Aspects depend upon the angular distance between two planets or the distance between a planet and an important point in the horoscope such as an angle or house cusp, the Moon's Nodes or the Part of Fortune.

Aspects define planetary interaction. Planets in aspect influence each other's action according to the type of aspect and the nature of the planets forming the aspect. The relationships that planets bear to each other through aspects in the natal horoscope constitute patterns of experience and development that are unique to the individual. Aspects give the astrologer a more complete picture of planetary influence in the horoscope.

All aspects are defined by a specified number of degrees, which separate two points in the zodiac. The point at which an aspect is exact to the degree and minute is termed partile. An aspect that is within 1° of partile, is called an exact aspect; however, an aspect need not be exact to be effective. The number of degrees by which an aspect may vary from partile is called the orb of influence. An aspect that is not exact but still falls within the allowable orb is termed a platic aspect. The closer an aspect is to partile (the smaller the orb), the stronger its influence. Aspects fall into two general categories, major and minor. Major aspects are more powerful and influential than are minor aspects.

The orbs for major aspects between outer planets and the Angles, Nodes, or Part of Fortune are 8°. The aspects for the inner planets (those which rotate more rapidly around the Zodiac) are calculated on a 5-6° orb. Smaller orbs are used when calculating progressed charts. (Some controversy exists from differing schools of astrology as to acceptable orb degrees. Some are more strict. We teach a more liberal form).

Name of Aspect	Degrees Apart	*Symbol*	*Meaning*
CONJUNCTION	0° Two planets close to the same degree and usually in the same sign		Powerful. A conjunction is the strongest aspect in astrology. It is usually a beneficial influence, though not necessarily so. If the planets have other difficult aspects in the chart, a conjunction may intensify them. A conjunction means the two planets involved have a powerful influence and are a focal point in the chart.
TRINE	120° Two planets 120° apart		Most harmonious. A trine is the most favorable aspect, bringing advantage and ease. The only problem is that too many trines in a chart may make a person weak and lazy.
OPPOSITION	180° Two planets 180° apart		Unharmonious. An opposition brings strain, discordance, or separation. Modern astrologers look at oppositions less negatively than they were regarded in ancient times. Oppositions in a chart are thought of as exterior (not from within) challenges to growth and achievement.
SEXTILE	60° Two planets 60° apart		Harmonious and favorable. A sextile brings opportunity. Unlike trines, sextiles require effort on the part of the native to work their beneficial influence.
SQUARE	90° Two planets 90° apart		Challenging and stressful. A square places obstacles and teaches lessons. This aspect usually indicates an area where the person can develop drive and strength of character by overcoming difficulties.

Minor (less powerful) aspects were first introduced early in the 17th century by Johannes Kepler, the renowned astronomer who is called the father of modern astrology, and by Jean-Baptiste Morin, a French mathematician and astrologer.

QUINCUNX	150° Two planets 150 apart	Originally classified as mildly adverse, the modern tendency is to consider its influence unpredictable and also more powerful than first thought. Some astrologers connect a quincunx with health problems; others say it brings "offbeat wisdom." A quincunx (150°) is a somewhat difficult aspect to integrate. The signs involved are different in element (water and air), polarity (yin and yang), and quality (cardinal and fixed), requiring an adjustment on three levels.
SEMISQUARE	45° Mildly adverse. Two planets 45° apart	Brings tension that precipitates events but is much less powerful than a square.
SESQUISQUARE	135° Mildly adverse. Two planets 135°apart	Similar influence to a semisquare (sometimes called a SESQUIQUADRATE).
SEMISEXTILE	30° Two planets 30° apart.	Mildly favorable. Brings opportunity but is much less powerful than a sextile.

Aspects are classed as hard (difficult) or soft (easy). Hard aspects stimulate action and induce motivation. Except for the conjunction, all hard aspects are disharmonious to some extent depending upon the strength of the aspect and the natures of the planets involved. These aspects create tension, friction or difficulties, which in turn produce activity and choices. The conjunction may be harmonious or disharmonious; either way, they stimulate planetary energies as do all hard aspects. Soft aspects generate harmony; they blend planetary energies smoothly and create conditions of ease and accord. They partially mitigate difficulties or hardships imposed by inharmonious aspects and contribute to "good luck."

