Your chart
Birth chart
A map of where the Sun, Moon and planets were, seen from the place and moment of your birth.
It is also called a natal chart. It shows the sign and house of each planet, and the angles between them. Your birth date gives the signs of the slow planets. Your birth time and place give the Moon’s exact position, your rising sign and your houses. All other parts of astrology are compared with this chart.
Find your Sun, Moon and rising →Big three
Your Sun, Moon and rising signs: who you are, what you feel and how others first see you.
The Sun is your basic character. The Moon is what you need to feel safe. The rising sign is how you meet other people. Most people recognise themselves much better in all three than in their Sun sign alone.
Calculate your birth chart →Rising sign (Ascendant)
The sign that was rising on the eastern horizon at the moment of your birth.
It changes about every two hours, so you need your birth time to know it. It describes your outward style, your body and how you start things. It also decides where each house begins in your chart.
The ten planets
In astrology, the Sun and Moon are also called planets. Each planet stands for a part of life. Its sign shows how it acts. Its house shows where.
- Sun Identity, vitality, purpose. At home in Leo, exalted in Aries.
- Moon Feelings, needs, home. At home in Cancer, exalted in Taurus.
- Mercury Thinking, talking, deals, travel. At home in Gemini and Virgo, exalted in Virgo.
- Venus Love, pleasure, money, beauty. At home in Taurus and Libra, exalted in Pisces.
- Mars Drive, courage, conflict, sex. At home in Aries and Scorpio, exalted in Capricorn.
- Jupiter Growth, luck, belief, generosity. At home in Sagittarius and Pisces, exalted in Cancer.
- Saturn Structure, time, limits, mastery. At home in Capricorn and Aquarius, exalted in Libra.
- Uranus Change, freedom, surprise. At home in Aquarius.
- Neptune Dreams, imagination, dissolving. At home in Pisces.
- Pluto Power, depth, transformation. At home in Scorpio.
The twelve signs
The zodiac has twelve parts of 30° each, starting at the March equinox. Each sign has its own page.
Elements and modes
Four elements
- Fire
- Action and enthusiasm. Fire signs (Aries, Leo, Sagittarius) are enthusiastic and brave, and they start things quickly.
- Earth
- The body and results. Earth signs (Taurus, Virgo, Capricorn) are practical and patient, and they deal well with real things.
- Air
- The mind and people. Air signs (Gemini, Libra, Aquarius) think, talk and bring people together.
- Water
- Feelings and intuition. Water signs (Cancer, Scorpio, Pisces) notice what others feel and care deeply.
Three modes
- Cardinal
- Starters. Cardinal signs (Aries, Cancer, Libra, Capricorn) begin each season and like to start things.
- Fixed
- Keepers. Fixed signs (Taurus, Leo, Scorpio, Aquarius) are in the middle of each season and keep things stable.
- Mutable
- Adapters. Mutable signs (Gemini, Virgo, Sagittarius, Pisces) end each season and adapt easily to change.
The twelve houses
The houses divide your chart into twelve areas of life, counted from your rising sign. A planet’s house shows the area of life where it acts. The Prism app uses Placidus houses. Read about each house.
- 01 Self Your body, your appearance, how others see you and how you start things. It begins at your rising sign.
- 02 Money & values What you earn, own and value. It also covers how much you value yourself.
- 03 Words & neighbourhood Talking, writing, learning, brothers and sisters, short trips and your local area.
- 04 Home & family Your family, where you live, where you come from and your private life at home.
- 05 Pleasure & creativity Romance, fun, children, games and anything you make because you enjoy it.
- 06 Work & health Daily routines, your everyday job (not your career), habits, health and helping others.
- 07 Partners Marriage, close partnerships and contracts. It covers the people you deal with one to one, including open opponents.
- 08 Shared things Intimacy, other people’s money, debts, inheritance, crises and deep change.
- 09 Horizons Long journeys, university, beliefs, publishing, the law and big questions about life.
