Astrology guide
A natal chart is a map of where the Sun, Moon and planets were, seen from the place of birth at the moment of birth, set against the twelve signs of the zodiac and twelve houses. Scryway calculates charts from astronomical data and states every convention it uses. The positions are astronomy; what they are taken to mean is astrology, a symbolic tradition, and is labelled as interpretation throughout.
How positions are calculated
- Charts are calculated with the Swiss Ephemeris (Astrodienst), the standard engine of professional astrology software, using its ephemeris files derived from NASA JPL’s DE441. Positions are apparent geocentric longitudes on the ecliptic of date, the frame astrology uses. Tests compare them with NASA JPL’s Horizons service: every body agrees within two seconds of arc.
- The Swiss Ephemeris runs in Scryway Ephemeris, a separate calculation service. Scryway sends it the moment and place and shows what it returns. The service is free software under the GNU Affero General Public License, and its full source code is public: you may study, run, change and share it. It keeps nothing it is sent.
- If the service cannot be reached, a chart with standard settings is calculated in your browser with astronomy-engine (MIT licence, accurate to about one arcminute), and the chart says so. Settings only the Swiss Ephemeris supports wait for the service instead of being quietly changed.
- Each saved chart records the engine and version, the settings and the exact UTC instant used, so it can be reproduced later.
Birth time and place
- Time zones come from the IANA time-zone database built into your browser, which includes historical changes and daylight saving. If the clock time you enter was skipped (clocks went forward) or happened twice (clocks went back), you are asked rather than guessed for.
- Before standard time (in many places until the late 1800s or early 1900s) the database uses the local mean time of the zone’s main city. You can switch to local mean time for the birthplace itself, or enter an offset; the offset used is shown and saved.
- Places come from GeoNames (towns of about 15,000 people or more) and are searched on Scryway’s own server; nothing is sent to a third-party service. Anywhere else can be entered as coordinates and a time zone.
Unknown and approximate birth times
The Ascendant moves through all twelve signs in a day, and the houses with it, so they depend on an accurate time. With an unknown time, Scryway calculates planets for local noon, leaves out houses and angles, and names any body that changes sign during that day (usually the Moon). With an approximate time, the chart is calculated at the time given, and the range the Ascendant and Midheaven cover over your window is shown, including any change of rising sign. Aspects to the angles are only shown for exact times.
Conventions
- Zodiac:
- Tropical (default): Signs measured from the March equinox. The usual Western convention.
- Sidereal (Lahiri): Signs fixed against the stars, using the Lahiri ayanamsa, the standard in Indian (Vedic) astrology.
- Sidereal (Fagan-Bradley): Signs fixed against the stars, using the ayanamsa of Western sidereal astrology.
- Sidereal (Raman): The ayanamsa of B. V. Raman, used in some Indian astrology.
- Sidereal (Krishnamurti): The ayanamsa of the Krishnamurti Paddhati (KP) system.
- House systems:
- Placidus (default): Divides the time each degree takes to rise and culminate. The most common modern Western default; undefined near and beyond the polar circles.
- Koch: Birthplace houses, based on the Midheaven's semi-arc. Popular in German-speaking astrology; undefined near the poles.
- Regiomontanus: Divides the celestial equator into twelve equal parts. Common in horary astrology.
- Campanus: Divides the prime vertical into twelve equal parts.
- Topocentric: Polich and Page's system, close to Placidus but defined at all latitudes.
- Alcabitius: A medieval system dividing the Ascendant's diurnal arc.
- Morinus: Equal divisions of the equator from the meridian; the Ascendant is not a cusp.
- Porphyry: Each quadrant between the angles is split into three equal parts.
- Equal: Twelve 30° houses measured from the exact Ascendant.
- Whole Sign: Each house is one whole sign, starting with the rising sign. The oldest known system, used in Hellenistic and much Indian astrology.
- Aspects are the five major (Ptolemaic) aspects. Default orbs, which you can change: conjunction 8°, sextile 5°, square 7°, trine 7°, opposition 8°. Orbs vary widely between astrologers.
- Lunar node: Mean node (default): The node's average position, moving steadily backwards. True node: The node's actual position, which wobbles around the mean.
- Chiron is included. Other asteroids, fixed stars and Arabic parts are not yet. The Swiss Ephemeris files used cover 1800 to 2399; for other dates planets fall back to a slightly less precise theory (still accurate to about a second of arc) and Chiron is omitted, with a note on the chart.
Reference: what the parts of a chart mean
Interpretive notes summarise common modern Western readings of each factor, written for Scryway. They are not calculated and are not a personal reading: astrologers weigh a whole chart, and traditions differ.
