latitude, so they curve.
What orb applies to a Jupiter line?
Around seven hundred to eight hundred kilometres is the usual convention, strongest on the line. It is a working figure carried through the literature, not a measured boundary.
How old is astrocartography?
It comes from the 1970s and is credited to Jim Lewis. The idea that angular planets are emphasised is much older, but the mapping itself is recent.
Do relocating and drawing lines give the same information?
Not quite. Lines show where planets were angular. A relocated chart shows how all the houses redistribute for a specific city, which includes placements that no line passes near.