A conjunction is an angle of approximately 0-10°. An orb of approximately 10° is usually considered a conjunction, however if neither the Sun or Moon is involved, some consider the conjunction to be a separation (orb) of only about 0±08°. This is said to be the most powerful aspect, intensifying the effects of the involved planets mutually — and being a major point in the chart. The planets will act together to outside stimulus and act on each other. The essential feature of a conjunction is that each planet brings out a characteristic in accord with its own nature out of the other planet. This may probably be difficult to achieve without the aid of the other planet. This process, however, will also cause each planet involved to lose some of its true characteristics. For example, a person with a conjunction of Mercury and the Planets in astrology Moon will find it easy to talk (Mercury) about his or her feelings (Moon) and rationalize them. However, due to their intellectual approach to emotions, it follows that their feelings also lose some depth, therefore, these people cannot handle heavy emotional demands. On the other hand, the involvement of the emotions (Moon) in the rational thinking process (Mercury) makes it easy for the person to think and communicate with sensitivity and consideration. This ability can, however, take away some of the objectivity (Mercury) from the thinking process due to biases from loyalties, emotional attachments, and so on (Moon).
Whether the union is to be regarded as "positive" or "negative" depends upon what planets are involved: Venus, Jupiter and the Sun, in any possible combination, is considered the most favourable scenario (and all three actually met on November 9–10, 1970, for example), while the most unfavourable configurations involve Mars, Saturn, and/or the Moon (with all three conjoining on March 10 in that same year). If the planets are under stress from other configurations, then the conjunction will be said to intensify the stress. When a planet is in very close conjunction to the Sun it is referred to as cazimi; when a planet is moderately close to Sun, it is said to be combust. The Sun and Moon are in conjunction monthly during the New Moon.
A sextile is an angle of 60°. A separation (orb) of 60±04° is considered a sextile. The sextile has been traditionally said to be similar in influence to the trine, but of less significance. It indicates ease of communication between the two elements involved, with compatibility and harmony between them, but only provides opportunity, requiring effort to gain its benefits. See information on the semisextile below.
A square (abrv. SQr or Squ) is an angle of 90° (1/4 of the 360° ecliptic, or 1/2 of an opposition [180°]). An orb of somewhere between 5° and 10° is usually allowed. As with the trine and the sextile, in the square, it is usually the outer or superior planet that has an effect on the inner or inferior one. Basically, the square's energy is similar to that of a trine but it is intensified to such an extent that the energy is said to be stressful. For example, Mercury square Saturn indicates practicality and prudence with thoughts and communication, concentrating on practical matters. It is also indicative of caution in planning and other mental tasks. However, the square between those planets indicates mental restraint, excessive censoring of communication and overemphasis on trivial details. It also indicates pessimism and a stilted and fearful approach to life. The square is said to indicate strain, tension, frustration, inhibitions, disruption and inner conflict. However, it can become a source of energy and activation to a person determined to overcome limitations, presenting challenges to achievement and an opportunity to develop strength of character. See the information on the semisquare and sesquiquadrate below. The square is also sometimes known as the quartile.
A trine (abrv. Tri) is an angle of 120° (1/3 of the 360° ecliptic). A separation (orb) of 120±04° is considered a trine. The trine indicates harmony, and ease of expression, with the two elements reinforcing each other. The trine is a source of artistic and creative talent, which is innate. The trine has been traditionally assumed to be extremely beneficial, providing ease even if undeserved, but it can be a 'line of least resistance' to a person of weak character. Too many trines are said to make a person weak and unable to cope with adversity. Complacency can also prove to be a problem. Due to the harmony bestowed by the trine, the person may not feel the need to develop the gifts given by this aspect, thus it follows that the person has no need to satisfy a need and supply what is lacking because it is already satisfied from the time of his or her birth. The essential meaning of the trine is momentum. It thus indicates situations or conditions which continue as they are without much input of energy and that tend to build upon themselves. It shows accumulation or accretion,continuance, balance, increase, self-perpetuation and stability. Although the trine is generally considered a "soft" or "good" aspect, if the two planets involved are both malefic by nature, or are planets poorly conditioned in the horoscope under consideration, the aspect may indicate rather uncomfortable conditions which persist and build on themselves. The aspect is purely personal in nature, and shows a person as he acts independently of the world in pure self-expression. It is therefore said to indicate natural talent.
An opposition (abrv. Opp) is an angle of 180° (1/2 of the 360° ecliptic). An orb of somewhere between 5° and 10° is usually allowed. Oppositions are said to be the second most powerful aspect. It resembles the conjunction although the difference between them is that the opposition causes exaggeration as it is not unifying like the conjunction but instead exalted. So the fact that the opposition creates a dynamic and exalted energy between the planets involved isn't as clearly negative as for instance the square, but it can be indicative of tension, conflict or confrontation, due to the between the two signs involved if not channeled constructively. If channeled constructively however the individual may use it as a creative and energetic power source. The Sun and Moon are in opposition monthly during the full moon.