Synastry
Synastry is the comparison of two birth charts: how one person's planets fall on the other's chart. It is the full astrological counterpart of "compatibility," as opposed to the simplified comparison by sign.
How It Works
One person's chart is overlaid on the other's, and the aspects between their planets are examined.
What counts as significant:
- The Sun and the Moon: mutual aspects are considered the basis of understanding.
- Venus and Mars: attraction and sexual compatibility.
- Saturn: aspects from one person's Saturn to the other's planets are read as a limitation and, at the same time, as what holds the couple together.
- Houses: which of your partner's houses your planets fall into. The seventh is marriage, the fifth romance, the eighth depth and crises.
The second technique is the composite: a chart built from the midpoints between the two people's planets. It describes not the people but "the relationship as a third entity."
How it differs from sign compatibility
Zodiac Sign Compatibility compares two Sun signs, that is, two out of twenty parameters. Synastry compares the charts as a whole.
The practical consequence: couples with "bad" sign compatibility may well have harmonious synastry, and vice versa. Astrologers say so openly and usually ask people not to draw conclusions from Sun signs.
Synastry and percentages
Full synastry requires the exact time and place of birth of both people: without them, the houses cannot be calculated. Besides, a strong aspect can attract and cause conflict at the same time, so any compatibility percentage depends on how the aspects are weighted.
We have an ideal partner finder by synastry: it compares your planets with the planets of every day in the selected years by aspects, without houses, and ranks the dates on its own scale. The percentage there compares the dates with one another rather than measuring a relationship. For a quick estimate there are zodiac sign compatibility and compatibility by date of birth, both with an honest note that the scale is arbitrary.
An Honest Look at the Method
Studies of astrological compatibility, including one that compared the birth dates of tens of thousands of married couples, find no link between charts and how long marriages last.
That said, synastry can be useful as a prompt to talk about differences. The only danger: a decision to break up or to marry made because of a chart is a decision made about something other than the person.