Western Astrology Terms, Explained

The Big Three

The three placements people mean when they ask 'what's your sign?'

Sun sign

The zodiac sign the Sun occupied at your birth. Represents core identity, ego, and will — the classic 'sign' most people already know.

Moon sign

The zodiac sign the Moon occupied at your birth. Governs emotional needs, instincts, and inner life.

Rising sign (Ascendant)

The zodiac sign that was rising on the eastern horizon at the moment of birth. Shapes first impressions and outward approach to the world.

Signs, elements & modalities

Zodiac sign

One of twelve 30° segments of the ecliptic (Aries through Pisces), each with its own personality and symbolism.

Element

Signs are grouped into Fire, Earth, Air, and Water — a broad temperament each sign shares with two others.

Modality (quality)

Signs are also grouped as Cardinal (initiators), Fixed (stabilizers), or Mutable (adapters) — describing how a sign moves through change.

Ecliptic

The apparent path the Sun traces across the sky over a year. The zodiac belt is measured along this path.

Planets & luminaries

Luminaries

The Sun and Moon — treated as the two most important 'planets' in a chart, though technically neither is a planet.

Personal planets

Sun, Moon, Mercury, Venus, and Mars — move quickly and shape day-to-day personality.

Social planets

Jupiter and Saturn — move more slowly and describe how you engage with society and structure.

Outer (generational) planets

Uranus, Neptune, and Pluto — move slowly enough that entire generations share the same sign, so they're read more by house and aspect.

Retrograde

The apparent backward motion of a planet from Earth's point of view. In astrology it's read as a time to revisit, review, or turn inward on that planet's themes.

Houses

If signs are the 'how' and planets are the 'what,' houses are the 'where' — the life arena a placement plays out in.

House

One of twelve segments of the chart wheel, anchored to the horizon and meridian at the moment of birth, each governing a different area of life (self, money, home, career, etc.).

House cusp

The dividing line — and starting degree — of a house.

Angular houses

The 1st, 4th, 7th, and 10th houses — considered the most powerful, each anchored to one of the four chart angles.

Whole-sign houses

The oldest house system: the sign containing the Ascendant becomes the entire 1st house, the next sign the 2nd, and so on.

Placidus

The most common modern house system, which divides houses by time rather than by whole signs, producing houses of unequal size.

Angles

Ascendant (AC/ASC)

The zodiac degree rising on the eastern horizon at birth; the cusp of the 1st house. Same as the Rising sign.

Midheaven (MC)

The highest point the ecliptic reaches, due south; the cusp of the 10th house. Associated with career and public reputation.

Descendant (DC)

Directly opposite the Ascendant; the cusp of the 7th house, associated with partnerships.

Imum Coeli (IC)

Directly opposite the Midheaven; the cusp of the 4th house, associated with home and roots.

Aspects

Aspects are the angular relationships between two placements — the 'conversations' planets are having with each other.

Conjunction (0°)

Two placements sit at (or near) the same degree. Their energies blend and amplify one another.

Sextile (60°)

An easy, supportive angle that represents opportunity that usually needs a little effort to use.

Square (90°)

A tense angle that creates friction — often the source of growth, but rarely comfortable.

Trine (120°)

A harmonious angle representing natural, easy talent between the two placements.

Opposition (180°)

Two placements sit directly across the wheel from each other, creating a push-pull that asks to be balanced.

Orb

The allowed margin of error, in degrees, for an aspect to still 'count' — tighter orbs are considered stronger.

Chart-reading terms

Natal chart

A map of the sky at the exact moment and place of birth; the foundation for all other astrology.

Synastry

Comparing two people's natal charts, placement by placement, to understand a relationship's dynamics.

Transit

The current position of a planet in the sky, compared against your natal chart, used to time events and themes.

Stellium

A cluster of three or more planets in the same sign or house — an area of concentrated life force.

Chart ruler

The planet that rules your Rising sign, given special weight as a kind of 'narrator' for the whole chart.