As the planets move around the zodiac sky they form angles between them and then they are said to be in aspect to each other. Aspects are said to combine the energies of the planets involved and act on individuals. These would be potent forces that act on us. Some of the aspects are benefic while some are malefic also called as soft aspects and hard aspects.
Aspects don't have to be exact to be effective, although the effect is strongest when the planets are at the precise angular distance apart. There is a leeway or "margin of error" allowed when calculating aspects and that is called the "orb".
The big aspects between the slow-moving outer planets are some of the most potent astrological influences we encounter. Some of these aspects can affect us for months, even years, at a time, shaking our lives to the core as they transform us at deeper levels. The aspects between the moving planets for all the 12 months of the year 2018 are listed here:
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.