Astrology and numerology glossary: chart, ascendant, aspects, numbers

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The basics of the sky and the zodiac

• Astrology: a symbolic system that links the positions of celestial bodies to traits or events. It has no scientific validation. See history and limits.
• Astronomy: the science that studies celestial bodies, their positions and their movements. Not to be confused with astrology.
• Zodiac: the band of sky centred on the ecliptic, divided into twelve sectors of 30 degrees. The word comes from Greek and refers to animal figures.
• Ecliptic: the apparent path of the Sun across the sky over the year, in reality the plane of the Earth's orbit.
• Sign: each of the twelve sectors of the zodiac (Aries, Taurus, and so on). Signs are not to be confused with constellations. See the guide to the signs.
• Sun sign: the sign in which the Sun was at birth. It is the one used in press horoscopes.
• Constellation: a group of stars grouped together by convention. The Sun passes through thirteen constellations, including Ophiuchus.
• Tropical / sidereal: two ways of anchoring the zodiac: on the spring equinox (tropical, Western usage) or on the fixed stars (sidereal, Indian usage). They are offset by about 24 degrees today.
• Precession of the equinoxes: the slow shift of the Earth's axis, which makes the equinox move back by about 1 degree every 72 years (a cycle of about 25,800 years). Attributed to Hipparchus (2nd century BCE).
• Ephemeris: tables that give the positions of celestial bodies day by day. They are used to calculate a chart.

The birth chart and its vocabulary

• Birth chart (or natal chart, or sky map): a diagram of the positions of celestial bodies at the moment and place of birth. See reading your birth chart.
• Ascendant: the sign rising on the eastern horizon at the moment and place of birth. It is calculated using the exact time. See the ascendant.
• Descendant: the point opposite the ascendant, on the western horizon.
• Midheaven (MC): the highest point of the ecliptic above the horizon, associated in some traditions with public life.
• Imum Coeli (IC): the point opposite the Midheaven, associated with family and roots.
• Houses: twelve sectors of the sky linked to areas of life (identity, possessions, communication, home, and so on). Several systems exist (Placidus, whole signs). See the houses.
• Cusp: the dividing line between two signs or two houses. "Born on the cusp" applies to a day close to the change of sign.
• Decan: a 10-degree division of a sign, three decans per sign.
• Luminaries: the Sun and the Moon, which are not planets in the astronomical sense but are treated together in astrology.
• Planets (in astrology): Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Uranus was discovered in 1781, Neptune in 1846, Pluto in 1930 (reclassified as a "dwarf planet" by the International Astronomical Union in 2006). See the basics of astrology.
• Elements: fire, earth, air, water: four families of three signs. See fire, earth, air, water.
• Modes (or qualities): cardinal, fixed, mutable: three families of four signs linked to the beginning, middle and end of a season. See the modes.
• Aspect: the angle between two celestial bodies on the chart. The main ones: conjunction (0°), sextile (60°), square (90°), trine (120°), opposition (180°). See the aspects.
• Orb: the margin of deviation allowed around an exact angle for an aspect to count.
• Domicile, exile, exaltation, fall: the four "essential dignities" of classical astrology: the sign where a planet is considered at home, the opposite sign, a sign of honour and its opposite.
• Ruler of a sign (governor): the planet associated with a sign. Classical schools use the seven visible planets; modern ones add Uranus, Neptune and Pluto.

Rhythms and comparisons

• Retrograde: said of a planet that seems to move backwards in the sky. This is only an appearance caused by the relative motion of the Earth. Mercury is retrograde about three times a year.
• Transit: the current position of a planet compared with its position on the birth chart. Transits are the basis of so-called forecast horoscopes.
• Progression: a symbolic method that advances the birth chart by one day per year of life.
• Solar return: a chart drawn up for the moment when the Sun returns to its birth position, each year, around the birthday.
• Synastry: the comparison of two charts to study a relationship.
• Lunar nodes: the two points where the Moon's orbit crosses the ecliptic. They move through the zodiac in about 18.6 years and are interpreted symbolically.

Numerology and critical thinking

• Numerology: a practice that assigns symbolic meanings to numbers. See the numerology guide. Modern numerology dates from the late 19th or early 20th century, even though Pythagoras is often cited.
• Life path number: a number calculated from the date of birth, reduced to a single digit from 1 to 9 or to a master number. See the step-by-step calculation.
• Theosophical reduction: adding up the digits of a number until a single digit remains (for example, 1987 gives 1 + 9 + 8 + 7 = 25, then 2 + 5 = 7).
• Master numbers: 11, 22 and 33, which are not reduced in most methods. See for example life path 11.
• Angel number: a sequence of repeated digits (111, 444, 1111 ...) that is interpreted as a sign. It is a popular symbolic reading. See the number 1111.
• Mirror hour: a time with symmetrical or repeated digits (11:11, 12:12). See how to read them.
• Gematria: a Hebrew method that assigns a numerical value to each letter in order to compare words. Not to be confused with modern numerology.
• Barnum (or Forer) effect: the tendency to find a vague and general description very personal. Demonstrated by Bertram Forer in 1949.
• Confirmation bias: the tendency to remember what confirms our beliefs and to forget the rest.

This glossary gives the meaning of words as used by astrologers and numerologists. It does not guarantee the validity of their predictions, which have not been demonstrated.

Frequently asked questions

Also read

The meanings mentioned belong to tradition and symbolism. They are neither promises of results nor medical advice. Back to Full glossary.