Planetary action in a horoscope depends largely upon the aspects formed. The same aspect will not have the same effect in one horoscope as in another. All relevant factors, including other aspects, are weighed in determining the influence a given aspect exerts in a particular horoscope. In any case, the essential characteristics of an aspect remain unchanged although its significance may be modified by other factors.

Several aspects may combine to form a particular pattern or configuration. The influence of combined aspects may alter or extend that of the aspects considered individually.

Stellium or multiple conjunction: This configuration is composed of three or more planets that form a series of conjunctions. Some authorities reserve the term stellium for those series of conjunctions that occur within one sign; the term multiple conjunction is then applied to a series of conjunctions that extend from one sign into another. The stellium focuses planetary activity in accordance with the houses and signs involved. A member of a stellium is influenced by aspects made to other members of the stellium even if the orb is too wide to normally include that planet. This is called aspect by association. Associative aspects broaden the influence of the initial aspect.

T-Square: A T-square is formed when two planets in opposition both square the same third planet. The squared planet acts as a focal point for the tension generated by the planets in opposition; it represents the means of resolving difficulties and surmounting obstacles inherent in this configuration. A cardinal Tsquare is one in which each planet occupies a different sign of the cardinal quadruplicity; it prompts impatience and urges decisive, often hasty action, which can create greater problems than existed initially. A fixed T-square implies endurance and resistance in the face of adversity, but it can produce inflexibility, which inhibits progress. A mutable T-square gives more leeway. The easiest course may be to try to avoid or ignore difficulties, but such action does nothing to resolve them. T-squares create conflict but they also spark ambition. A dissociate T-square (one that contains signs belonging to mixed quadruplicities) does not carry the impact that a cardinal, fixed, or mutable T-square wields. The symbol for a T-square is "T"; the crossbar denotes the opposition and the vertical line indicates the planet, which is square to both ends of the opposition.

Grand Square or Grand Cross: This configuration consists of four squares and two oppositions and contains at least one planet in each member of the same quadruplicity. This formation differs from that of the T-square with the addition of another planet placed opposite the "squared" planet. The extreme tension produced by the grand square creates a state of constant struggle and crisis. The affairs of the planets and houses involved undergo continuous upheaval; difficulties are consistent with the occupied quadruplicity. There is no focal planet in this configuration; each planet is under stress. The planet in the grand square that forms the largest number of favorable aspects with other planets is the key to partial resolution of problems. A trine or sextile is extremely helpful here. A dissociate (mixed) grand square signifies conflict as described by the individual aspects, but it is not as difficult as a cardinal, fixed or mutable grand square.

Grand Trine: This configuration is formed when three planets that occupy different signs of the same triplicity form mutual trines. A most fortunate combination, it indicates ease and a smooth flow of planetary energies. A grand trine does much to alleviate the strain produced by adverse aspects. The affairs of the planets and houses that are affected by the grand trine bring benefits and pleasure. A grand trine that is placed in fire signs confers inspiration and creativity; an earth grand trine is associated with material blessings; an air grand trine enriches intellectual expression and mental development; a water grand trine stresses compassion, receptivity and responsiveness. A grand trine composed of mixed elements (dissociate) lacks cohesiveness; nonetheless, three trines in a horoscope are certainly advantageous.

Yod: A yod occurs when two planets in sextile both form a quincunx with the same third planet. The planet that is in quincunx with the other two represents the action point of the yod; the point directly opposite in the zodiac is the reaction point. The reaction point will be at or near the midpoint of the two planets in sextile. Planetary action induced at the action point produces consequences at the reaction point; the effect influences all three planets as well as the affairs of the house that contains the reaction point. The yod has a karmic connotation; the action point represents cause, the reaction point shows effect. The yod is associated with circumstances not of one's own making; one shapes destiny in the affected areas according to how conditions are met. The symbol for the yod is 'Y.' The arms of the Y represent the planets in sextile; the vertical line indicates the planet to which the other two are quincunx.