What is a birth chart?

A map of the sky at the moment and place you were born. The Sun sign is the one everybody knows; the Moon and the ascendant are the two that make a chart personal.

Why do I need my birth time?

The ascendant is the point rising on the eastern horizon, and it moves through a full zodiac every 24 hours — roughly one sign every two hours. Without a time it cannot be calculated at all.

What if I do not know my birth time?

Sun and Moon can still be worked out. The Moon moves about half a degree an hour, so on most days its sign is unambiguous even without a time.

Birth chart

Your Sun, Moon and rising sign — the three placements that actually make a chart yours, calculated and explained rather than asserted.

Date of birth Time of birth — local time where you were born Place of birth

My birthplace is not listed — enter coordinates

The list covers about 69 500 places down to 5 000 inhabitants. For anywhere smaller, the nearest town is close enough — a few kilometres move the ascendant by well under a minute of arc. Entered by hand, the time is read as UTC.

Latitude Longitude — negative for west

The twelve houses

1 Self and appearance 2 Money and values 3 Communication and siblings 4 Home and roots 5 Creativity and pleasure 6 Work and health 7 Partnership 8 Shared resources and transformation 9 Belief and distance 10 Career and reputation 11 Community and hopes 12 The hidden

The planets

☉ Sun ☽ Moon ☿ Mercury ♀ Venus ♂ Mars ♃ Jupiter ♄ Saturn ♅ Uranus ♆ Neptune ♇ Pluto

Why the big three matter more than the Sun alone

The Sun sign is one twelfth of a chart and the only part most people know. The Moon describes what you need rather than what you are, and the ascendant describes how you arrive in a room. Two people sharing a Sun sign but nothing else often recognise almost nothing of each other in it — which is the usual reason astrology gets dismissed after one horoscope column.