Astrological aspects say something about how two planets would cooperate or compete with each other. By examining aspects another part of the overall picture can be revealed from radix, relationship or an event chart. Aspect means the angle, in whch one planet (heavenly body) sees the other, taking into account the neccessary regards to polarities and modalities of the signs occupied by respective planets. In astrological practice this angle (it is enumerated as few values for major aspects) is depicted on a circular chart by simple connecting line between two planets only - as a rule it is colored - the length of it itself indicating the value (identity) of the aspect unlike the geometric convention. All these aspects have distinctive names. A trivial (but not as simple) aspect from geometric point of view is a conjunct whose line is tiny or none at all and which covers angles around zero degrees thus involving two planets which seen from the Earth take very near verticals. For the strength or even legitimacy of each aspect the following must be taken into account:
  • signs of both planets, their correlation and also polarity and modality
  • angle between the two verticals - the so called orb, whose value varies for each aspect and also differs with planets involved. Its value is from tens of angle minutes up to several angle degrees. With the possible exception of conjunct as just mentioned it is max. 12 degrees yet usually it is third up to half of this maximum and frequently two or three degrees only.
  • the difference of the altitude - elevations of the planets and both signs of the elevations over the projection plane
  • orbital velocity of both planets namely whether they are approaching or separating
  • the character of both planet and the exaltation or debilitation by the signs they occupy
  • disposition and reception correlation of the planets by signs and houses

Major aspects are:

  • conjunct
  • opposition
  • square
  • trigon
  • sextile

Minor (secondary but sometimes critical) aspects:

  • quincunx
  • quintile
  • semisquare
  • semisextile
  • semiquintile
  • quintile
  • biquintile
  • sesquisquare
  • septile
  • novile

Subtle aspects more considered in modern astrology of the last two centuries - these all have substantially less orbs to be valid

  • biseptile
  • triseptile
  • binovile
  • kvinovile
  • undecile
  • and its multiples

These angles come as a result of dividing whole circle by small integers or as small integral multiples of such divisions.
Aspects show a possibility or willingness with which both planets cooperate or also impossibility of any cooperation, and they describe the enmity in topics or areas covered by both planets (bodies) within given chart.
Například kvadratura naznačuje nemožnost kooperace mezi dvěma planetami, případně oblastmi, které tyto planety postihují, vytváří však značné napětí a motivaci, případně přitažlivost. Opozice představuje výzvu mezi dvěma doplňkovými koncepty, při které je snadnější konflikt než vstřícnost, avšak tuto druhou možnost opozice nepopírá.
Planety, které spolu stojí v legitimním trigonu, spolupracují zcela přirozeně, někdy i ke škodě věci. Vždy však záleží na všech uvedených faktorech, určité kombinace planet mohou kterýkoliv aspekt zcela devalvovat, zatímco u spojení jiných planet může být kvadratura přínosným prvkem - buď proto, že spolupráci znemožňuje, anebo protože vytváří zdravé napětí, bez kterého by nedošlo k žádné pozitvní aktivitě.