How close does a line have to be?
Every astrocartography tool answers this, and almost none of them say where their answer came from. Here is the published literature, quoted and converted, and the bands this engine actually operates, each traced to the figure it came from. One of them has no citation, and that one is labelled too.
The published limits disagree by 300 miles
Outer limits in print run from 500 miles to 800 miles, which is 805 km to 1,287 km: a factor of 1.6. Put concretely, a place 1,000 km from one of your lines is a genuine influence under Jim Lewis and nothing at all under Moses Siregar, and both are in print under their own names.
These are outer limits compared against outer limits, which is the only comparison that means anything. Several of these practitioners also publish a tighter radius for where a line is predominant rather than merely present, and setting one author's predominant radius against another's outer limit would manufacture a bigger disagreement than exists.
So a tool that shows you a single number without naming a source has made that choice on your behalf and hidden it. The choice is legitimate. Concealing that a choice was made is not.
What the sources actually say
Graded by how directly attributable a figure is, not by how well known its author is:
- A — Jim Lewis's own published words, the field's originator.
- B — A named practitioner in print, under their own byline.
- C — A vendor's encyclopedia, no individual author.
| Source | In their words | Miles | Kilometres |
|---|---|---|---|
| Jim LewisGrade A. Cyclo*Carto*Graphy handbook, 1982, pp. 6–7 (via Currey) | “up to 700 miles each side of where they pass” | 700 mi | 1,127 km |
| Jim LewisGrade A. Professional Training seminar, 1993, p. 26 (via Siregar) | “700-800 miles either side of the line; that's a huge orb” | 700–800 mi | 1,127 km – 1,287 km |
| Moses Siregar IIIGrade B. The only source grading the whole range rather than quoting one outer limit | “under 150 miles very close; 200-350 miles moderate; 350-500 miles weak though still important; I use something like 500 miles as the outer range” | 500 mi | 805 km |
| Ken IrvingGrade B. Lewis's posthumous co-author (via Currey) | “standard around 300 miles, with a maximum orb of 700 miles in some cases” | 300–700 mi | 483 km – 1,127 km |
| Robert CurreyGrade B. Certified A*C*G Consultant | “within 350 miles … predominant; 700 miles weak, but hard to discern” | 350 mi | 563 km |
| Dale O'Brien & Martin DavisGrade B. in Davis (ed.), From Here to There | “a range of relevance up to 500 miles in either direction” | 500 mi | 805 km |
| Astrodienst AstroWikiGrade C. Vendor encyclopedia, no byline | “around 1000 km either side of this line, although the influence wanes” | 621 mi | 999 km |
Lewis added the caveat that makes a graded scheme necessary rather than optional: the lines are not nearly as strong if you're at the edge than if you're right under the line. An orb is not a wall with an inside and an outside, which is how most calculators present it.
Four bands, and where each one came from
We took Siregar's scheme, because he is the only source who grades the whole range rather than quoting one outer limit, and because his outer limit is the tightest of any source here. Adopting it is the conservative reading of the evidence, not the generous one: this engine claims influence in fewer places than the field's own originator would.
| Band | Threshold | Arithmetic | Source |
|---|---|---|---|
| Under the lineClose enough that the line is the first thing worth saying about the place. This is the only band with no citation behind it, and it is deliberately stricter than every source's innermost figure: Siregar's very close begins at 150 miles, Martin Davis's tight working practice at 150. A band this strict can only ever under-claim, and it is the only band allowed to say under the line, so that is the right direction to err in. | 80 km | — | Ours. No source at this radius, and we say so. |
| PeakThe line is doing real work here. Most of what a reading says about a place is said from inside this band. | 320 km | 200 mi → 320 km | Siregar: the top of his strong band, where moderate begins. |
| BackgroundPresent, and worth naming once, but not the thing that decides how a place reads. | 565 km | 350 mi → 565 km | Siregar's moderate/weak boundary, and the same 350 miles Currey calls predominant. |
| FaintThe tightest outer limit anybody publishes. Past here a reading should say nothing, and ours says nothing. | 805 km | 500 mi → 805 km | Siregar's outer range, and O'Brien & Davis's up to 500 miles in either direction. |
Our innermost band is ours, and we say so
80 km is the only figure on this page with nobody behind it. The research found no authority at that radius. We use it anyway, because it is the only band permitted to say a line runs directly over a place, and that claim should be hard to earn.
It sits strictly inside every source's innermost figure, so it can only ever under-claim. A page that quietly laundered one uncited number in among six cited ones would be worth less than no page at all, so it is in the same table, in the same voice, marked.
Distance is not the only measure
A line's ground distance and a planet's separation from an angle in a chart recast for that place are different quantities, and for any body off the ecliptic they genuinely disagree. Neither is wrong. They answer different questions, and this engine prints both rather than averaging them into one number that means neither.
These bands are Siregar's as well, in degrees:
- Strong to 3° — The planet sits within this many degrees of the angle in a chart recast for the place.
- Moderate to 6° — Present in the relocated chart, and worth naming beside the ground distance.
- Out to 8° — Siregar's stated outer limit: eight degrees at most from any angle in the relocated chart.
No source in the literature ranks one measure above the other, so we invent no precedence rule. Where they disagree, the reading pitches its claim at whichever is weaker.
Common questions
- How close does an astrocartography line have to be to matter?
- There is no single professional answer, and a tool that gives you one without a source has chosen for you. Published outer limits run from 500 to 800 miles, which is 805 to 1,287 km: a place 1,000 km from a line is a genuine influence under one respected practitioner and nothing at all under another. This site uses 805 km, the tightest outer limit anyone in the literature publishes, graded into four bands.
- Why does this site use a tighter orb than Jim Lewis did?
- Lewis published 700 to 800 miles, roughly 1,127 to 1,287 km. We use 805 km. Adopting the tightest published limit is the conservative reading of the evidence rather than the generous one: it means this engine claims influence in fewer places than the field's originator would, never more.
- Where does the 80 km band come from?
- Us, and it is the one figure on this page with no citation. The research found no authority at that radius. It sits strictly inside every source's innermost band, so it can only ever under-claim, and it is the only band permitted to say a line is directly over a place.
- Are orbs measured in miles, kilometres or degrees?
- All three are in use, which is part of why the field is hard to compare. The distance literature is written in miles; this engine works in kilometres, converting at the exact 1 mi = 1.609344 km. Degrees measure something different: how far a planet sits from an angle in a chart recast for the place, banded here at 3, 6 and 8 degrees on Siregar's scheme. Distance and degrees genuinely disagree, and this engine reports both rather than averaging them.
See which bands your own places fall in
The free map draws all forty of your lines and names the band for each one, on exactly the thresholds above. No account, no payment, no email.
Outer limit 805 km, the tightest figure published by anyone in the literature. Past it, a reading says nothing.