Most astrology charts are made of a map of the heavens overlayed upon a circle of 12 houses (see explanation of a Chart Layout). Several methods exist for calculating the line divisions between the houses (house cusps), and not all astrologers use the same method.
It is believed that we exist in time and space. The purpose of the astrological houses is to divide our reality into sections. One method is to divide a day’s time (24 hours and 1 complete revolution of Earth about its axis) into 12 divisions. House systems that focus on this method are called “time-based” systems. Another method is to divide the space inside the Earth’s atmosphere into 12 sections, like sections of an orange.
Over the years, people have proposed many different formulas for calculating the divisions with both of these methods. That is why we have so many different house systems in astrology.
You can find many summaries of the house systems on the web, so I will only list the most popular and add a few notes below.
List of House Systems
- The Placidus house system is probably the most widely-used in the United States and Europe. However, here at Astrology Library, we consider the Placidus house system our second favorite, not our first choice. The Placidus house system divides time rather than space.
- The Koch house system is probably the second most popular in the United States. It’s a relatively new system, from the 1970’s. It doesn’t work at all near the poles of Earth, but it’s still very popular.
- The Campanus house system is our favorite at Astrology Library. We find that it works best for psychological readings, as opposed to mundane, electional or horary readings. The Campanus house system divides space instead of time. We are not alone in our support of the Campanus house system: Dane Rudyhar also preferred it. In his book, The Astrological Houses, Dane Rudyhar says:
“…what is essential is the spatial character of the
houses – which fits the Campanus system of house division – and not the time
factor, that is, the time it takes for a zodiacal degree and for the planets to rise
from the horizon to the meridian – Placidus system. Therefore it seems to me
logical to divide the space surrounding the newborn at the surface of the globe
into equal sections. Each house represents 30 degrees of person-centered space
and the Point of Self moves through that space at an even speed from house cusp
to house cusp…”
- Equal Houses
- The Equal House system was the earliest system used. The ascendant makes the first house cusp, then each successive house cusp is exactly 30 degrees after the previous one. The advantage of this house system is that it works well from any point on Earth since the houses are always 30 degrees. The houses do not grow or shrink in size near the poles, as in other house systems. A most annoying issue with this house system is that the M.C. is not the same as the 10th house cusp. In his book, The Astrological Houses, Dane Rudyhar says that any type of equal house system is incomplete because it “does not take into consideration the two axes determined by the time and place of birth.” Equal house systems, including Whole House systems, ignore the vertical axis and use only the horizon. (The Whole House system is like the Equal House system, with the only difference being that zero degrees of the ascending sign makes the first house cusp. Each successive house cusp is zero degrees of the next sign.)