What Houses Are

An easy way to hold it: signs are the sky's own divisions, there all year and the same for everyone; houses only exist when you look out from the moment and place you were born. Picture the two as layers: the outer ring divides the sky, the inner ring divides the view from the ground where you stand.

So two people born the same day at different hours share almost every sign and can share no houses at all. That is why a birthday alone cannot tell two people apart.

Finding the houses on a chart: start at the line marked ASC and count downward, anticlockwise — house one, house two, and on round to house twelve. Each house looks at one area of life: house one is how you come across, house four is home, house seven is partners and the people you work with, house ten is your work and public standing. The sign says how a planet acts; the house says where in life it acts.

What the old texts say: in Book III ch. 2 of the Tetrabiblos, Ptolemy takes the degree on the eastern horizon at the moment of birth as the chart's starting point. William Lilly's Christian Astrology of 1647, in “Of the Twelve Houses,” goes house by house through what each one covers; the first is life, stature and form.

The Earth turns once in about 23.9345 hours (NASA figure), and in that time the twelve signs take turns crossing the eastern horizon, roughly two hours each. Two hours out moves the starting point by a sign, and the whole set of houses shifts with it.

So the twelve houses appear on your chart once you enter a birth time. Until then the house layer stays empty, and the signs your planets are in still show. The more exact the time, the more exact the Ascendant and houses; if a birth certificate or a family memory gives a time, start with that.

What the old texts say: Book III ch. 2 of the Tetrabiblos is entirely about how to fix the rising degree for the moment of birth. The text is plain: the starting point comes from the moment.

This app divides houses with Placidus by default. Very far north or south, Placidus has no answer, so the app switches to whole sign houses and says on screen that it switched and why, so you always know where the houses in front of you came from.

There have always been several ways to divide houses. If another site shows you different houses, it has usually used a different method. Check which one you are reading, and the two can sit side by side.

What the old texts say: in “Of the Twelve Houses,” Lilly goes house by house through what each one covers; the first, for example, is life, stature and form.