Introduction
The phenomenon where a planet located near the cusp (the beginning) of the subsequent house is considered as belonging to that house is often termed as "shifting into the next house" or "shift into the next house."
The rationale behind this is that although the planet might technically be positioned within one house, it is so close to the cusp of the following house that it "operates" or "resonates" more with the meanings of that subsequent house.
Principle and Explanation
Theory of Energies
One common explanation is that the house cusps are zones of potent astrological energy. When a planet nears a cusp, it starts to "feel" or be influenced by the energy of that cusp and, by extension, the house it signifies as a cusp. This is similar to how a planet nearing another planet by transit or progression starts feeling the influence of that other planet even before they are exactly conjunct.
Michel Gauquelin's Statistics
Michel Gauquelin, a French psychologist and statistician, conducted statistical studies on planetary positions in birth charts of individuals in various professions.
While he didn't specifically address the "shift into the next house" issue, his findings highlighted that certain planets tended to appear significantly more frequently in specific "sectors" or zones of the birth chart.
These sectors often correspond to areas just before and after the cusps of angular houses (the Ascendant, Midheaven, etc.).
Although his research didn't directly address the "shift into the next house" matter, it underscored the significance of zones close to house cusps.
What's the Correct Distance to Consider?
There's no universal consensus on the exact distance a planet should be from a house's cusp to be regarded as being in the subsequent house. Opinions vary:
Some astrologers, a minority, entirely dismiss the concept of "shifting into the next house" and strictly interpret the planet in the house where it technically resides.
It's worth noting that neglecting this shift is rarely used, often only by beginner astrologers or introductory astrology manuals. Experienced astrologers seldom overlook this interpretative shift.
Others might employ a traditional orb or distance, akin to aspects, of 3, 5, or even up to 8 or 10 degrees for certain points, especially the Ascendant and Midheaven.
Some astrologers indeed apply larger distances for angular houses - Ascendant, Midheaven, and to a lesser extent, Imum Coeli and Descendant, as these houses (and their cusps) are viewed as having a stronger influence.
A common approach is to allow an orb or distance from the next house of 5 degrees for angular houses (1, 4, 7, 10) and a smaller distance, perhaps 1 to 3 degrees, for the other eight houses.
Conclusion and Astrotheme's Decision
As with many astrological topics, the decision to employ (or not) the "shift into the next house" concept and the precise distance to consider will often hinge on personal preferences, experience, and an astrologer's tradition.
On Astrotheme, based on our experience and conscious decision, we employ a method we view as classical and moderate. We believe that more isn't always better. Between neglecting this shift entirely and treating it with significant distances of 5 to 10 degrees, we've settled for a shorter span: two degrees for the Ascendant and Midheaven and one degree for the other ten houses.
This decision stems from analyzing celebrity birth charts and those of our acquaintances over several years, particularly those with planets close to angles and subsequent houses. This "shift" of 1 and 2 degrees seemed appropriate in almost all instances, from our perspective.
To put it simply, any planet within two degrees of the Ascendant and Midheaven - in houses 12 and 9 - belongs to houses 1 and 10, and if it's within one degree of any other house, it already belongs there. In particular, the calculations of dominants in the applications concerned take this into account.
Online free applications for basic charts provide the option, under each sky map and solely out of curiosity, to choose the "no shift into the next house" option. The same applies for the comprehensive portrait, child portrait, and career and vocation reports in the shop.
For double charts (synastry theme, solar return) and other shop reports (compatibility reports, forecasts using the transit method, date agendas), the conventional shift into the next house is applied. This isn't the case for horary astrology, a very distinct branch of astrology.
A note, however: this shift phenomenon becomes significant for interpretation only if you know your birth time, preferably to within a minute or two.
A degree in house position in a birth chart equates to an accuracy of about 4 minutes on birth time. If you aren't certain of your birth time, the uncertainty about planetary positions in houses for these specific borderline cases will be even greater. Comparing reality with interpretation can, in some cases, assist in fine-tuning the birth time.