What is astrocartography?

The idea in one paragraph

Every planet is directly overhead somewhere on Earth at any given instant. It is also on the eastern horizon along one curve, on the western horizon along another, and directly underfoot on the meridian opposite the first. Freeze those positions at the moment of your birth and draw them, and you have four lines per planet: forty lines for the ten planets.

What astrocartography adds is an interpretation. It reads a place near your Venus line as one where the Venus part of your chart is emphasised, and a place near your Saturn line as one where the Saturn part is. The geometry is exact and uncontroversial. The interpretation is a tradition, and this site is explicit about which is which.

Where it came from

The technique in its current form was developed by the American astrologer Jim Lewis in the 1970s, who trademarked it as Astro*Carto*Graphy and spent two decades popularising it. The underlying astronomy is much older: relocating a chart to a different place is a classical procedure, and the observation that a planet is angular somewhere is as old as the angles themselves.

What Lewis contributed was the map. Plotting the angular positions for every longitude at once turned a calculation you had to run per city into a picture you could read at a glance, and that is why the technique spread.

What a line actually is

A line is not a corridor of influence radiating outward. It is the set of points at which a planet was exactly angular. Everything about proximity is interpretive convention layered on top of an exact geometry.

Two consequences follow, and both are usually left out. First, the four line types are different in kind, not in degree: a Mars MC line and a Mars rising line are not stronger and weaker versions of each other, they are separate statements. Second, the lines are only as good as your birth time. A time rounded to the nearest half hour moves every line by roughly 800 km, which is wider than the strongest interpretive band. The accuracy of your time matters more than the precision of any reading.

What it is useful for

The honest answer is that it is a structured way of thinking about place. People use it when choosing where to travel, where to work for a year, or where to consider moving, and its practical value is that it makes you articulate what you are actually looking for from a move.

What it is not is a decision procedure. Nobody should move country because a line runs through it, and this site says so on the tool itself rather than in the small print. Visa status, work, language, cost and the people you would be leaving are all better predictors of whether a move goes well.

Frequently asked questions

Is astrocartography accurate?

The geometry is exact and reproducible: the lines are computed from the Swiss Ephemeris and any competent implementation will draw them in the same place. Whether the interpretation attached to a line holds is a separate question, and not one that has been tested in any controlled way.

How close do you have to be to a line for it to count?

Convention treats about 120 km as fully in effect and about 240 km as still present, with nothing worth saying past roughly 650 km. Those are the bands this site publishes and uses. Bear in mind that an imprecise birth time can shift a line further than the widest band.

Do I need my exact birth time?

Yes, more than for almost any other technique. Astrocartography depends on the angles, which move roughly one degree every four minutes. Without a reliable time the map is not meaningfully yours.