Soul Cartography research

Solar vs Lunar Human Design

Credit where it's due: the lunar (Moonlight) chart, the Lunar Incarnation Cross, the lunar synthesis and the Bearing are NightNight Charts' methods. Our engine runs them, and this page shows our working.

The short answer: Solar Human Design is just the standard chart: the Sun sets your Profile, your Earth point and two of your Variables. Lunar Human Design, NightNight Charts' extension, reads those same points from the Moon, and it isn't part of standard Human Design. Same birth, same two moments, and we compute both. Which one leads depends on whether the Sun was above the horizon when you were born. That weighting is a convention we picked, not a discovery.

One birth, two readings

Both charts use the same ephemeris, the same birth moment and the same Design moment, when the Sun stood 88° behind its birth position. Every planet keeps its gate. The difference is which light the derived points are read from.

Profile: the two Sun lines in the solar chart; the two Moon lines in the lunar chart, read as a Nocturnal Line Signature.
Earth: opposite the Sun in the solar chart; opposite the Moon in the lunar chart.
Type, Authority and definition: standard in the solar chart; recomputed from the changed gates in the lunar chart, so they can differ.
Incarnation Cross: a standard cross in the solar chart; a Lunar Incarnation Cross, with NightNight Charts' names, in the lunar chart.
Variables: Digestion and Motivation from the Sun in one and the Moon in the other. Environment and Perspective, read from the Nodes, are the same in both.

The tradition: Only the solar chart is standard Human Design. Nobody in Human Design calls it solar: there's one chart per birth, and this is it. We only use the word to tell the two apart.

Day and night: how the lead is decided

We classify a birth as day or night from the altitude of the Sun's centre at the birthplace at the moment of birth, measured against a flat 0° horizon with no correction for atmospheric refraction. Below the horizon is a night birth. We measure this directly rather than inferring it from the Sun's house, because the two can disagree for births near sunrise or sunset.

If the Sun was within 1° of the horizon, the result is reported but flagged as sensitive. If you give a range for your birth time and the Sun crosses the horizon inside it, sect is reported as uncertain, with both ends shown, rather than settled by picking the middle.

The tradition: Sect, the division of charts into day and night by whether the Sun is above or below the horizon, comes from traditional astrology. Using it to choose between two Human Design charts is our step.

How the two are weighted

When we read the two charts together, a night birth is read 70% lunar and 30% solar, a day birth the other way round, and an uncertain birth 50/50. The weighting decides order, space and which findings come first. It never averages two gates or two Types, because an averaged chart would describe a birth that never happened.

The joint reading does not merge the charts. It describes what lies between them in six kinds of finding: shared ground, echo, recurring theme, polarity, emergence and release. Each finding names the activations it rests on.

Soul Cartography: The 70/30 split is an interpretive convention we chose. Nothing in astrology, in Human Design or in our data fixes those numbers.

What we've tested, and what we haven't

We studied 20,000 births, sampled evenly across 1940 to 2010 and across inhabited latitudes, using the lunar Gene Keys profile built from the lunar chart. Each measurement was repeated against a shuffled baseline, in which each chart's lunar positions came from a different birth. Lunar positions linked to the rest of a chart no more often than chance, by day or by night. About half of all charts have a channel completed by a lunar-only position, so having one is a feature of a chart, not a sign of anything rare.

What that study can't tell us: whether people born at night recognise themselves more in the lunar chart. That's a question about lived experience, not chart structure, and we haven't measured it yet.

The method

The current method

Compute the standard chart first and return it unchanged; build the lunar chart from a copy of its activations.
Classify sect from the geometric altitude of the Sun's centre at the birthplace (0° horizon, no refraction), and flag births within 1° of the horizon.
Given a birth-time range, check the Sun's altitude at both ends; if they fall on opposite sides of the horizon, report sect as uncertain.
Weight a joint reading 70/30 toward the light of the sect, or 50/50 when sect is uncertain, applied to order and emphasis only.
Report every difference between the charts (Type, Authority, Strategy, definition, line pair, centres, channels and gates) with the rule that produced it.

Why we do it this way

Leading with the standard chart keeps the established system as the baseline, so the lunar chart reads as a comparison rather than a correction.
Measuring the horizon directly answers the day or night question itself. House cusps are a calculation that can disagree with it for births near sunrise and sunset.
Weighting order rather than values keeps both charts intact. Averaging would produce gates and Types that neither chart contains.

What it assumes

That sect, a concept from traditional astrology, is a reasonable way to decide which Human Design chart to lead with.
That the geometric horizon, without refraction, is the right boundary. The usual visible-sunrise convention (about −0.83°) would reclassify a thin band of births.
That the birth time is accurate to within a few minutes for births near the horizon.

What is still experimental

The lunar chart itself, and every reading built from both charts together.
The 70/30 and 50/50 weights.
The six kinds of finding and the texts that describe them, which we wrote.

What would change or falsify it

If people born at night recognise the solar chart as readily as the lunar one, leading with the lunar chart for night births is not justified.
If a different horizon convention matched readers' experience better for births near sunrise or sunset, the sect rule would change. The engine stores the refracted altitude beside the geometric one so this can be checked.
Chart geometry already gives the weighting no support. If readers' experience showed no difference either, the weighting would rest on convention alone, and we would say so.

Where it lives

The order of calculation (standard chart first, then sect, the Design interval and the lunar chart): identityos-engine, packages/identityos-nocturnal, the service module.
The altitude rule, the 1° flag and the uncertainty bounds: identityos-engine, packages/identityos-nocturnal, the sect module.
The rule-by-rule difference and the 70/30 joint reading: identityos-engine, packages/identityos-nocturnal, the compare and synthesis modules.
The 20,000-birth shuffled-baseline study, with its data and the script that reproduces it: identityos-engine, docs/research, the unified Gene Keys study.

Common questions

Is the solar chart the same as my normal Human Design chart?

Yes. It is the standard chart, calculated the standard way. We call it solar only to tell it apart from the lunar one.

Is solar vs lunar a recognised distinction in Human Design?

No. Standard Human Design has one chart per birth. The lunar chart is NightNight Charts' method; day and night births come from traditional astrology's sect.

Which one is the real me?

Neither one gets to claim that. The solar chart is the established system; the lunar chart is NightNight Charts' experimental extension. Read both and notice which one sounds like you.

I don't know my birth time exactly. Does that matter?

Yes, more here than elsewhere. Moon lines and the day or night classification can change within minutes. If you give a range that crosses the horizon, sect is reported as uncertain and the two charts are weighted equally.