In astrology, an aspect is the relative angle between two heavenly bodies. These aspects are held to influence human affairs: the more exact the aspect is, the more important it is said to be. The difference between the exact aspect and the actual aspect is called the orb.
As an example, if an astrologer creates a chart showing the apparent positions of the heavenly bodies at the times of a person's birth (a natal chart), and the apparent angle between Mars and Venus is 92°, the chart is said to have the aspect "Venus square Mars" with an orb of 2° (the orb is 92 minus 90 = 2).
To the ancients, certain aspects and certain planets were either good (benefic) or bad (malefic). Modern usage is different from this, with less emphasis placed on simple divisions.
Major aspects are recognized by almost all astrologers.
The list of aspects below gives the exact value and the acceptable orb of each aspect. The orbs are subject of controversy among astrologers.
The major aspects are the conjunction, opposition, trine, square, and sextile.
- A conjunction is an angle of 0°. If one of the bodies is the sun or moon, a separation of 0±10° is considered a conjunction. If neither the sun or moon is involved, a conjunction is a separation of 0±8°. This is said to be the most powerful aspect, intensifying the effects of the involved planets. If the planets are afflicted, then the conjunction will be said to intensify this affliction.
- An opposition is an angle of 180°. A separation of 180±8° is considered an opposition. Oppositions are said to be the second most powerful aspect. They are looked on less negatively than in the past, providing challenges in life, but also providing an integrating link, like a backbone.
- A trine is an angle of 120°. A separation of 120± 8° is considered a trine. The trine is said to be extremely beneficial, providing ease even if undeserved. Too many trines are said to make a person weak and unable to cope with adversity. The ancients considered an abundance of trines as a sign of evil.
- A square is an angle of 90°. A separation of 90±8° is considered a square. The square is said to indicate strain, tension, and energy, presenting challenges to achievement and an opportunity to develop strength of character.
- A sextile is an angle of 60°. A separation of 60±6° is considered a sextile. The sextile is said to be similar in influence to the trine, but only provides opportunity, requiring effort to reap its benefits.
The minor aspects, introduced by Johannes Kepler, are considered of secondary importance. They are the quincunx, semisquare, sesquiquadrate, semisextile, and quintile.
- A quincunx is an angle of 150°. A separation of 150±3° is considered a quincunx. The quincunx is said to be of moderate but somewhat unpredictable influence, bringing strain. This aspect is also sometimes called the inconjunct, though this usage is technically incorrect.
- A semisquare is an angle of 45°. A separation of 45±2° is considered a semisquare. This aspect is considered a weaker version of the square.
- A sesquiquadrate is an angle of 135°. A separation of 135±2° is considered as sesquiquadrate, and is considered similar in influence to the semisquare.
- A semisextile is an angle of 30°. A separation of 30±2° is considered a semisextile. This is considered a weaker version of the sextile.
- A quintile is an angle of 72°. A separation of 72±2° is considered a quintile. This is considered similar to a semisextile, but effort is not needed to reap its benefits.
The parallel and antiparallel (or contraparallel) are two other aspects, which refer to degrees of declination above or below the celestial equator (rather than degrees of elevation in relation to the horizon). Most astrologers do not use them because all of the planets except Mercury and Pluto are always within 3 degrees of the ecliptic. They are considered strong influences, though not much research has gone into studying these particular aspects.
- Parallel: Same degree±0.5 This is similar to a conjunction, but usually provides benefits.
- Contraparallel. opposite Degree± 0.5 Said to be similar to the opposition, but weaker.
- Classical Use of the Aspects (http://www.skyscript.co.uk/aspects.html)
- Information on Astrological Aspects (http://www.skyscript.co.uk/aspects2.html)
- The Question of Orbs (http://www.skyscript.co.uk/aspectorbs.html)
- Astrological Aspects Explained (http://www.skyscript.co.uk/sunaspects.html)