The dynamic interactions between the various energies of life are represented on an individual level by the aspects in a natal chart that is, the angles between planets and between the Ascendant or Mid-heaven and the planets. Aspects are also formed by the planets that are in constant motion in the zodiac sky.
By studying the relative aspects of the current planetary positions and the aspects in ones' natal chart certain astrological observations can be made.
Aspects can be categorized in two groups:
Dynamic or Challenging Aspects
This refers to the square (90°), opposition (180°), quincunx (150 the conjunction (0°) and the semi-sextile (30°). These are also known as hard aspects and denote certain harsh or hard periods in our life.
Harmonious or Flowing Aspects
This refers to the trine (120°), sextile (60°), and some of the conjunctions (0°) (depending of the planets involved) and semi-sextiles (30°). These aspects are generally benefic.
Do you know that the planetary aspects are measured using a cosmolabe??. This cosmolabe was first made by Jacques Besson in 1567.