Planets and points
- ☉︎ Sun (identity, vitality, purpose): The core sense of self and what you are trying to become; where you seek to shine and feel most alive.
- ☽︎ Moon (feeling, needs, habit): Emotional needs, instinctive responses and what makes you feel safe; the private self and your patterns of care.
- ☿︎ Mercury (thinking, speech, learning): How you perceive, think, learn and communicate; curiosity, trade and the exchange of information.
- ♀︎ Venus (attraction, value, harmony): What you love and value, how you relate and attract; taste, pleasure, and the wish for balance and beauty.
- ♂︎ Mars (drive, desire, courage): How you go after what you want: energy, assertion, competition and anger, and the courage to act.
- ♃︎ Jupiter (growth, meaning, generosity): Expansion and opportunity; belief, philosophy, teaching and the search for meaning; also excess.
- ♄︎ Saturn (structure, limits, mastery): Responsibility, discipline and time; where life asks for patience and effort, and where lasting skill is built.
- ♅︎ Uranus (change, freedom, originality): Sudden change and awakening; independence, invention and the urge to break from convention. Discovered 1781.
- ♆︎ Neptune (imagination, ideals, dissolving): Dreams, compassion, spirituality and art; also confusion and illusion, where boundaries blur. Discovered 1846.
- ♇︎ Pluto (power, depth, transformation): Intensity, power and what is hidden; endings that make way for renewal. Discovered 1930.
- ⚷︎ Chiron (wounding, healing, teaching): A small body orbiting between Saturn and Uranus, discovered 1977. Modern astrology reads it as an old hurt and the understanding it can lead to.
- ☊︎ North Node (direction, growth, appetite): Not a body but the point where the Moon's path crosses the ecliptic northward. Modern astrology often reads it as a direction of growth; traditional astrology treats it more simply as a point of increase.
Signs
- ♈︎ Aries: Fire, cardinal, ruled by Mars. initiative, directness, courage.
- ♉︎ Taurus: Earth, fixed, ruled by Venus. steadiness, comfort, persistence.
- ♊︎ Gemini: Air, mutable, ruled by Mercury. curiosity, versatility, conversation.
- ♋︎ Cancer: Water, cardinal, ruled by Moon. care, protection, memory.
- ♌︎ Leo: Fire, fixed, ruled by Sun. expression, warmth, pride.
- ♍︎ Virgo: Earth, mutable, ruled by Mercury. discernment, service, craft.
- ♎︎ Libra: Air, cardinal, ruled by Venus. balance, partnership, fairness.
- ♏︎ Scorpio: Water, fixed, ruled by Mars (traditional); Pluto (modern). depth, intensity, loyalty.
- ♐︎ Sagittarius: Fire, mutable, ruled by Jupiter. exploration, belief, candour.
- ♑︎ Capricorn: Earth, cardinal, ruled by Saturn. ambition, structure, endurance.
- ♒︎ Aquarius: Air, fixed, ruled by Saturn (traditional); Uranus (modern). independence, ideals, community.
- ♓︎ Pisces: Water, mutable, ruled by Jupiter (traditional); Neptune (modern). empathy, imagination, surrender.
Houses
- Self, body, appearance and how you meet the world; the start of things.
- Resources, money, possessions and what you value.
- Communication, siblings and neighbours, short journeys, everyday learning.
- Home, family, roots and private foundations.
- Creativity, pleasure, romance, play and children.
- Daily work, routines, service and health.
- Partnership, marriage, close one-to-one relationships, and open opponents.
- Shared resources, intimacy, debts and inheritances; crisis and change.
- Travel, higher learning, belief, law and publishing.
- Career, reputation, public standing and direction.
- Friends, groups, networks, hopes and aims.
- What is hidden or withdrawn: solitude, retreat, the unconscious, institutions.
Aspects
- ☌︎ Conjunction: Two points together: their meanings blend and act as one, for better or worse.
- ⚹︎ Sextile: 60°: an easy, cooperative link that offers opportunities when used.
- □︎ Square: 90°: friction between two drives; tension that pushes for action and growth.
- △︎ Trine: 120°: a smooth, harmonious flow between the two; talent that can be taken for granted.
- ☍︎ Opposition: 180°: two drives pulling in opposite directions; awareness through contrast and balance.
What is not here yet
Transits, progressions, synastry between two charts and longer interpretive text are planned. Any future explanation of a chart written by AI will only describe the placements calculated here; it will never supply placements of its own.