How to Read Your Astrocartography Map

Before you start: how good is the birth time?

The map is built from one moment, so its accuracy is the accuracy of the birth time. The Earth turns about one degree every four minutes, and every line on the map slides east or west with it. A later time moves all 40 lines west; an earlier time moves them east. There is no exception for the straight MC and IC lines: a widely repeated claim that they are safer with an uncertain time is wrong, because they move exactly as far as the curved ones.

William's time comes from the official announcement of his birth: 9:03 PM British Summer Time on June 21, 1982, in London. Redrawing his map 15 minutes later moves every line by about 3°44′ of longitude. How far that is on the ground depends on latitude, because the meridians converge toward the poles:

Some birth records give the time to the minute, some give no time at all, and family memory often rounds to the hour or half hour. If your time is uncertain by half an hour, every line on your map could be twice the distances above away from where it is drawn, in either direction. Keep that margin in mind at every later step.

Step 1: Tell the four kinds of line apart

Each line belongs to one planet and one angle. The angle is what changes the meaning, so identify it first. On this site's map every line is labeled at the top and bottom edge with the planet's glyph and the angle, and the angles are drawn differently: the MC solid, the IC in long dashes, the ASC solid and the DSC in short dashes.

• MC lines run straight north and south. Along them the planet's degree was culminating, at the top of the chart.
• IC lines also run straight north and south, always exactly 180° of longitude from the same planet's MC line. William's Jupiter MC line is at 2°03′W; his Jupiter IC line is at 177°56′E, on the far side of the world.
• ASC lines curve. Along them the planet's degree was rising on the eastern horizon.
• DSC lines curve the other way. Along them it was setting in the west; each DSC line is the ASC line turned to the opposite side of the globe.

How much an ASC or DSC line curves depends on the declination of the planet's degree, its distance north or south of the sky's equator. William's Sun, at 0°06′ Cancer, was at the greatest declination the Sun reaches, and its ASC line swings through 51°23′ of longitude between 45°S and 45°N. His Mars, at 9°12′ Libra, was close to the equator of the sky, and its ASC line moves only 7°18′ over the same range. A nearly straight ASC line is not an MC line; check the label.

Step 2: Put your places on the map

Lines matter only where they meet your life, so list the places first: where you live, where you work, where you grew up, where you are thinking of going. Use the city search on the map to pin each one. The pin lists up to five lines within 1,500 km, nearest first, with their distances. On a desktop, hovering anywhere gives the nearest line under the cursor and its distance.

Distances are great-circle kilometers from the place to the nearest point of the line, not to the nearest point drawn at a whole latitude. That difference matters near a line: measured only to the drawn points, a city right on a line could come out more than 25 km away.

On William's map, the card under the map lists the three lines nearest his birthplace: the Neptune ASC line at 116 km, the Jupiter MC line at 130 km and the Sun DSC line at 157 km. The next nearest, the Moon DSC line, is 447 km away, so London has three lines close by and then a clear gap.

Step 3: Decide how close counts

Astrocartographers do not agree on how far a line's influence reaches. Many readers work within a few hundred kilometers, but no published standard fixes the distance, and the graded scales of distance you may see elsewhere are conventions, not measurements.

Two figures from the first section set a sensible lower limit. First, on London's parallel a degree of longitude is 69 km, so a quarter-hour of birth-time doubt is 260 km. Second, a line passing 116 km from a city with a time good to the minute is a firmer reading than one passing much closer to a city whose time was rounded to the hour. Judge distances against your own time, and against latitude: the same longitude gap is 111 km at the equator and 55 km at 60°.

Step 4: Read the angle, then the planet

Each angle sets the subject. The MC concerns work, standing and reputation; the IC home, family and private life; the ASC yourself, your manner and body; the DSC partners and the people you deal with. The planet then says what happens in that area: Jupiter growth and opportunity, Saturn duty and slowness, Venus ease and affection, Mars drive and friction, and so on. Read them in that order and the line becomes a sentence: Jupiter on the MC is growth in your working life.

Then check the planet in your birth chart. Readers weigh a line by how its planet already works for you: a Saturn that is well placed at birth is read more kindly on an angle than a Saturn under pressure. The planet pages linked at the end of this guide give the readings for each planet on each angle.

