Astrological aspect
In astrology, an aspect is an angle that planets make to each other in the horoscope; as well as to the Ascendant, Midheaven, Descendant, Lower Midheaven, and other points of astrological interest. As viewed from Earth, aspects are measured by the angular distance in degrees and minutes of ecliptic longitude between two points. According to astrological tradition, they indicate the timing of transitions and developmental changes in the lives of people and affairs relative to the Earth.
For example, if an astrologer creates a Horoscope that shows the apparent positions of the celestial bodies at the time of a person's birth, and the angular distance between Mars and Venus is 92° ecliptic longitude, the chart is said to have the aspect "Venus [|Square] Mars" with an orb of 2°. The more exact an aspect, the stronger or more dominant it is said to be in shaping character or manifesting change.
With Natal charts, other signs may take precedence over a Sun sign. For example, an Aries may have several other planets in Cancer or Pisces. Therefore, the two latter signs may be more influential.
History and approach
In medieval astrology, certain aspects and planets were considered to be either favorable or unfavorable. Modern usage places less emphasis on these fatalistic distinctions. The more modern approach to astrological aspects is exemplified by research on astrological harmonics. In 1619, Johannes Kepler advocates this in his book Harmonice Mundi. Thereafter, John Addey was a major proponent. However, even in modern times, aspects are considered to be either easy or hard. Depending on the involved planets, a Conjunction may be in either category.Easy aspects may be positive, because they enhance opportunity for talent to grow.
Hard aspects may be negative, because they enhance a challenge where an adjustment must be made to reach balance. Typically, manifestation may occur with a Conjunction, Square or Opposition.
Planets may be considered. Mars and Uranus tend to ignite while Saturn and Neptune inhibit. Whether a planet is direct or retrograde is of great significance. An eclipse of the Sun or Moon is even more significant. The South Node of the Moon denotes innate wisdom from past experience while the North Node denotes karma and evolution.
Astrological Signs may be considered. For example, the fire signs of Aries, Leo and Sagittarius are more compatible with the air signs of Gemini, Libra and Aquarius. The Earth signs of Taurus, Virgo and Capricorn are more compatible with the water signs of Cancer, Scorpio and Pisces. The mutable signs of Gemini, Virgo, Sagittarius and Pisces may be flexible. The cardinal signs of Aries, Cancer, Libra and Capricorn may change their mind. The fixed signs of Taurus, Leo, Scorpio and Aquarius may be difficult.
Astrological Houses may be considered.
Ptolemaic Aspects
Since they were defined and used by Ptolemy in the 1st Century AD, the traditional major aspects are sometimes called Ptolemaic Aspects. These aspects are the Conjunction, Sextile, Square, Trine, and Opposition. Major aspects are those that are divisible by 10 and evenly divided in relation to 360°.When calculating or using aspects, it is important to note that different astrologers and separate astrological systems/traditions utilize differing orbs, which is the degree of separation between exactitude. Orbs may also be subject to variation, depending on the need for detail and personal preferences. Although, when compared to other aspects, almost all astrologers use a larger orb for a Conjunction.
Kepler's Aspects
Collective astrological data along with Johannes Kepler described 13 aspects in his book Harmonice Mundi. Astrological data grouped together in five degrees of influentially picked from symbol ratios encountered in geometry and music: 0/2, 1/2, 1/5, 2/6, 1/3, 1/12 along with 1/5, 2/5, 15/5, 10, 10/3, 8, and 8/3. The general names for whole divisors are n-ile for whole fractions 1/n, and m-''n-ile for fraction m''/n. A Semi-n-tile is a 2n-tile, 1/, and Sesqui-n-tile is a Tri-2n-tile, 3/.All aspects can be seen as small whole number harmonics,. Multiples of m/''n create new aspects where there are no common factors between n'' and m, gcd=1.
Major aspects
Conjunction
A Conjunction is an angle of approximately 0–10°. Typically, an orb of ~10° is considered to be a Conjunction. If neither the Sun or Moon are involved, some astrologers consider a maximum orb of 8°.Conjunctions are a major aspect in a horoscope chart. They are said to be the most powerful aspects, because they mutually intensify the effects of the involved planets.
Depending on the involved planets, a Conjunction may be beneficial or detrimental. Highly favourable Conjunctions may involve the Sun, Venus, and/or Jupiter as well as any of the three possible combinations. Highly unfavourable Conjunctions may involve the Moon, Mars, and/or Saturn as well as any of the three possible combinations.
Exceptionally, on November 9–10 of 1970, the Sun, Venus, and Jupiter were in a three-way beneficial Conjunction. In that same year, on March 10, the Moon, Mars, and Saturn were in 3-way detrimental Conjunction.
If either of two planets involved in a Conjunction is also under tension from one or more hard aspects with one or more other planets, then the added presence of a Conjunction will further intensify the tension of that hard aspect.
If a planet is in very close Conjunction to the Sun, the Conjunction is of great strength. The planet is said to be Cazimi, which is an ancient astrological term meaning "in the heart". For example, "Venus Cazimi" means Venus is in Conjunction with the Sun with an orb of less than ~0.28°.
