House overlays
Where a partner's planets land in your chart. Any given house has a 54.3% chance of holding at least one of them — before any meaning is involved.
Arithmetic first
Half of all strangers occupy your eighth house
An eighth-house overlay gets written up as a rare karmic bond. It occurs in 54.3% of random pairings, because twelve houses divided into nine planets leaves almost every house occupied by someone. The expected number of their planets in any one of your houses is 0.75.
That does not make the reading empty — it means the useful detail is which planet and how close to the cusp, not whether the house is filled.
Houses are the most time-sensitive thing in a chart
The ascendant advances one degree every four minutes, and a house spans thirty degrees. So an error in the birth time moves the entire grid:
| Error in birth time | Ascendant shifts | Houses shift |
|---|---|---|
| 15 min | 3.8° | 0.13 houses |
| 30 min | 7.5° | 0.25 houses |
| 60 min | 15° | 0.5 houses |
| 120 min | 30° | 1 house |
| 240 min | 60° | 2 houses |
Two hours out and every planet moves to the next house along — the eighth-house reading you were given becomes the seventh or the ninth. Most people know their birth time to the nearest hour at best, and hospital records round. This is the single strongest reason to treat house overlays as the least reliable layer of a synastry reading, and it is almost never stated.
Aspects between planets do not have this problem — only the Moon and the ascendant move fast enough to matter. Aspects →
89,320 searches a month across all twelve
All twelve, by how often they are asked about
The order is telling: the twelfth and eighth beat the seventh, which is the house tradition assigns to partnership. People ask about the hidden and the heavy, not about the one that is supposed to be the subject.
| House | Covers | Searched |
|---|---|---|
| 12 | what is hidden, dissolved or carried unconsciously | 16,120/mo |
| 8 | shared resources, exposure and what is not said aloud | 15,010/mo |
| 7 | partnership as an arrangement | 13,890/mo |
| 5 | romance, play and creative output | 7,850/mo |
| 1 | first impressions and self-presentation | 7,720/mo |
| 4 | home, family and the private self | 7,510/mo |
| 2 | money, possessions and self-worth | 5,060/mo |
| 10 | public standing and direction of work | 4,200/mo |
| 11 | friendship, groups and shared aims | 3,650/mo |
| 3 | everyday talk and thinking | 3,030/mo |
| 9 | belief, distance and what you consider true | 2,930/mo |
| 6 | routine, work and health | 2,350/mo |