In William's case the three lines near London give three subjects. His Jupiter MC line runs 1°53′ west of his birthplace, through Birmingham (11 km); a reader would call it his line for public growth. His Neptune ASC line passes London at 116 km and is read for a softened, idealized image. His Sun DSC line, at 157 km, is read for significant partners. None of these is a prediction; they are what the lines are taken to describe.

Step 5: Find crossings and parans

A crossing is the point where two lines meet. On a zodiacal map it always joins one planet's MC or IC line to another planet's ASC or DSC line: two meridians run parallel, and two horizon lines can never meet, because a place has only one Ascendant. Readers treat a crossing as the place where both readings apply together.

A paran is the latitude through a crossing, extended around the globe. Everywhere along it the two planets reach their angles together, not at the birth moment but at some hour of that day. The map groups crossings into bands 1° of latitude wide, about 111 km from north to south, and draws each band when you turn on parans in the filters.

Crossings come in pairs. Opposite any crossing, on the far side of the globe, the same two planets meet on the opposite angles: an MC with ASC crossing at one point has an IC with DSC twin at the antipode. All 74 crossings on William's map come in such pairs. His Jupiter MC line meets his Neptune ASC line at 51°45′N, 2°03′W, 82 km from Birmingham; the twin is the Jupiter IC and Neptune DSC crossing at 51°45′S, 177°56′E.

London itself lies in the 52°00′N band, which holds two crossings: Mercury DSC / Mars MC and Jupiter MC / Neptune ASC. A band can hold crossings that have nothing to do with each other, so read each pair on its own.

Step 6: Confirm with the relocated chart

A relocated chart recasts the birth moment for one place. The planets keep their degrees; the Ascendant, Midheaven and houses change. On a desktop, the map's hover box gives the relocated Ascendant and Midheaven for the point under the cursor, computed exactly for that point. On a zodiacal line, the relocated chart has the planet exactly on the angle, which is a useful check that you are reading the right line.

Hiroshima shows the match: it lies 3 km from William's Sun ASC line, and its relocated Ascendant is 0°08′ Cancer, 0°02′ from the Sun at 0°06′ Cancer. The table also shows what lines alone cannot: with the MC at 0°39′ Scorpio in Birmingham and 29°17′ Libra in Edinburgh, the Midheaven changes sign between two cities on either side of the same line.

Putting it together: one city, start to finish

Take Birmingham on William's map and run the six steps. The birth time is to the minute, so the margin from the first section is small. Pinning the city lists the Jupiter MC line at 11 km and the Neptune ASC line at 44 km, both far inside the 260 km that a quarter hour of doubt would cover. One is a meridian and one a curve, so the subjects are public standing and self-presentation.

Read as angle and planet, that is growth in working life from Jupiter and a softened, idealized image from Neptune. The two lines cross 82 km from the city, and Birmingham, at 52°28′N, sits in the same 52°00′N paran band as the crossing. The relocated chart confirms the reading: the Midheaven is 0°39′ Scorpio with Jupiter 0°09′ short of it, just past culmination, and the Ascendant is 24°48′ Sagittarius with Neptune 0°43′ beyond it, about to rise. A reader would sum up Birmingham on this map as Jupiter at the top of the chart and Neptune on the horizon, each within a degree of its angle, and would then weigh that against everything a map leaves out.

What a map cannot tell you

• It cannot say what will happen. Astrocartography is a symbolic practice, and no study has shown that living on a line changes anyone's life.
• It describes one convention. This site draws zodiacal lines, which ignore how far a planet sits from the ecliptic; maps drawn in mundo, from the planets' true positions, put planets that sit far from the ecliptic, Pluto above all, in different places. The map page gives the differences for William's map.
• It belongs to a moment, not a person. Anyone born at the same instant, anywhere, has the same map.
• It ignores everything practical about a place: climate, work, cost, family and health care weigh more in any real decision.

Within those limits, a map is a structured way to ask what a place emphasizes in a chart. The technique was popularized in the 1970s by Jim Lewis, who mailed hand-drawn Astro*Carto*Graphy maps from 1976; his posthumous book with Kenneth Irving, The Psychology of Astro*Carto*Graphy (1997), sets out his own readings.

Read each planetary line

Each planet page covers its four lines with a worked example, and the astrocartography guide links the angle, goal and crossings pages.

Questions about reading a map