If a planet is moderately close to the Sun, the specific orb limit may depend on the particular planet. It is said to be Combust.
Every month of the year, during the New Moon, the Sun and Moon experience a Conjunction.
Great Conjunctions
In the past, Great Conjunctions between the two slowest classical planets, Jupiter and Saturn, have attracted considerable attention as celestial omens. This interest can be traced back to Arabic translations found in Europe; most notably Albumasar's book on Conjunctions. During the late Middle Ages and the Renaissance, these omens were a topic broached by most astronomers. This included scholastic thinkers, such as Roger Bacon and Pierre D'Ailly. Omens are also mentioned in popular literary writings by authors, such as Dante and Shakespeare. This interest continued up to the times of Tycho Brahe and Kepler.Every 20 years, successive Great Conjunctions move retrograde ~120°. Sequential Conjunctions appear as triangular patterns. They repeat after every third Conjunction; they return after some 60 years to the vicinity of the first. These returns are observed to be shifted by ~8° relative to the fixed stars; no more than four of them occur in the same zodiac sign. Typically, Conjunctions occur in one of the following Triplicities or Trigons of Zodiac signs:
After about 220 years the pattern shifts to the next Trigon; in ~900 years, the pattern returns to the first Trigon.
To each triangular pattern, astrologers have ascribed one from a series of four elements. Particular importance has been accorded to the occurrence of a Great Conjunction in a new Trigon, which is bound to happen after ~240 years at most. Greater importance is attributed to the beginning of a new cycle, which may occur after all four Trigons have been visited, which occurs in ~900 years.
Typically, medieval astrologers used 960 years as the length of the full cycle, because, in some cases, it took 240 years to pass from one trigon to the next. If a cycle is defined by when the Conjunctions return to the same right ascension rather than to the same constellation, the cycle is only ~800 years, because of axial precession. Use of the Alphonsine tables apparently led to the use of precessing signs; Kepler gave a value of 794 years, which created 40 Conjunctions.
Up to the end of the 16th century, despite the inaccuracies and some disagreement about the beginning of the cycle, the belief in the significance of such events generated a steady stream of publications. In 1583, the last Great Conjunction occurred in the watery trigon. It was widely supposed to herald apocalyptic changes. In 1586, a Papal Bull was issued against divinations. By 1603, public interest rapidly died, because nothing really significant had happened with the advent of a new Trigon.
| Symbol | Harmonic | Angle | Name |
| 24px | 1/1 | 360° | Conjunction |
| 24px | 1/2 | 180° | Opposition |
| 24px | 1/4 | 90° | Square or Quartile or Quadrate |
| 1/8 | 45° | Octile or Semisquare | |
| 3/8 | 135° | Trioctile or Sesquiquadrate | |
| 1/16 | 22.5° | Sexdecile or Semioctile | |
| 3/16 | 67.5° | Sesquioctile | |
| 5/16 | 112.5° | Quinsemioctile | |
| 7/16 | 157.5° | Sepsemioctile | |
| 24px | 1/3 | 120° | Trine or Trinovile |
| 24px | 1/6 | 60° | Sextile or Semitrine |
| 1/12 | 30° | Duodecile or Semisextile | |
| 5/12 | 150° | Quincunx or Quinduodecile or Inconjunct | |
| 1/24 | 15° | Quattuorvigintile or Semiduodecile | |
| 5/24 | 75° | Squile | |
| 7/24 | 105° | Squine | |
| 11/24 | 165° | Quindecile or Contraquindecile | |
| 1/5 | 72° | Quintile | |
| 2/5 | 144° | Biquintile | |
| 1/10 | 36° | Decile or Semiquintile | |
| 3/10 | 108° | Tridecile or Sesquiquintile | |
| 1/15 | 24° | Quindecile or Trientquintile | |
| 2/15 | 48° | Biquindecile | |
| 4/15 | 96° | Quadraquindecile | |
| 7/15 | 168° | Sepquindecile | |
| 1/20 | 18° | Vigintile or Semidecile | |
| 3/20 | 54° | Trivigintile or Sesquidecile | |
| 7/20 | 126° | Sepvigintile | |
| 9/20 | 162° | Nonvigintile | |
| 1/40 | 9° | Quadragintile or Semivigintile | |
| 1/7 | 51.43° | Septile | |
| 2/7 | 102.86° | Biseptile | |
| 3/7 | 154.29° | Triseptile | |
| 1/14 | 25.71° | Semiseptile | |
| 3/14 | 77.14° | Tresemiseptile or Sesquiseptile | |
| 5/14 | 128.57° | Quinsemiseptile | |
| 1/9 | 40° | Novile | |
| 2/9 | 80° | Binovile | |
| 4/9 | 160° | Quadranovile | |
| 1/18 | 20° | Octodecile or Seminovile or Vigintile | |
| 1/36 | 10° | Trigintasextile | |
| 1/11 | 32.83° | Undecile or Undecim or Elftile | |
| 2/11 | 65.45° | Biundecile or Bielftile | |
| 3/11 | 98.18° | Triundecile or Trielftile | |
| 4/11 | 130.91° | Quadundecile or Quadrelftile | |
| 5/11 | 163.63° | Quinundecile or Quinelftile |