Astrology glossary

Angle: Any of the four cardinal points of a chart: the Ascendant, Imum Coeli, Descendant and Midheaven. They're derived from the horizon and meridian of the birthplace and, in quadrant house systems, coincide with the cusps of the 1st, 4th, 7th and 10th houses. Planets close to them are considered especially prominent.
Applying aspect: An aspect that hasn't yet become exact: the faster planet is moving toward the precise degree. Traditionally its influence is considered to be building, like something still taking shape. In transits it points to a theme gaining intensity; in a natal chart it's linked to matters that unfold over time.
Ascendant: The zodiac degree rising over the eastern horizon at the exact time and place of birth. It marks the start of the 1st house and is linked to outward temperament, first impressions and the way someone approaches new situations. Because it shifts a degree every few minutes, calculating it requires an accurate birth time.
Aspect: A specific angular relationship between two points in a chart, measured in degrees along the ecliptic. The major aspects are the conjunction, sextile, square, trine and opposition. They describe how two planets' energies interact: whether they merge, support each other or create a tension that calls for adjustment. Aspects are read in natal charts, transits and comparisons between charts.
Composite chart: A single chart that represents a relationship as an entity in its own right. It's built by calculating the midpoint between each pair of planets and points in two natal charts: the midpoint between both Suns, for example, becomes the composite Sun. It doesn't describe either person but the character, purpose and challenges of the bond itself.
Conjunction: The aspect formed when two planets or points sit at practically the same degree, zero degrees apart. Their energies merge and act together, so it's hard to express one without activating the other. Its tone depends on the planets involved: it can feel harmonious, demanding or a bit of both.
Cusp: The line marking the beginning of a house in a chart; the 7th house cusp, for instance, coincides with the Descendant in most systems. In everyday language, people say they were born on the cusp when the Sun was close to changing signs, although technically it always occupies one sign or the other.
Decan: One of the three 10-degree sections each sign is divided into. Its origins go back to the 36 star groups, or decans, of ancient Egypt. Each decan has a sub-ruler that adds nuance to the sign's expression: in the modern approach it follows the signs of the same element, while the older tradition follows the Chaldean order of the planets.
Descendant: The point directly opposite the Ascendant: the zodiac degree setting on the western horizon at birth. It marks the start of the 7th house and relates to how someone forms bonds, the kinds of people they attract or feel complemented by, and what they seek in partners and collaborators. Like the Ascendant, it depends on the exact birth time.
Eclipse: A lunation that takes place near the lunar nodes. In a solar eclipse, during a New Moon, the Moon fully or partly covers the Sun; in a lunar eclipse, during a Full Moon, the Earth's shadow falls across the Moon. They tend to cluster in seasons roughly every six months and are interpreted as amplified lunations.
Element: One of the four groups the signs are sorted into: fire (Aries, Leo, Sagittarius), earth (Taurus, Virgo, Capricorn), air (Gemini, Libra, Aquarius) and water (Cancer, Scorpio, Pisces). Fire is linked to enthusiasm, earth to practicality, air to ideas and water to emotion. How they're distributed in a chart shows its overall balance.
Ephemeris: A table listing the positions of the Sun, Moon and planets at regular intervals, usually daily. For centuries ephemerides were printed as books; today they're computed by software built on high-precision astronomical models. They're the raw material for every astrological calculation, from a natal chart to a horoscope based on the real sky.
Full Moon: The phase when the Sun and Moon are in opposition, in opposite signs, and the Moon's visible face is fully lit. It arrives about fourteen or fifteen days after the New Moon. Symbolically it's linked to culmination, visibility, emotional intensity and letting go of whatever has completed its cycle.
House: One of the twelve divisions of a chart, calculated from the Earth's daily rotation and the local horizon at birth. While signs describe how an energy expresses itself, houses show where in life it plays out: identity, resources, communication, home, relationships and career, among other areas. Because they depend on time and place, two people born on the same day can have very different house placements.
House system: The mathematical method used to divide a chart into twelve houses. There are many: Placidus, Koch, Equal, Whole Sign, Porphyry and Regiomontanus, to name a few. Each calculates house cusps differently, so the same planet can land in different houses depending on the system, especially at latitudes far from the equator.
