What is a birth chart?

A birth chart (also called a natal chart) is a map of where every planet was at the exact moment you were born. It is calculated from three pieces of information: your birth date, birth time, and birth location. Think of it as a snapshot of the sky from the place where you entered the world.

How a birth chart is calculated

To generate a birth chart, we need the positions of the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto at your exact moment of birth. These positions are calculated using an ephemeris — a mathematical model that tracks where celestial bodies are at any given time. We use astronomy-engine, which implements the VSOP87 planetary theory and provides sub-arcsecond accuracy. The birth location determines your local horizon, which is needed to calculate your Rising sign and house placements.

What the planets represent

Each planet in your chart corresponds to a different part of your personality or life experience. The Sun represents your core identity — who you are at your center. The Moon represents your emotional world and how you process feelings. Mercury governs how you think and communicate. Venus describes how you love and what you value. Mars shows how you take action and assert yourself. The outer planets (Jupiter through Pluto) move slowly and describe generational themes and deeper psychological patterns.

Signs, houses, and aspects

Each planet sits in a zodiac sign, which colors how that planet expresses itself. It also sits in a house, which determines the area of life it influences most. Aspects are the geometric angles between planets — they describe how different parts of your personality interact, whether harmoniously or with tension. A complete chart reading considers all of these layers together.

Why birth time matters

Without your birth time, we can still calculate the positions of most planets with reasonable accuracy. But the Rising sign changes roughly every two hours, and the Moon can shift signs within a single day. If you have your exact birth time (often found on your birth certificate), the chart becomes significantly more personal and accurate. Without it, we can still give you a meaningful reading — it just has a wider margin.