D

Dark (degrees)

Certain degrees traditionally believed to cause a dark complexion when on the ascendant. Dark degrees are also believed to accentuate deformity, should this be present. See Light and Smoky degrees.

Dark Energy

Dark energy is a mystery. According to NASA, "roughly 70% of the universe is made of dark energy. Dark matter makes up about 25%. Everything on Earth, everything that we have ever observed with all of our instruments – normal matter – adds up to less than 5% of the universe". In cosmology, dark energy is a hypothetical form of energy that permeates all of space and has strong negative pressure, counteracting gravity. Currently explaining the observations of an accelerating universe as well as accounting for a significant portion of the missing mass in the universe. Could this be the æther, the alchemical quintessence, by another name...?

Dark Matter

Invisible matter particles in space that cannot be detected by their emitted radiation but, according to the latest cosmological theories, whose presence can be inferred from gravitational effects on visible matter such as stars and galaxies. Dark matter is believed to account for as much as 30% of the matter in a typical galaxy and may also occupy intergalactic space. Dark Matter in itself has no astrological significance. See Dark Energy, q.v.

Dasa (Dasha)

A major planetary period delineated in Vedic astrology. Compare Alfridaria.

Davison Relationship Horoscope

Horoscope created for the exact midpoint between two birth dates, times and places for the purposes of Relationship Analysis. Devised by Ronald C. Davison, 20th Century English astrologer, this technique is not found in traditional astrology. Compare Composite Chart.

Day-Stars

Jupiter, Saturn, Sun. Mercury is convertible, and may be either Diurnal or Nocturnal. Moon, Mars and Venus are the Night Stars.

Debility

A weakened planetary condition, due to unsympathetic aspect, motion, or position. See Dignity.

Decade

Decan.

Decan (Decanate)

A one-third (ten-degree) sector of a sign. Each sign has three decanates: 0-10 degrees, 11-20 degrees and 21-30 degrees. Each decan has its own ruler, based on the rulership of the first, fifth and ninth sign of its triplicity, counting the current sign as the first. For example, the first decan of Aries is ruled by Mars, the second by the Sun and the third by Jupiter. According to Alan Leo, each decan is also divided into two faces, a positive and a negative, each with its own ruler. Ptolemy has a different decan rulership system, see Ptolemy's Table. Decanates themselves are also known as faces. Decans originally derive from ancient Egytian astrology, where the decans were considered paramount, before being subsumed in Hellenistic times under the Chaldean 12-sign zodiac.

Decile

Minor aspect of 36°. Considered fortunate, also known as semi-quintile.

Declination

Distance of a planet north or south of the celestial equator. Every part of the ecliptic has declination except the beginnings of Aries and Libra (0°00'), because the plane of the ecliptic is not parallel with that of the celestial equator, which meet at those two points. The Sun has maximum declination of 23°28', when it reaches the tropics of Cancer in the north (23°N28') and Capricorn in the south (23°S28'). Declination is due to the inclination of the earth in orbit. See Parallel.

Decreasing in Light

When a planet has passed the opposition to the Sun it is said to be decreasing in light and is correspondingly weaker. This especially applies to the Moon.

Decumbiture

A chart drawn for the time the patient falls ill, for the purpose of diagnosing illness. Alternatively drawn for the time the practitioner is first contacted by the patient.

Deferent

Planetary sphere. In order to maintain aristotelian circular motion of planets while explaining the retrograde motion of planets in the ancient geocentric Ptolemaic system, epicycles were introduced. The planets were said to revolve in a circular motion around a point attached to the appropriate planetary sphere (or deferent), while moving at a uniform angular velocity. This idea is now obsolete, due to the acceptance of the modern Copernican system of heliocentric motion.

Degree

The zodiac is divided into 360 equal degrees, marked out into into twelve signs of thirty degrees each. One degree contains 60 minutes and each minute contains 60 seconds of longitudinal arc (in Indian Jyotish astrology even smaller subdivisions are employed). Degrees themselves have meanings, distinguished from the meaning of the sign and decan under which they are subsumed.

Delineation

Interpretation of the horoscope.

Delta T (ΔT)

Drift in apparent clock-time, caused by fluctuations in the Earth's orbit. Primarily due to tidal frictions from the Moon, it is a matter of seconds, but is important for accurate horoscope construction, timing of eclipses and so on. Computer programs for calculating horoscopes should have built-in accounting for this. More on Delta T (off site).

Descendant

The seventh house (or its cusp), governing marriage, partnership and open confrontation.

Descending

Planets appear to be descending when located between the tenth house cusp via the descendant and that of the fourth, when they begin to ascend. Descending planets are considered weaker than ascending ones.

Descending Node

South Node. See Nodes.

Detriment

A planet is weaker and in its detriment when it is in the sign opposing that which it rules. For example, Mars is in detriment when placed in Libra, the opposite of Aries, or Taurus, the opposite of Scorpio.

Dexter

An aspect read to the right by diurnal movement, i.e. clockwise, against the zodiacal motion, which is anticlockwise. It is thus contrary to the natural succession of the Signs. Considered more powerful because more direct and in the line of sight. See Sinister.

Diametral (Diameter)

Opposition.

Differentia

Types of charts used by ancient and mediæval astrologers to determine length of life.

Dignity, Accidental and Essential

A planet is stronger when placed in certain sectors of the chart, which are called its dignities.

• Accidental Dignity
  A planet's position by house (angular, succedent, or cadent), or by other beneficial factors such as well-aspected, increasing in light, elevated, swift, etc.
• Essential Dignity
  A planet's position by sign (home sign, exaltation, or triplicity). See Ptolemy's Table of Essential Dignities and Debilities.

