Astrocartography: planetary lines on the world map

Astrocartography is a technique that takes one birth chart and shows it on a map of the world: for every planet it marks the places where, at the moment of birth, that planet stood on one of the four angles of the chart. The method was developed by the American astrologer Jim Lewis in the 1970s under the name Astro*Carto*Graphy, or A*C*G, which is his trademark; astrocartography is the general name for the technique. The planets, signs and aspects in the chart do not change from place to place. What changes is which planets sit on the angles, and astrocartography draws that as lines.

The four angles and the angular planet

Every chart has four angles, the points where the horizon and the meridian cross the ecliptic. Each one has its own area of life in the tradition:

• Ascendant (AC), the eastern horizon: the self, the body, manner, personal initiative.
• Descendant (DC), the western horizon: partners, agreements, the people you meet.
• Midheaven (MC), the upper meridian: work, reputation, public life, achievement.
• Imum Coeli (IC), the lower meridian: home, family, roots, private life.

Each planet page covers its four lines one by one, for example the Mars AC line, the Venus DC line, the Saturn MC line or the Moon IC line.

A planet sitting on or close to an angle is called angular. Astrologers have long treated angular planets as the most visible in a chart: their themes come to the surface and are hard to ignore. A planet that is quiet in the birth chart, tucked away in the middle of a house, can become angular in another part of the world. Astrocartography answers a simple question for each planet: where on Earth would this planet have been on an angle at the moment I was born?

How the lines are drawn

At the moment of birth each planet culminates over exactly one meridian, the line of longitude where it stands on the upper meridian. That meridian is the planet's MC line. The meridian on the opposite side of the globe, 180° of longitude away, is its IC line, where the planet is on the lower meridian. Both run straight from pole to pole, so on a flat map they appear as vertical lines.

The AC and DC lines mark the places where the planet was rising or setting at that moment. They are curves. At the equator the AC line lies 90° of longitude west of the MC line of the same planet, and the DC line 90° east. Take a made-up example: if a planet's MC line runs along 30° East, close to the meridian of Kyiv, its IC line runs along 150° West, and at the equator its AC line crosses 60° West and its DC line 120° East.

Away from the equator the curves bend, and toward the poles they bend sharply. Beyond latitude 90° minus the planet's declination the planet neither rises nor sets, and the AC and DC curves join there. Say the planet's declination at birth was 20° north. North of 70° it stayed above the horizon all day, south of 70° South it never rose, and neither zone has AC or DC lines. In the north the two curves bend toward each other and meet on the planet's IC line at 70° North, where the planet only touches the horizon at its lowest point. In the south they meet on its MC line at 70° South. With a southern declination it is the other way round: the curves join on the MC line in the north and on the IC line in the south.

The tool in the app draws lines between 85° North and 85° South. The point where the curves join is therefore visible on the map for planets with a declination above 5°.

The tool calculates the lines from the planet's right ascension and declination, that is, from its position in the sky (in mundo). Some maps are built from the zodiac degree instead, and for bodies with noticeable ecliptic latitude the two diverge: the Moon can be up to about 5° from the ecliptic, Venus near inferior conjunction up to about 8°, Pluto up to about 17°.

The zone of influence

There is no agreed standard for how far a line reaches. The usual view is that the effect is strongest right on the line and fades with distance. A band a few hundred kilometres wide on either side is often treated as noticeable. When you click on the map in the app, it lists the lines within about 4° of the point, which at mid-latitudes is several hundred kilometres.

Distance on the ground depends on latitude, because meridians converge toward the poles. One degree of longitude is about 111 km at the equator, about 71 km at latitude 50°, where Kyiv, Kharkiv and Prague lie, and about 56 km at 60°. A place 2° of longitude from a vertical MC line is about 220 km from it at the equator and about 140 km from it in Central Europe. Time spent there counts too: a few days near a line and years of living on it are read differently, and the longer you stay, the more the line's themes weigh.

Parans and line crossings

Where two lines of different planets cross on the map, both planets were on angles at the same moment for that spot: one rising while the other culminates, for example. This is called a paran, from the Greek paranatellonta, "rising together". On the map it is a single point, but by tradition a paran acts along the whole latitude of that point, not only at the crossing itself. So a crossing over the ocean can still matter for a city on the same parallel thousands of kilometres away.

Crossings are read with the same logic as aspects in a chart: which two planetary functions meet and on which angles. When two planets already form a conjunction in the birth chart, their lines run close together; with an opposition, the MC line of one falls almost on the IC line of the other. Then the map simply repeats what the chart already shows. A crossing between planets with no natal contact is worth a closer look.

Birth time accuracy

The Earth turns 1° every 4 minutes. A birth time that is off by 4 minutes turns every line on the map together by the same 1° of longitude, east or west. At latitude 50° that is about 71 km. An error of 20 minutes shifts the lines by 5°, about 355 km at the same latitude, which is enough to move a line into a neighbouring region. The AC and DC curves move by the same degrees of longitude, and the distance between the lines of two planets does not change. Near their ends, though, the curves run almost east-west, and there the same change of longitude moves the point where a curve crosses a given meridian a long way north or south.

This makes astrocartography one of the techniques most sensitive to birth time. A time from a birth certificate or hospital record gives usable lines. A time remembered as "around noon" makes them unusable, and a time with a Rodden rating of C or DD (unverified or conflicting sources) makes them doubtful.

The relocated chart

A relocated chart is the same minute of birth recalculated for a different place. The planets, signs and aspects stay exactly as they are; the house cusps and the angles change. A planetary line means that in the relocated chart for that place the planet sits exactly on the corresponding angle. A point on your Venus MC line is a place where, in the relocated chart, Venus is on the Midheaven.

The map and the relocated chart are two views of the same calculation. The map shows where the angular planets are across the whole world at once. The relocated chart shows one place in full detail, including the planets that are near the angles but not on them and the houses that the other planets move into. How to calculate and read it is covered on the relocated chart page.

What the method does not promise

Astrocartography describes which parts of the birth chart are emphasised in a given place. It does not change the chart itself: you carry the same planets and aspects wherever you go, and a planet that is under strain in the birth chart stays under strain on its own line. Before reading a line, astrologers look at what the planet does in the natal chart, its aspects and its condition.

The map is a description, not a guarantee. It does not pick a city, does not promise money, love or success in a place, and does not account for the things that actually shape a move: language, work, people, climate, timing in your life. A line shows which theme comes forward in a place, not how a particular life there will turn out.

The planets on the map

Each planet has its own page with the meaning of its four lines and what sets those lines apart.

• Sun: identity and recognition.
• Moon: home and emotional needs.
• Mercury: speech and contacts; lines that stay close to the Sun's.
• Venus: relationships and taste.
• Mars: drive and competition.
• Jupiter: growth.
• Saturn: structure and long work.
• Uranus: independence.
• Neptune: imagination and blurred boundaries.
• Pluto: depth and transformation.

Open your astrocartography map