The asteroid of the terms
Juno is asteroid number three, discovered in 1804 and named for the Roman goddess of marriage. Astrologers read it for the conditions a person needs a long partnership to meet.
That is a narrower question than compatibility. Venus describes what attracts you; Juno describes what you require in order to stay, which is not the same list and frequently not the same person.
Why it needs a separate ephemeris
Asteroid positions are not in the standard planetary theories that browser-based tools use. They need a dedicated ephemeris, which is why most free calculators omit Juno along with Ceres, Pallas and Vesta.
This site samples all four from the Swiss Ephemeris across two centuries and interpolates between the samples. The worst disagreement in the most recent check was under three arc seconds.
What the placement describes
The sign describes the terms. Juno in Capricorn wants a partnership with a visible structure and a shared long horizon; Juno in Aquarius needs room and an arrangement negotiated rather than assumed.
The house describes where those terms have to be met. Juno in the sixth wants a partner who shares the daily routine; in the ninth, one who shares a worldview. That is the more specific half and it needs a birth time.
Juno in synastry
This is where the asteroid earns its keep. Contacts between one person's Juno and another's Sun, Moon, Venus or ascendant are read as the terms being met or refused.
The marriage calculator pulls those contacts out alongside Saturn links, since durability is what both bodies describe. Juno alone in a natal chart is a description of your requirements; Juno in comparison is a description of whether they are being offered.
How long it stays in a sign
Juno orbits in about four years and three months, so it spends roughly four months in a sign. That puts it between the personal planets and the generational ones.
The orbit is eccentric, so the pace varies: some signs take two months and others eight. The calculator gives the exact window your Juno held rather than assuming an average.
The other three asteroids
| Asteroid | Read for |
|---|---|
| Ceres | How you nurture and how you want to be looked after |
| Pallas | Pattern recognition and strategy |
| Juno | The terms of a committed partnership |
| Vesta | What you protect and stay devoted to |
The four are usually read together as a set, and each has its own calculator here. They are minor bodies and should be weighted accordingly: an asteroid placement rarely reorganises a reading and frequently sharpens one.
How much weight to give it
Less than the planets. A Juno with no close aspect to a personal planet or an angle is quiet, and quiet Junos are common.
The interpretation is also modern. Juno was discovered in 1804 and the marriage reading was developed largely in the twentieth century, so it has considerably less tradition behind it than anything in the classical set.
Common questions
What is Juno read for?
The conditions a person needs a long partnership to meet. Venus describes what attracts you; Juno describes what you require in order to stay.
Why do most free calculators omit it?
Asteroid positions are not in the standard planetary theories browsers use. They need a dedicated ephemeris, which this site samples from the Swiss Ephemeris.
How is Juno used in synastry?
That is where it earns its keep. Contacts between one person's Juno and another's Sun, Moon, Venus or ascendant are read as the terms being met or refused.
How long does Juno stay in a sign?
About four months on average, but the orbit is eccentric so some signs take two and others eight. The calculator gives your exact window.
How much weight should I give it?
Less than the planets. A Juno with no close aspect to a personal planet or an angle is quiet, and the marriage interpretation is largely twentieth-century.
Do I need a birth time?
For the sign, no. For the house, which is the more specific half, yes.