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The 13 House System: A Necessary System For Real Sky & True Sidereal Astrology

By: Sachi The Scorpio

IG, Twitter, YouTube: @SachiTheScorpio

Once you begin to use the real sky for your astrological calculations, you are bound to notice that the Sun transits through the constellation Ophiuchus during our lifetime. Thus, Ophiuchus is a valid zodiac sign (since a zodiac sign is defined as a constellation that the Sun moves through) leading us to the 13-sign zodiacal wheel. Now it is time to use the only housing system that is appropriate for a 13-sign zodiacal wheel: the 13 House System.

[If you need to brush up on your information about Ophiuchus, you can do so with this article here:]

In this article, we will discuss what the 13-House System is, how it is calculated, and why it is the most appropriate Housing system to use for Real Sky / True Sidereal Astrology. We will examine what each of the Houses represent, and how the additional House changes the mainstream 12-House methodology. Additionally, we will touch up on how to use the "new" house in a chart.

Why 13 Houses?

Since Real/True Sky (and True Sidereal) Astrology has 13 signs, it follows logic to use a housing system to reflect this. Since all signs are attributed to an energy of the House that shares the same element and modality (for example, Aries being Cardinal Fire and the First House being Cardinal fire – thus making the 1st House linked to Aries energy, even if a person’s first house is not technically “ruled” by Aries), Ophiuchus deserves the same respect and space within a chart.

The 13-House system also allows Chiron (Ophiuchus’ ruling body) to be “home” in a House as well as in its home constellation, Ophiuchus. Allowing Chiron to have a home in a constellation and a House is essential for an individual's healing process and Chiron’s journey for the collective.

Since Ophiuchus is the healer, medicine (wo)man, and sharer of immortality, the House “devoted” to Ophiuchus share these common themes. But it is important to note that without a proper House devoted to healing, astrology is incomplete in its template to become our most healed self.

[Also - as a Chart Hacker, I help people become their best selves through the data points in their chart. And by utilizing the 13-House system, this goal becomes much more tangible and step-wise with a space devoted to healing and encompassing the alchemical Ophiuchan arts necessary for self-development.]

How Is The 13-House System Determined?

The 13-House system is just like that of the 12-House system, except the additional house is added between the 8th and 9th House of the traditional 12-House system – just like Ophiuchus is the 9th sign. I’ve made a diagram below for those who are more visual learners.

This pushes back the other Houses so that what was traditionally the 9th House (Mutable Fire House often ascribed to Sagittarian energy) is now the 10th. What was traditionally the 10th House (Cardinal Earth often ascribed to Capricornian energy) is now the 11th. What was traditionally the 11th House (Fixed Air often ascribed to Aquarian energy) is now 12th. And what was traditionally the 12th House (Mutable Water often ascribed to Piscean energy) is now the 13th House.

In a list form, the 13 House System, the energies are as follows:

First House: Cardinal Fire

Second House: Fixed Earth

Third House: Mutable Air

Fourth House: Cardinal Water