What houses are
Houses divide the sky not by zodiac signs but by the horizon and meridian of the place of birth. The frame is set by four points: the Ascendant — the degree rising in the east, where the 1st house begins; the Nadir (IC) — the lowest point, the start of the 4th; the Descendant — the degree setting in the west, the start of the 7th; the Midheaven (MC) — the highest point, the start of the 10th. Each of the four quarters is divided into three more parts — that makes twelve houses, and they’re counted from the Ascendant counterclockwise.
Signs and houses are two different circles. Signs are tied to the Sun’s yearly path: it passes through a sign in a month, and everyone born on the same day has the Sun in the same sign. Houses are tied to the Earth’s rotation: in a day every planet goes through all twelve houses. That’s why two people born on the same day in the same city a few hours apart have almost the same planets in signs but different ones in houses.
Why houses need an exact birth time
The sky turns by a degree roughly every four minutes, and the boundaries of all houses shift with it. We measured how sensitive this is: we took 20,000 random moments from 1950–2010 for Moscow and shifted the time. A 10-minute shift moved at least one of the ten planets into a neighboring house in 58% of charts, half an hour — in 94%, an hour — in almost all, 99.8%.
So “around nine in the morning” isn’t a time for the houses: you need a record accurate to the minute, ideally from a document. The city is needed too — the horizon depends on it — but the nearest large city in the same time zone is enough (more in the article on the place of birth). If the time is unknown, the houses in the calculation aren’t yours; what can be calculated without a time and how to narrow it down by the dates of events is covered in the article “I don’t know my birth time”.
Which house system the site uses
The quarters can be divided into three in different ways, and there are dozens of house systems. The site calculates by the Placidus system — the most widespread in modern Western astrology. It’s named after the 17th-century Italian monk and mathematician Placido de Titi and divides not degrees but time: each quarter is three equal stretches of a point’s daily path across the sky. That’s why the houses come out unequal: at the latitude of Moscow the largest house of a chart is usually about 47°, the smallest about 16°; at the latitude of Krasnodar — about 41° and 20° (medians over the same 20,000 charts).
Beyond the Arctic Circle — in Murmansk, Norilsk — Placidus is undefined: some degrees of the zodiac there don’t rise or set at all. For such places the site calculates houses by the Porphyry system: each quarter between the angles is divided into three equal parts by degrees. Which system was used is written in the calculation next to the house table.
There is another tradition too — whole sign houses, one of the oldest: Hellenistic astrologers used it. There the whole sign of the Ascendant counts as the first house, the next sign as the second, and so on. The difference isn’t cosmetic: by our measurement for Moscow, when switching from Placidus to whole signs, on average 6 planets out of 10 change house. If you’re comparing your chart with another program, check the house system first.
How to read a house in your chart
A house has four sources of meaning, and it’s convenient to look at them in order.
- The sign at the start of the house (the cusp). It describes the style in which the affairs of this area go. The start of the 1st house is the Ascendant, of the 10th — the MC.
- Planets in the house. Each adds its own theme: Saturn — work and limits, Jupiter — growth and generosity, Mars — drive and arguments. The closer a planet is to the start of the house, the more noticeable it is.
- The ruler of the house — the master of the sign at its start. Wherever it stands, that’s where the area is drawn: the ruler of the 2nd house in the 10th links money with career.
- An empty house. In a typical chart five to seven houses out of twelve are empty, 5.8 on average by our measurement. There are ten planets for twelve houses, and Mercury and Venus always stay close to the Sun: Mercury no farther than 28°, Venus roughly no farther than 47°. An empty house doesn’t mean an empty area of life: it’s read by the sign at the start and by its ruler.
Because houses are unequal, a sign sometimes ends up entirely inside a house and doesn’t get a single cusp — this is an intercepted sign, or interception. Then the house has two rulers: the master of the sign at the start and the master of the intercepted sign.
In the calculation on the site, each planet has the number of its house, and each house has the sign at its start. You find the ruler of a house yourself: the sign at the start → the sign’s master from the table below → the house where that master stands. For the first house this has already been done: the calculation names the chart ruler.
Rulers of the signs
This is the same table the site calculates with. For Scorpio, Aquarius and Pisces the modern ruler is named first, and in brackets the classical one, as it was before the discovery of Uranus, Neptune and Pluto. The dispute between them in astrology isn’t settled.
Check that the houses are calculated correctly
Before reading the meanings, it’s worth making sure the chart is calculated from your data. There’s a check for this that doesn’t depend on any interpretation — the Sun. If your Sun is in the 7th–12th house, the birth fell in the daytime, when the Sun was above the horizon; if in the 1st–6th — at night.
By Placidus the rule is even more precise. The day is divided into four intervals: from sunrise to true noon, from noon to sunset, from sunset to true midnight and from midnight to sunrise. Each interval is divided into three equal parts, and each part is one house. We checked this on the same 20,000 charts: the Sun’s house matched such a third in all charts except a handful exactly on the boundary.
True noon is the moment when the Sun is highest in the day; it’s exactly halfway between sunrise and sunset and almost never coincides with 12:00 on the clock: in Moscow it’s now around 12:30, and in summer, in the years when daylight saving time was in force, around 13:30. True midnight is twelve hours after noon. In central Russia one such third lasts from an hour (a winter day, a summer night) to three hours (a summer day, a winter night).
How to use it: take the sunrise and sunset times for the day and city of your birth from an astronomical calendar and find your third. If the Sun in the chart is in a different house, the wrong time, time zone or city went into the calculation, and none of the houses in the chart are yours. If the boundary is less than a quarter of an hour away, the check decides nothing: calendars give sunrise by the upper edge of the Sun with a correction for refraction, while houses are calculated by the center of the disc.
What here is astronomy, and what is interpretation
The positions of the planets and the boundaries of the houses are astronomy: they can be recalculated in any program using the same house system, and you’ll get the same degrees. But that the second house is money and the seventh is marriage is interpretation built up over two thousand years. Astrology has no evidence base, so everything said about the meaning of houses in this section is a description of the system, not an established fact.
The page of each house has a “How to check it on yourself” block: the statements there are worded so that they can turn out false about you, and next to them it says what counts as a contradiction. Houses don’t predict events and don’t make diagnoses: the sixth house on the site is about routine and habits, the eighth is about shared resources and crises, not about illness and death.