Imum Coeli: Also known as the IC, this is the point opposite the Midheaven, where the ecliptic crosses the lower meridian beneath the birthplace. In quadrant house systems it marks the start of the 4th house. It relates to roots, home, family of origin and the emotional foundation a person draws strength from.
Ingress: A planet's entry into a new sign, and by extension into a new house. It marks a change in tone: the planet's energy begins expressing itself through the qualities of a different sign. The Sun's ingress into Aries coincides with the March equinox and opens the year in the tropical zodiac.
Luminaries: The traditional name for the Sun and Moon, the two main lights in the sky. Although they aren't planets astronomically, astrology treats them as such and gives them special weight. The Sun is associated with identity and vitality; the Moon with emotional needs, instinct and the way a person seeks security.
Lunar nodes: The two points where the Moon's orbit crosses the ecliptic, the Sun's apparent path. The North Node and South Node are always opposite each other and move backward through the zodiac in a cycle of about 18.6 years. Eclipses happen near them. They're interpreted as the axis between familiar patterns and the direction of growth.
Midheaven: Also called the MC (Medium Coeli), it's where the ecliptic crosses the upper meridian of the birthplace, the highest region of the chart. In most house systems it marks the start of the 10th house. It's associated with vocation, public image, career path and the goals a person pursues in full view of others.
Modality: A sign's mode of action. Cardinal signs (Aries, Cancer, Libra, Capricorn) initiate and coincide with the start of the seasons; fixed signs (Taurus, Leo, Scorpio, Aquarius) sustain and consolidate; mutable signs (Gemini, Virgo, Sagittarius, Pisces) adapt and prepare for change. Together with element, modality defines each sign's basic character.
Moon sign: The sign the Moon occupied at birth. Since the Moon changes sign roughly every two and a half days, knowing it for certain usually requires the birth time. It describes emotional needs, instinctive reactions and what provides comfort and a feeling of home. It often explains nuances that the Sun sign alone can't account for, especially in close relationships.
Natal chart: A map of the sky calculated for the exact moment and place of birth. It shows which sign and house the Sun, Moon and planets occupied, along with the angles they form with one another. Casting one requires the date, time and location of birth. It's the foundation of any personal astrological reading.
New Moon: The phase when the Sun and Moon are in conjunction at the same zodiac degree and the Moon isn't visible from Earth. It marks the start of the lunar cycle, which lasts about 29.5 days. Symbolically it's linked to beginnings, planting seeds and setting intentions in the area of the chart where it falls.
Opposition: The 180-degree aspect, which sets two planets in opposite signs of the zodiac facing each other. It represents a polarity: two needs pulling in contrary directions that ask for balance. It's often experienced through relationships, with part of the tension projected onto other people. Well integrated, it brings perspective and awareness.
Orb: The margin of tolerance allowed around the exact angle of an aspect. For example, two planets 115 degrees apart may count as a trine if a five-degree orb is accepted. The tighter the orb, the stronger the aspect is usually read. There's no universal standard, and the Sun and Moon are often given wider margins.
Personal planets: The fastest-moving bodies in the chart: the Sun, Moon, Mercury, Venus and Mars, although some schools include only the last three. They change signs frequently, so they describe highly individual traits: identity, emotions and how a person thinks, loves and acts. Their transits are brief and set the rhythm of everyday life, from mood shifts to busy weeks.
Placidus: The most widely used house system in modern Western astrology, popularized through tables published by the monk Placidus de Titis in the 17th century. It divides into thirds the time each degree takes to travel from the horizon to the meridian, which produces houses of unequal size. It breaks down at very high latitudes near the polar circles.
Retrograde: The apparent backward motion a planet shows when viewed from Earth. It's an optical effect caused by differing orbital speeds; no planet actually reverses direction. The Sun and Moon never go retrograde. In astrology, retrograde periods are associated with review, reflection and revisiting the themes of the planet involved.
Rising sign: The sign rising over the eastern horizon at the moment of birth, in other words the sign of the Ascendant. It changes on average every two hours, though the length varies with latitude and sign, so it requires an accurate birth time. It's associated with personal style, first impressions and the way someone starts things.
