Method
How the map is made
This explains what the map does, what it doesn't, and why. Astrocartography is often presented with more certainty than the underlying mathematics supports. Ours is built on published ephemerides and clearly stated conventions. Where the mathematics doesn't support a confident answer, we say so.
What a line is
The chart carries thirteen bodies: the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, Chiron, the North Node, and Lilith. Each can sit on one of four angles at the moment of birth: rising, setting, culminating, and anti-culminating. That is up to 52 planetary lines on a single map.
A line is an exact geometric place on the earth, not a band, and it has no orbof its own. The culminating and anti-culminating lines (MC and IC) are vertical meridians; the rising and setting lines (AC and DC) are horizon curves that close onto the meridian near each body's circumpolar cutoff. Any question of how close is close enough belongs to places, not to the lines.
Lines are drawn in mundo, from each body's true position in the sky including its ecliptic latitude, the convention Jim Lewis established. This matters: a zodiacal projection, which flattens that latitude away and which our own maps used before version four, can misplace a high-latitude body's rising and setting lines by tens of degrees of longitude.
The sky it is drawn from
Positions are tropical and geocentric, computed as apparent places on the true ecliptic and equinox of date, with nutation, light-time, and aberration all applied. In plain terms, where each body actually appeared from the earth at that moment, not a simplified average.
The ephemeris is Skyfield reading a committed excerpt of NASA's JPL DE440 data covering the years 1800 to 2200, with nothing fetched at run time. Chiron is not in DE440, so it ships as a committed table of JPL Horizons state vectors run through the same apparent-place pipeline. The North Node is the true, osculating node; Lilith is the mean Black Moon Lilith, the mean lunar apogee.
The accuracy claim, stated exactly as strong as it is and no stronger: every body agrees with the Swiss Ephemeris reference to within 0.05 degrees (3 arcminutes) of ecliptic longitude across the years 1800 to 2200, and the Ascendant, Midheaven, and house cusps agree within 0.05 degrees for all non-polar latitudes.
From lines to places
A crossing is an exact intersection of two lines, a real point where both are angular at once. A single-line place is different: one line passing within about 100 miles (160 km) of a city of at least 500,000 people, weighted stronger the closer it passes. Those are the two shapes worth a pin.
Whether a line counts as active at a place is an orb question. The default working radius is about 600 miles (965 km), and you can tighten it to about 50 miles (80 km) as a display filter. A pin far from any city, its nearest city beyond about 90 miles (150 km), is marked remote and ranked lower rather than dropped.
Every place is named from the GeoNames dataset as city, region, and country. A small settlement snaps up to a city of at least 50,000 people within about 60 miles (100 km), so the map reads in names people recognize.
The chart behind the line
A line is only as trustworthy as the planet that casts it, so every natal body carries a condition. It is scored from three inputs: essential dignity (a planet in a sign it rules adds, one in detriment or fall subtracts; the modern outer planets count rulership and detriment only, and Chiron, the North Node, and Lilith are held neutral by design), natal aspects (soft aspects from Jupiter or Venus add, hard aspects from Saturn, Mars, or Pluto subtract), and house placement (Placidus houses; angular houses add, the sixth and twelfth subtract).
The result sorts into three tiers: supported, neutral, or challenged. Condition shapes how strongly a line draws, how a place ranks, and which reading a place receives. It does not override sentiment, and the map never puts a number on it.
Sentiment
Alongside condition, every line carries a sentiment: its characteristic tone. A canonical table of 52 entries, the thirteen bodies against the four angles, assigns each pairing one of four tiers: supportive, mixed, challenging, or transformative. It is read from the specific line, not from the planet in general, which is why not every outer-planet line lands in the same tier.
Crossings draw on a richer, seven-word vocabulary that collapses back to those same four tiers for display. Sentiment is the color you see at a glance; the reading is where the tone gets its reasons.
Two to seven people
A couple or group map is built on a composite chart: the circular mean of the participants' planetary positions, body by body, for two to seven people. This is the established midpoint method astrologers have long used for couples, extended to groups with circular statistics so the average behaves sensibly on a wheel.
The honest number here is resultant magnitude, from 0 to 1. One means everyone's version of a planet clusters together, a genuine shared signal; zero means the positions scattered and cancelled. Couples always see their composite lines. For a group of three or more, planets with weak magnitude are gated out of the headline places, and the threshold tightens as the group grows, from roughly 0.49 at three people to about 0.32 at seven. When a signal is too weak, the map says so and leans on the individual lines instead of drawing a confident line over noise.
A participant without a birth time still contributes their planetary positions to the composite average, but casts no individual lines of their own. Composite rising and setting lines draw only when every participant has a time.
When the birth time is soft
Birth time sets how much of the map can honestly be drawn, and there are three cases.
An exact time gives the full map, up to 52 lines.
An approximate time, chosen as morning, afternoon, evening, or night, computes the chart at a representative hour: 9:00, 15:00, 19:00, or 23:00. Every line is then placed as if the birth happened exactly then. Longitude error runs at roughly 15 degrees for every hour the true time is off, and the rising sign and houses may be wrong, so the whole map is flagged as a best estimate. It is never presented as equal to an exact time.
An unknown time draws no lines at all, including the career and home lines on the meridian, because every line type depends on the time of day. The planetary positions, aspects, and sign placements still compute and still feed a composite; the houses and rising sign are set aside. Drawing meridian lines from a noon default was removed on purpose, as something that was confidently wrong.
How a place is read
Clicking any point on the map reads that point against the chart already computed, with nothing recomputed on the fly. A solo map shows every line within about 100 miles of the point; a couple or group map shows the composite activations and each person's nearby lines within the major-line orb.
A reading is conditioned on three things together: the whole natal chart, the specific lines present at the place, and the real place itself. That is the whole promise of the map, that it speaks to your chart and your ground rather than to a keyword.
What the map will not tell you
Some honesty about the edges. Parans, the old technique of two bodies angular at the same latitude, are not computed and not drawn anywhere in the product. The map reads places, not timing; it does not yet tell you when to go.
And the map describes patterns and tendencies, not fate. It is not a substitute for professional advice on medical, financial, legal, relocation, or relationship decisions. Big decisions deserve more inputs than one map.