The Reference · Words & History
The lexicon.
Astrology has its own vocabulary — four thousand years of it. Below, first the story of where this language came from, then a plain-English glossary of every term you will meet across Astrarium. New to aspects? See them move in the Aspect Explorer \u2192
Plate · The Origins
Four thousand years of looking up.
Astrology began as record-keeping. In Babylon, more than three thousand years ago, temple scribes logged the movements of the Moon and planets alongside events on earth — floods, harvests, the fortunes of kings — searching for patterns. From them we inherited the twelve-fold zodiac band and the idea of the planets as powers with distinct characters.
The system we would recognise was assembled later, in Hellenistic Egypt, where Greek philosophy met Egyptian and Babylonian sky-lore in the melting pot of Alexandria. Between roughly the second century BCE and the second century CE, astrologers there invented the horoscope proper — the chart cast for an individual's exact birth moment, divided into houses, laced with aspects. Ptolemy's Tetrabiblos gathered it into a system that would be copied for a millennium.
When Europe forgot this knowledge, the medieval Islamic world kept and advanced it, translating the Greek texts and refining the mathematics. The debt is written across the sky itself: the star names we still use — Aldebaran, Altair, Betelgeuse, Rigel — are Arabic. Astrology returned to Europe through these translations and flourished through the Renaissance, when it was still inseparable from astronomy.
The two parted in the Enlightenment, as astronomy became a physical science and astrology did not. Yet it never vanished. The twentieth century gave it a new, psychological turn — figures like Alan Leo and, in spirit, Carl Jung reframed the chart as a map of the inner self rather than a forecast of fate — and the newspaper sun-sign column carried it to millions. Astrarium follows that thread: astrology not as prediction, but as a symbolic language for reflection.
Plate · The Glossary
Every term, plainly.
Ascendant
Also the Rising Sign. The zodiac sign climbing over the eastern horizon at the exact moment of birth. It marks the cusp of the first house and describes the manner you meet the world — the mask before the deeper self.
Aspect
The angle between two points in a chart, measured in degrees. Major aspects — conjunction, sextile, square, trine, opposition — describe whether two planetary forces cooperate, tense, or ignore one another.
Conjunction
A major aspect of roughly 0°: two planets sitting together, their energies fused and intensified. Whether that fusion is easy or difficult depends on the planets involved.
Cusp
The boundary line between two signs, or between two houses. A birth near a sign cusp is why an exact time and date matter for placing the Sun with confidence.
Ecliptic
The Sun's apparent path across the sky over a year. The zodiac is the band of sky stretching a few degrees either side of it, through which the Sun, Moon, and planets appear to travel.
Element
One of the four natures a sign belongs to: fire, earth, air, water. The element is the raw material of a sign — what it is fundamentally made of.
Ephemeris
A table of the positions of the Sun, Moon, and planets over time. Every accurately calculated chart rests on one; it is the raw astronomical data behind the symbolism.
Exaltation
A sign in which a planet is traditionally said to express with special strength and grace — as the Sun is exalted in Aries, or the Moon in Taurus.
House
One of twelve divisions of the chart, each governing an arena of life — from the self and money to partnership, career, and the hidden. A planet's house shows where its story unfolds.
Luminary
The Sun or the Moon — the two great lights, treated separately from the planets. Together they are the most important placements in a chart.
Lunation
A new moon or a full moon: the two turning points of the lunar cycle, when Sun and Moon meet or oppose one another across the sky.
Midheaven
Abbreviated MC, from the Latin Medium Coeli. The highest point of the chart, marking the tenth house — career, reputation, and public standing.
Modality
Also Quadruplicity. Whether a sign is cardinal (initiating), fixed (sustaining), or mutable (adapting). The modality describes how a sign moves through time.
Natal Chart
Also the Birth Chart. A map of the sky drawn for the exact time, date, and place of a birth — the foundational document of astrology.
Node
The Lunar Nodes are the two points where the Moon's orbit crosses the ecliptic. In astrology the North and South Nodes form an axis often read as a story of growth and release.
Opposition
A major aspect of roughly 180°: two planets facing each other across the chart, creating polarity and tension that pulls toward balance.
Retrograde
The apparent backward motion of a planet against the stars, an illusion caused by Earth's relative orbital speed. Astrologically, a window to review rather than launch.
Ruler
The planet that governs a sign — Mars rules Aries, Venus rules Taurus, and so on. A sign's ruler colours how it behaves and where its power flows.
Sextile
A major aspect of roughly 60°: an easy, supportive angle offering opportunity and flow, if the person chooses to use it.
Square
A major aspect of roughly 90°: friction, challenge, and productive tension. Squares are uncomfortable and are often where growth is forced.
Synastry
The comparison of two natal charts to study a relationship — laying one sky over another to see where they harmonise and where they grate.
Transit
The position of a planet right now, forming aspects to a natal chart. Transits are astrology's weather: the moving sky acting on the fixed map of a birth.
Trine
A major aspect of roughly 120°: the most harmonious angle, where two planets share an element and cooperate almost effortlessly.
Zodiac
The band of twelve equal signs along the ecliptic, from Aries to Pisces. The word comes from the Greek for 'circle of little animals.'