Ruler: The planet associated with a sign, considered its home or domicile: Mars rules Aries, Venus rules Taurus and Libra, Mercury rules Gemini and Virgo, and so on. Modern astrology also assigns Uranus to Aquarius, Neptune to Pisces and Pluto to Scorpio. The ruler of the Ascendant's sign is called the chart ruler and plays a prominent role.
Separating aspect: An aspect that has already been exact, with the faster planet now moving away from the precise degree. It's read as an influence that's fading, something that has happened and is being integrated. In transits it marks the assimilation phase, when what was lived through settles in and becomes experience, and when it's often easier to see the episode clearly.
Sextile: The 60-degree aspect, which usually links signs two apart, typically of compatible elements such as fire and air or earth and water. It's considered harmonious and represents opportunity: it makes cooperation between two energies easier, though it often takes some initiative to make real use of it. Think of it as an open door that still has to be walked through.
Sidereal zodiac: The zodiac anchored to the fixed stars. It's used mainly in Vedic astrology, or Jyotish, and by some Western practitioners. Because of the precession of the equinoxes, it currently sits about 24 degrees apart from the tropical zodiac, so many placements fall in the previous sign. Neither is more correct; they simply start from different reference points.
Social planets: Jupiter and Saturn, which bridge the individual and the collective. Jupiter completes its cycle in about twelve years and Saturn in about twenty-nine and a half, so people born around the same time share their sign placements. They're associated with growth, beliefs, structure, rules and maturity, and their transits often mark important chapters of adult life.
Solar return: A chart cast for the exact moment the Sun returns to the position it held at birth, which happens each year around the birthday, sometimes a day before or after. It's used to explore the themes that may come to the fore during the personal year that's beginning, always as a guide for reflection.
Square: The 90-degree aspect, which usually connects signs of the same modality but different elements. It's read as dynamic tension: two energies with different needs that collide and force a search for solutions. While it can feel like friction, it's also a powerful engine for growth, because it pushes toward action and maturity.
Station: The moment a planet appears to stand still in the sky before changing direction. It can station retrograde, when it begins moving backward, or station direct, when it resumes forward motion. Because it lingers near the same degree for days, its themes are felt more strongly and are often read as turning points.
Stellium: A cluster of three or more planets in the same sign or house; some schools require four. That concentration puts special emphasis on the qualities of the sign or the area of life ruled by the house, which becomes a major axis of the chart. The Sun and Moon usually count toward the group.
Sun sign: The sign the Sun occupied at the moment of birth, and what most people simply call their sign. It depends on the birth date, though for birthdays near a sign change the time matters too, since the dates shift slightly from year to year. It's associated with core identity, vitality and what gives a sense of purpose.
Synastry: The technique of comparing two natal charts by overlaying them. It examines the aspects between one person's planets and the other's, as well as which houses in each chart the other person's planets fall into. It's used to explore the dynamics of a relationship: where it flows easily, where friction appears and what each person stirs in the other.
Transit: The current position of a planet in the sky and the relationship it forms with points in a natal chart, as in Saturn transiting the natal Sun. Fast planets produce brief transits, while slow ones can color several years. Transits are the main tool for reading personal cycles over time, understood as climates for reflection rather than predetermined events.
Transpersonal planets: Uranus, Neptune and Pluto, the outer planets discovered by telescope in 1781, 1846 and 1930. They move very slowly and spend years in each sign, so they describe generational themes and collective processes. In an individual chart they gain personal relevance through the house they occupy and the aspects they make to the personal planets.
Trine: The 120-degree aspect, which usually joins signs of the same element. It's considered the most fluid and harmonious aspect: the energies understand each other effortlessly and support each other naturally. It points to talents and ease. Its only risk is complacency, since what comes easily is sometimes taken for granted and never fully developed.
Tropical zodiac: The zodiac anchored to the seasons rather than to the constellations. Its starting point, 0 degrees Aries, coincides with the March equinox, and each sign spans exactly 30 degrees from there. Because it follows the Earth's relationship with the Sun, the signs keep their link to the seasonal cycle. It's the system used by most Western astrology, including this site.
Whole sign houses: The oldest known house system, already in use in Hellenistic astrology. The entire sign containing the Ascendant becomes the 1st house, the next sign becomes the 2nd, and so on, so each house spans exactly one sign. The same method is used when building horoscopes from a Sun sign.