Accidental is more significant than Essential Dignity in the interpretation, although both are important. The unfortunate influence of a malefic is usually diminished when in dignity, whilst the fortunate influence of a benefic is increased.

To calculate the relative strengths of planets in a chart, see Table of Planetary Values.

Direct Motion

Planetary motion through the zodiac in the normal order of the signs. The opposite of Retrograde Motion.

Direction

Direct Motion.

Directions

Aspects between planets in a progressed horoscope; also their aspects to the planets in the natal chart. See Primary Directions.

Disjunct Signs

According to Ptolemy: "Disjunct" and "Alien" are the names applied to those divisions of the zodiac ... which belong neither to the class of commanding or obeying, beholding or of equal power, and [are not in] opposition, trine, quartile, and sextile, and are either one or five signs apart; for those which are one sign apart are as it were averted from one another and, though they are two, bound the angle of one, and those that are five signs apart divide the whole circle into unequal parts. while the other aspects make an equal division of the perimeter.". See Aversion.

Disposition

See Dispositor.

Dispositor

When a planet is in the sign ruled by another, that planet is said to be disposed of by the ruler, its dispositor. For example, Mars in Sagittarius in said to be disposed of by Jupiter, the ruler of that sign. Jupiter is thus the dispositor of Mars. Disposition by a benefic is favourable and especially so if the dispositor is elevated or more elevated than the disposed. Mutual Disposition (when planets are in each other's signs, eg: Moon in Leo and Sun in Cancer) is very favourable and reduces any surrounding negativity. Disposition is particularly important in Horary readings.

Dissociate Aspect

Aspect within orb, but not within the bounds of the aspecting sign. See Out-of-Sign.

Diurnal

During the day, marking planets above the horizon (between the first and seventh cusps via the Mid-Heaven), versus Nocturnal: below the horizon (during the night).

Diurnal Arc

The time in right ascension that a planet or degree of the zodiac takes to move from its rising point to its setting point.

Diurnal Chart

Nativity of person born in the daytime, i.e. when the Sun is above the horizon.

Diurnal Signs

Signs in the southern hemisphere of the chart (above the horizon), namely, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces.

Divination

Fortune telling.

Divine

1. To do with the divinity (or God).
2. To find a solution, either using intuition; tools such as divining rods or pendulum; or symbolic systems such as astrology, tarot, runes etc.

Divine Year

One Divine Year is said to equal 360 solar years.

Divinity

God.

Divisional Chart

A vital part of the Hindu Vedic system, where additional charts (the 16 varga charts) are erected. Based on fractions ("divisions") of each sign, each varga gives light on a different side of the character. This ancient system strongly influenced John Addey, who went on to devise the Harmonic Chart system for Western astrology in the 20th Century.

Dodecatmoria

Ancient Greek 2½ degree division of a sign (one twelfth of 30 degrees). See Duad and Dwadishamsha.

Domal Dignity

A planet in its own sign.

Domicile

The home sign, or throne, of a planet..

Double-bodied Signs

Gemini is known as one of the double-bodied signs (dual signs) because it has two "bodies" in its symbol, the symbol of the Twins. The other dual signs are Sagittarius (part man, part beast) and Pisces (two fishes). They denote dual experiences, twins etc., when on the cusp of fifth or eleventh houses and especially on the ascendant or when populated by many planets. Dual or double-bodied signs often love variety and are drawn to be involved with two people at a time, or have two or more things happening at once, such as two jobs etc. See also Bi-corporal Signs.

Draco

The constellation of the Dragon, which circles the North Pole and never sets. The hundred-eyed dragon, Ladon, twined around an apple tree in the Garden of the Hesperides, guarding the golden apples. He was slain by Heracles in his Eleventh Labour and later placed in the heavens by Hera. In an earlier myth, Draco guarded the Golden Fleece and was slain by Jason, leader of the Argonauts. The Golden Fleece itself originally belonged to the ram, Aries.

Draconic Chart

The natal Dragon's Head (ascending node) becomes 0-degrees Aries of the Draconic chart, or 'draconic equinox' and other planets and points are adjusted accordingly.

Dragon's Head

Caput Draconis, or Moon's North Node. The sign and degree occupied by the Moon when crossing the ecliptic from south to north lattitude. It is usually considered somewhat benefic, and is the opposite of the Dragon's Tail (Cauda Draconis), the South Node, which is considered malefic. In Indian astrology, the Dragon's Head is called Rahu and the Dragon's Tail is called Ketu and both are considered malefic, though less so for Ketu. These significant points traditionally have the strength of a planet and are especially important in directions and transits. More on Dragon's Head & Tail.

Dragon's Tail

Cauda Draconis, or Moon's South Node. See Dragon's Head.

Drekkana

Vedic (Jyotish) term for Decanate.

Duad (Dwad)

2½ degree sector of the zodiac, making one twelfth of a sign. There are thus twelve duads per zodiacal sign, each one governed by each sign in order and so repeating throughout the year. This in duration is approximately equivalent to two and a half days, about the time it takes for the transiting Moon to pass through one zodiacal sign. So the Moon passes through each sign in a month, just as the Sun passes through each sign in a year. See dwadishamsha.

Dual Signs

Gemini; Sagittarius; Pisces. See Double-bodied Signs.

Dwadishamsha (Dwadasamsa)

Division in Indian Astrology of the zodiac into segments of two and a half degrees (i.e. one twelfth of a Sign). Popularised in the modern era in the West by Alan Leo, this division was also used by the ancient Greeks, known as the dodecatmoria. See Duad.

Dwarf Planet

Contentious 2006 astronomical definition of small planetary bodies within the Solar System, including Pluto, Ceres and the newly discovered Eris. It has no astrological significance. See Wikipedia on the subject.