Astrology: complete guide

Astrology is the art of reading the position of celestial bodies at the moment of birth to understand personality, life cycles and relational dynamics. This guide walks you through everything — the natal chart, the 12 zodiac signs, the 10 planets, the 12 houses, aspects and transits — giving you the keys to start reading your own birth chart.

Updated April 26, 2026 · Reading time: 13 minutes · By Les Chamades

What is astrology?

Astrology is the study of correspondences between the positions of celestial bodies and human experience. It has been practised for more than 4,000 years across multiple traditions: Babylonian, Egyptian, Greek, Indian (Jyotish), Chinese, Arabic, and then modern Western.

Contemporary Western astrology (known as psychological or humanistic astrology) does not claim to mechanically predict the future. Instead, it offers a symbolic language for describing inner dynamics, cycles of maturation and the resources unique to each individual.

The natal chart: your map of the sky

The natal chart (or birth chart) is a graphic representation of the sky at the exact moment of your birth, as seen from your birthplace. It takes the form of a circle divided into 12 sectors (the houses), in which the 10 planets are placed according to their position across the 12 zodiac signs.

Three pieces of data are required: date, exact time and place of birth. The time is essential for calculating the ascendant and the houses, which shift approximately every two hours.

The natal chart is fixed — it does not change over the course of your life. What evolves are the transits (current planetary positions) that successively activate different areas of your chart.

The 12 zodiac signs

The 12 signs divide the ecliptic (the Sun's apparent path) into 12 sectors of 30°. Each sign colours the expression of the planets within it. They are organised into 4 elements and 3 modalities:

The 10 planets and their meaning

In Western astrology, 10 "planets" are used — including the Sun, the Moon and Pluto. Each governs a psychological principle and one or two signs:

• Sun ☉ — conscious identity, vitality, the will to exist.
• Moon ☽ — emotions, needs, memory, the relationship with the mother.
• Mercury ☿ — thought, communication, exchanges.
• Venus ♀ — love, attraction, value, pleasure.
• Mars ♂ — action, desire, combativeness, physical energy.
• Jupiter ♃ — expansion, luck, faith, philosophy. Cycle: ~12 years.
• Saturn ♄ — structure, limitation, responsibility, maturity. Cycle: ~29 years.
• Uranus ♅ — awakening, disruption, originality, revolution. Cycle: ~84 years.
• Neptune ♆ — dream, dissolution, the spiritual, the ideal. Cycle: ~165 years.
• Pluto ♇ — radical transformation, death/rebirth, power. Cycle: ~248 years.

The 12 astrological houses

The houses are the 12 sectors of the natal chart corresponding to life domains. They are fixed relative to the birthplace and rotate throughout the day — which is why your birth time matters. House 1 begins at the ascendant.

Aspects: how planets speak to each other

Aspects are the angles formed between planets in the natal chart. They indicate whether two planetary principles harmonise, stimulate or tension each other:

• Conjunction (0°) — fusion of two energies. Intensifying. Can be harmonious or complex depending on the planets involved.
• Sextile (60°) — opportunity, ease, fluid exchange.
• Square (90°) — creative tension, challenge, motivation through friction. Often the most dynamic aspects in a life.
• Trine (120°) — natural harmony, easy flow of energy. A talent often unconscious precisely because it comes so easily.
• Opposition (180°) — polarity to integrate, a dialogue between two poles. Often projected onto relationships.
• Quincunx (150°) — a delicate adjustment between two energies that do not naturally "see" each other.

Transits and planetary cycles

A transit occurs when a planet moving through the current sky forms an aspect with a planet in your natal chart. This is how astrology reads life cycles.

Key cycles to know

• Jupiter return (~12 years) — Jupiter returns to its natal position. A period of expansion, opportunity and renewal of meaning.
• Saturn opposition (~14 years) / Saturn return (~29–30 years) — Saturn returns to its natal position around ages 29–30: a time of reckoning, maturity and reorientation. One of life's most significant transits.
• Uranus square (~21 and ~63) — awakenings, disruptions, a need for freedom.
• Pluto opposition (~37–40) — deep transformation of identity, often through a revelatory crisis.

InnerMap's Astrology module will integrate personalised major cycles: when your Saturn return begins, which transits are active this year, which slow-moving planets are currently passing through your houses.

Sun sign, ascendant, moon sign

The three elements most often mentioned in popular astrology:

• Sun sign — the zodiac sign the Sun occupied at your birth. This is what people commonly ask about ("what's your sign?"). It describes the core of the conscious personality.
• Ascendant (AC) — the sign rising on the eastern horizon at the exact moment of your birth. It changes every ~2 hours. The ascendant describes your social mask, the way you come across to others, and your relationship with your body and immediate environment.
• Moon sign — the sign the Moon occupied at your birth. The Moon changes sign every ~2.5 days. It describes your inner emotional world, affective needs and instinct.

Astrology vs Human Design vs Inner Keys

All three systems use planetary positions calculated at birth — often identical or very close. Their readings diverge radically:

• Astrology — describes psychological tendencies, life cycles and relational dynamics. Strong temporal dimension (transits, progressions). A tool for understanding yourself across time.
• Human Design — offers a daily decision-making mechanics (type, authority, strategy). No cycles. A tool for practical discernment.
• Inner Keys — offers a contemplative path of transformation drawing on the same 64 archetypes as Human Design. No cycles, no decisions — simply a deeper presence to your own frequencies.

None of them conflict: astrology tells you what is happening and when, Human Design tells you how to navigate, Inner Keys tells you what to transform within yourself.

Where to begin?

1. Calculate your natal chart — with your exact birth time if possible.
2. Identify your Sun, Moon and ascendant — these are your three main entry points.
3. Place your planets in the houses — see where each planet's energy expresses itself in your life.
4. Look at the major aspects — squares and oppositions are your creative challenges; trines and sextiles are your natural resources.
5. Check where Saturn is — which cycle is it marking for you right now?

InnerMap will soon calculate your full birth chart offline, using the same Swiss Ephemeris already powering your Human Design and Inner Keys. Send us a message to be notified when the module launches.

Frequently asked questions