- 10 Career & reputation Your public role, your ambitions and what people know you for. It begins at the Midheaven, the top point of the chart.
- 11 Friends & hopes Friends, groups, networks, communities and the future you are working for.
- 12 The hidden Rest, time alone, the unconscious mind, endings and things that happen out of sight.
The five aspects
An aspect is an angle between two planets. It shows whether they work well together or not. These five are the classical aspects, first listed by Ptolemy.
- Conjunction 0° Two planets in the same place. They act together, and their themes mix, for better or worse.
- Sextile 60° A helpful angle of 60°. Things work out if you take the first step.
- Square 90° A tense angle of 90°. It is uncomfortable and asks you to act. It often leads to progress.
- Trine 120° An easy angle of 120°. Things work without effort, so easily that you may not use the chance.
- Opposition 180° Two planets on opposite sides, 180° apart. Two needs pull against each other. The answer is balance, not winning.
Timing
Transits
Where the planets are now, compared with where they were in your birth chart.
When today’s Mars makes a square to your birth Sun, that is a transit. Fast planets (the Moon, Mercury, Venus, the Sun and Mars) affect a day or a week. Slow planets (Jupiter to Pluto) affect a year or more. Prism reads transits each morning to give your day its colour.
How Prism reads transits →Retrograde
When a planet seems to move backwards through the zodiac, seen from Earth.
The planet does not really move backwards. It only looks that way because Earth passes it, or it passes Earth. In tradition, the planet’s themes then turn back: you revise, repeat and meet delays. Mercury is retrograde three or four times a year, for about three weeks each time.
Retrograde dates →Moon phases
The Moon’s monthly cycle of light, from new to full and back, every 29.5 days.
In tradition, the waxing half (from new to full) is for starting and growing things. The waning half (from full to new) is for finishing things, letting go and rest. The new Moon is a quiet start. At the full Moon, things reach their high point and people notice them.
Moon phase calendar →Void-of-course Moon
The time between the Moon’s last major aspect in a sign and its move into the next sign.
It happens every two or three days. It lasts from a few minutes to about a day. Tradition says that things started at this time do not lead anywhere. So it is a bad time for launches and signing documents. It is fine for rest, routine and finishing work.
Find days without it →Eclipses
New or full Moons near the nodes, when the Sun, Moon and Earth are in a line.
Solar eclipses happen at new Moons, and lunar eclipses at full Moons. They come in groups about every six months. Astrologers see the weeks around them as times of sudden change. Things start or end quickly. So people often plan big events away from eclipses.
Eclipse dates →Ingress
The moment a planet enters a new sign.
When the Sun enters a sign, that sign’s season starts. For example, the Sun enters Aries at the March equinox. When a slow planet changes sign, the change affects several years.
Today’s sky →Technical terms
Orb
How far from exact an aspect can be and still count.
A square is 90°. But planets 87° apart still make a square, with a 3° orb. The smaller the orb, the stronger the aspect. Prism allows wider orbs for the Sun and Moon. It gives every aspect a weight based on how close to exact it is.
Dignity
How well a planet works in a sign: at home, exalted, in detriment or in fall.
Venus is at home in Taurus and Libra. It works less well in Scorpio and Aries. A planet in dignity does its job easily. A planet in detriment has to work harder for the same result. Electional astrology, which chooses a good moment for an action, uses dignity a lot.
Electional astrology
Using the sky to choose a good moment to start something.
This is the oldest practical use of astrology: choosing the day to marry, sign, travel or launch. It looks at the planet linked to the action, for example Mercury for contracts and Venus for love. It also looks at the Moon’s phase, and it avoids retrogrades and eclipses. Prism’s Plan does this with your own chart.
Best days for anything →Synastry
Comparing two birth charts to see how two people get on.
Synastry does not only compare Sun signs. It looks at the angles between one person’s planets and the other’s, for example your Venus and their Mars. It is the complete version of compatibility.
Sun-sign compatibility →