LunaWhy time and place matter
Planets move slowly, so the date alone already shows which sign each of them is in. The ascendant, however — the point rising on the horizon — shifts about one degree every four minutes and travels the whole circle in a day. The houses turn with it: twelve sectors that say which area of life a planet works in.
A chart without a birth time can still be cast, but it will have no ascendant and no houses. One more detail: the Moon crosses a sign in roughly two and a half days, so on a changeover day its sign is uncertain without a time.
What a chart is made of
| Element | What it is | What it speaks about |
|---|---|---|
| Sun | the sign the Sun stood in | the core, what a person moves towards |
| Moon | the sign of the Moon | feelings, what is needed to feel safe |
| Ascendant | the sign rising on the horizon | how a person comes across |
| Mercury, Venus, Mars | personal planets | thinking, love and taste, will and anger |
| Jupiter, Saturn | social planets | growth and support, maturity and limits |
| Uranus, Neptune, Pluto | outer planets | generational themes, deep change |
| Houses (1–12) | sectors of the chart | the area of life where it all plays out |
| Aspects | angles between planets | how the parts of a character get along |
How the chart is actually calculated
Planetary positions do not come from a table on a website but from ephemerides — astronomical data on the motion of celestial bodies. Professional software uses the Swiss Ephemeris; so does our app.
The order of work: the date and time are converted to UTC using the time zone of that place in that era (zones have changed over the years), the longitudes of the planets are computed from the ephemerides, and the coordinates of the city give the ascendant, the MC and the house cusps. Houses are calculated with the Placidus system, the most widely used one.
An aspect counts when the angle between two planets is close enough to exact — within the orb: 6° for conjunction, square, trine and opposition, 8° when the Sun or Moon is involved, 5° for a sextile.
Example: 17 May 1993, Moscow, 12:00
Sun at 26°25′ Taurus, Moon at 8°14′ Aries, ascendant at 22°02′ Leo. These figures match a public astrological calculator down to the arc second: the calculation gives an exact degree rather than “roughly Taurus”, and houses and aspects depend on that degree.
Natal chart and destiny matrix
They are two independent systems and cannot contradict each other: different inputs, different language. The matrix needs only a date and speaks in numbers and arcana about tasks and character. The chart needs time and place and speaks in planets about how a person is built and how they show up. More on the destiny matrix.
Frequently asked questions
Can a natal chart be built without a birth time?
Yes, but it will be incomplete. The planets in signs are still calculated, the ascendant and houses are not: they depend on the time and change through the day. If the Moon changed sign that day, its position is also uncertain.
Where do I find my exact birth time?
It is usually written on the birth certificate or in hospital records. If you only know it approximately, enter the approximate time — the chart will still be more accurate than with no time at all.
Which matters more — Sun, Moon or ascendant?
They answer different questions and work together. The Sun is the core and the direction, the Moon is feeling and the way a person recovers, the ascendant is how they are seen at first meeting.
What does Saturn mean in a chart?
Saturn shows where a person grows up: where things are hard at first and require discipline, the steadiest support eventually appears. It is about maturity and limits, not punishment.
Is astrology a science?
Calculating planetary positions is astronomy, so that part is exact. Interpreting the chart is not: it is a symbolic language for self-reflection, not a scientific method and not a prediction of events.
The content is for entertainment and self-reflection. It is not a substitute for medical, legal or financial advice.
Build your own chart
Luna calculates the chart from real ephemerides and tells you what matters in plain words: Sun, Moon, ascendant and the tightest aspects — without the jargon.
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