The Western mirror

Western astrology reads the sky by season rather than by star. Its zodiac begins at the spring equinox, so 0 degrees Aries is a moment in the year rather than a place among the constellations. That choice is why it is called the tropical zodiac, and why it no longer lines up with the stars it was named after.

This page computes the whole chart: the Sun, Moon and rising sign, every planet with its house and its aspects, and the midheaven. Positions come from the astronomy-engine library and are accurate to about an arcminute, and each aspect is shown with the exact orb it was found at rather than a tidy label.

Rising sign, or ascendant

The zodiac sign coming up over the eastern horizon at the moment you were born. It changes about every two hours, which is why it needs a birth time and a birthplace.

Whole sign houses

The oldest house system: the rising sign becomes the whole of the first house, the next sign the whole of the second, and so on. No degree splitting.

Aspect

A meaningful angle between two planets. A conjunction is roughly zero degrees apart, an opposition roughly 180, a trine 120, a square 90, a sextile 60.

Orb

How far from exact an aspect is. A two degree orb is tight and loud; an eight degree orb is loose and quiet.