What astrocartography is
Astrocartography (locational astrology) asks a spatial question instead of a temporal one: not 'where is the sky now relative to my chart' but 'where on Earth would my chart have looked different'. For your fixed birth instant, each planet sits on the local Ascendant along one curved line of the globe, on the Midheaven (upper meridian) along another, and on their opposites (Descendant and IC) along two more. Ten planets times four angles: forty lines that partition the world into regions with, traditionally, different flavours.
The astronomy behind the lines is exact and elementary — it is the same sidereal-time and horizon geometry every chart uses, just solved backwards for geographic position instead of time. What is traditional rather than scientific is the reading: 'living on a Venus line makes relationships easier' is a claim about symbolism, not a testable prediction.
How the lines are computed
At your birth instant the Earth has a fixed orientation: we take Greenwich sidereal time and each planet's ecliptic longitude from sub-arcsecond astronomy (VSOP87/ELP via astronomy-engine). For every latitude from 80°S to 80°N we solve which geographic longitude would place your Ascendant (or MC, Descendant, IC — the antiscian mirror comes free by adding 180°) at that planet's degree, inverting the standard horizon equations numerically to well under a degree of error.
MC and IC lines come out as straight meridians, because the midheaven's longitude depends on sidereal time alone, not latitude — one of the useful sanity checks of a correct implementation. Ascendant and Descendant lines curve, steepening toward the poles, and some planet-and-latitude combinations have no solution (the point never rises there), which is why a line can simply stop. The map renders in equirectangular projection over Natural Earth 110m coastlines and clips cleanly at the antimeridian.
What you get
Once your birth data is entered:
- An interactive world map with all forty lines, filterable by planet and by angle family (ASC / MC / DESC / IC).
- A place search that ranks which lines run nearest any city or town, with the distance in degrees.
- A relocation chart for that place: your natal planets re-housed against the new horizon, planet by planet.
- A short traditional reading of each hit — what an Ascendant-line or MC-line is said to colour there.
How to read the map without over-reading it
The conventional vocabulary: a planet on your local Ascendant is read as that planet made personal — the place pulls that energy into your identity and daily visibility; on the MC it is read as made public — career, reputation, being seen. The Descendant and IC versions turn the same theme toward relationships and home respectively. Most practitioners suggest weighing a move by which lines run closest to the destination and by whether the relocated chart (your planets in the new houses) puts anything important angular.
A discipline that keeps this honest: use the map as a vocabulary for places, not a promise from them. A Jupiter-Ascendant city does not come with bundled good fortune; at its best the framework gives language to why somewhere already feels like it fits. Cross-checking with the relocation chart — where the houses genuinely shift — is the substantive part.
A worked example, with real numbers
For a birth at 17:30 UTC on 1 January 2000 in London, the forty lines land in interesting places: New York sits about 5.6° from the Jupiter Ascendant line and 5.9° from the Saturn Ascendant line — a traditionally double-edged address, expansion and responsibility on the same horizon — with the Sun's Midheaven line passing roughly 7.7° away. Tokyo, meanwhile, lies near the Moon's Ascendant line (≈7.7°) and the Saturn Descendant (≈6.4°).
Back at home, London itself turns out to sit ≈5.6° from this chart's Neptune Descendant line and nowhere near a personal-planet angle — a concrete illustration of the central claim of locational astrology: the same birth instant reads completely differently from different places on the ground.
What this tool does not claim
Line placement is astronomy; 'living near the line changes your life' is not. No controlled study has demonstrated relocation-effect claims, and we present the whole framework as traditional symbolism. The lines are also idealised positions at one instant — they say nothing about who has lived there, visa categories, or housing markets, which are all stronger predictors of how a city will treat you.
Technical honesty notes: lines use the same Porphyry-era horizon geometry as our natal charts, the mean (not true) node is used where shown, and near the poles some solutions genuinely do not exist, so a line ending is data, not a bug.
With an unknown birth time the whole map is drawn for an estimated noon instant and flagged approximate — the lines shift by roughly 15° of longitude per hour of uncertainty, so treat them as a family of nearby positions rather than one curve. Calculations run entirely in your browser. Your birth data is never uploaded, never stored on a server, and never shared.
Astrocartography vs. relocation charts vs. local space
Astrocartography maps the world at your birth instant — which lines run where. A relocation chart does the opposite job: it fixes one place and rebuilds your natal chart's houses against that horizon (this tool includes it, because the two readings are strongest together). Local-space astrology, a third technique, projects your natal planets into compass directions around a single city — 'which neighbourhood is my Venus district' — which needs different math we deliberately haven't shipped yet rather than approximating it here.
Our method in one line
Lines solved numerically from sub-arcsecond astronomy (VSOP87/ELP via astronomy-engine) longitudes against the horizon equation at 4° latitude steps (bisection-refined), rendered over public-domain Natural Earth coastlines; relocation uses Porphyry quadrant houses (whole-sign available on every chart). Reviewed by Dr. Amara Osei, Astronomy Reviewer.
Step by step
- 1
Enter your birth data
Date, time and place — the birth instant is what all forty lines are computed at.
- 2
Draw the lines
The map fills with your planetary lines; toggle planets and angle families to unclutter it.
- 3
Search a place you care about
Any city or town ranks which lines run nearest and how far off they are.
- 4
Read the relocated chart
The same search gives your houses for that place — the shift in angles is where the real information is.
Tip — A line 8° away is close in geographic terms but not 'on the line' — distance matters, and the map shows it honestly.
Frequently asked questions
- How close do I need to live to a line for it to 'count'?
- Traditional practice treats roughly 1° as directly on a line and up to about 5-8° as within its orbit; our ranking marks lines within 6° as hits. Beyond that the geometry still draws a line — you simply sit further from its horizon effect in the traditional telling. Treat the distances as a map-reading skill, not a threshold that makes or breaks a place.
- Why do some lines stop or vanish on the map?
- Near the poles, some planets genuinely never rise or culminate at certain latitudes — the horizon equation has no solution there, so the line simply ends. That is correct astronomy, not missing data. Straight vertical lines are the MC/IC families, which are latitude-independent by construction.
- Does an unknown birth time ruin the map?
- It weakens it substantially: every line slides about 15° of longitude for each hour your assumed time is wrong. The tool flags a noon-estimated chart clearly. If you're considering a serious move using this framework, getting a rectified birth time first matters far more than any line on an estimated chart.
- Can astrology really say a city is good for me?
- The lines are real geometry; the 'good for you' part is traditional symbolism with no controlled evidence behind it. We think the honest use is exactly like a Rorschach with excellent math: a structured way to articulate what you already suspect a place will ask of you. Decisions about moving deserve that conversation, plus practical ones.
- Is my birth data private?
- Calculations run entirely in your browser. Your birth data is never uploaded, never stored on a server, and never shared. Solving forty line families is a few thousand ephemeris calls — all of them happening on your device.
Written by
Elena Marchetti
Founder & Staff Astrologer
Methodology reviewed by
Dr. Amara Osei
Astronomy Reviewer
Published 2026-10-01 · Updated 2026-10-01 · Calculated with sub-arcsecond astronomy (VSOP87/ELP via astronomy-engine)