Personal, social and outer planets
The farther a planet is, the slower it moves through the zodiac and the more people share its sign. This is the main thing to know before reading “a planet in a sign”: your Pluto sign is almost certainly the same as your classmates’, while the Moon sign can differ even between twins if the Moon changed sign between their births.
Time in a sign and the shares of retrograde planets are our measurement from the NASA JPL DE440 ephemeris: signs — over the years 1900–2100, retrogradation — on 20,000 random moments from 1950–2010.
- The Sun and the Moon are the luminaries, Mercury, Venus and Mars are the personal planets: their sign differs for people born weeks apart, and for the Moon — days apart.
- Jupiter and Saturn are social: the sign is shared by peers born within a year or two.
- Uranus, Neptune and Pluto are outer: the sign is shared by a whole generation. What speaks about a person is their house and conjunctions with the Sun, the Moon and the Ascendant.
Retrograde planets
Retrogradation is apparent backward motion: from Earth it looks as if the planet is moving backward through the zodiac. In fact it’s an overtaking effect, like a car in the next lane. That’s why each planet has its own place for retrograde motion: Mercury and Venus go backward only when passing near the Sun, Mars and the distant planets only opposite it. By our measurement for 1950–2030, retrograde Mars was at least 129° away from the Sun, Jupiter at least 114°, Saturn at least 108°, while retrograde Venus was never farther than 29° from it. The Sun and the Moon are never retrograde.
A retrograde planet at birth isn’t rare: by our measurement at least one is found in 89.5% of people, 2.3 on average. That’s why conclusions about character are drawn only from Mercury, Venus and Mars, which go backward less often; for Jupiter and the distant planets retrograde motion happens to a third to half of people and says nothing about a person.
How to read a planet in a chart
The formula is simple: the planet is what’s at work, the sign is how, the house is where, the aspects are what it’s linked with. Mars in Taurus in the 10th house is drive (Mars), stubborn and slow (Taurus), in career (the 10th house). It’s worth starting with the Sun, the Moon and the Ascendant, then Mercury, Venus and Mars. Jupiter and Saturn are read primarily by houses, Uranus, Neptune and Pluto — by houses and by conjunctions with the personal points of the chart.
The manner of each sign is described on the zodiac sign pages, the areas of life — on the house pages. The master of the sign at the start of a house links them together: wherever it stands, that’s where the area of this house is drawn.
What is known without a birth time
The signs of all planets except the Moon are almost always known from the date alone: they don’t manage to change sign within a day unless the birthday fell on a transition. The Moon changes sign within the day on 43.9% of dates (our measurement, 1950–2025) — then without the hour of birth two options remain. The houses of the planets aren’t calculated at all without an exact time: in a day every planet goes through all twelve houses.
What here is astronomy, and what is interpretation
Where a planet stands, whether it’s retrograde and which house it’s in is astronomy: it can be recalculated from any ephemeris. That Mars is about drive and Venus is about taste is interpretation, and it has no evidence base. That’s why the descriptions of planets here are a description of the system, and every statement about a person says when it’s not about you.