What is a Natal Chart (Birth Chart)?

A photograph of the sky at the moment you were born, seen from the place you were born — and the foundation every other chart type in astrology is built on. Synastry, transits and progressions all, in the end, compare something against this single chart.

It takes three pieces of information

Casting a birth chart requires three things: date, time and place. All three are needed, because each one determines something different:

Date — gives the sign the Sun was in, and where the other planets stood that day.
Time — determines the Rising sign (Ascendant) and the house system. Without the time, house positions cannot be calculated reliably.
Place — latitude and longitude decide which houses the planets fall into. Two people born at the same moment in different cities can have different Rising signs.

What's in the chart: planet, sign, house

A birth chart is the intersection of three layers. Every planet sits in a sign and in a house — the three are read together, and none of them means much alone.

Layer	The question it answers
Planet	Which theme, which drive? (Mercury = communication, Venus = value/affection)
Sign	How is that drive expressed? (Aries = direct, Cancer = protective)
House	Which area of life does it show up in? (7th house = relationships, 10th = career)

An example: Mercury in Virgo in the 3rd house means the drive to communicate (Mercury) is expressed in a precise, detail-oriented style (Virgo), in the area of everyday surroundings, siblings and short journeys (3rd house).

Aspects: what the planets say to each other

Planets stand at particular angles to one another in the chart — conjunction (0°), sextile (60°), square (90°), trine (120°), opposition (180°). These are called aspects, and they show how two planetary energies work together: trines and sextiles are considered flowing, squares and oppositions tense — though "tense" here does not mean bad, it means pressure to grow.

The Rising sign matters as much as the Sun Most people know only their "sign" — their Sun sign. But in a birth chart the Rising sign (Ascendant), the sign coming up over the eastern horizon at your moment of birth, shapes how your personality reads from the outside just as strongly as the Sun does. When the two are in different signs, a person tends to know themselves one way while everyone around them sees another.

What it's used for

A natal chart is not a list of conclusions; it is a starting point. Every other technique — transits, progressions, synastry, returns — produces meaning by comparing something against this one chart. Get your birth chart calculated correctly once, and everything else is built on top of it.

Synastry Chart

What surfaces when two birth charts are laid over each other?

Transit Chart

How is today's sky speaking to your birth chart?

ALVEM's Natal Chart screen calculates these three layers (planet / sign / house) along with the aspects, and draws them on a readable wheel.