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 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 mundande or electional. We are not alone in our support of the Campanus house system: Dane Rudyhar also preferred it.
- Equal Houses
- The Equal House system was the earliest system used. The ascendant makes the 1st 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.