☉Western astrology · 5 min
An aspect is the angle between the ecliptic longitudes of two celestial bodies. According to tradition, certain angles "resonate", linking the roles of the two planets. Aspects give the chart its dynamics: they show how the various inner "actors" affect one another.
The major aspects
The classical (Ptolemaic) five are described by tradition as follows:
- Conjunction (0°): the two planets' roles merge; strong and concentrated, harmonious or awkward depending on the signs and planets.
- Sextile (60°): easy cooperation, an opportunity that nevertheless requires initiative.
- Square (90°): friction, tension, a challenge that pushes towards action.
- Trine (120°): natural harmony, sometimes "too easy" and therefore an unused talent.
- Opposition (180°): polarity, swinging between two extremes, the task of balancing.
Minor aspects include the semi-sextile (30°), the semi-square (45°), the quincunx (150°) and the sesquiquadrate (135°). They are used with less tradition behind them and with narrower orbs.
What is an orb?
The permitted deviation from the exact angle is called the orb. If the Sun and Mars are 87° or 93° apart, the square (90°) holds with an orb of 3°. In tradition, the tighter the orb, the stronger the aspect. Orb sizes are not standardised: most authors allow 6 to 10 degrees for the major aspects and 1 to 3 for the minor ones, and more for the Sun and Moon. A distinction is made between applying and separating aspects, depending on whether the faster planet is still approaching the exact angle or has already passed it.
Why does everybody have many aspects?
A little arithmetic: among ten bodies there are 45 planet pairs. With an 8° orb, a given pair forms one of the major aspects in roughly a third of cases (about 36%). That means an average of 15 to 16 aspects per chart. A chart with many aspects is therefore ordinary, not special. This is why it makes sense to emphasise tight, exact aspects and not to believe that every line carries a unique meaning.
Aspect patterns
Certain configurations have names of their own: the grand trine (three planets 120° apart), the T-square (two planets in opposition, a third squaring both) or the grand cross. Tradition sees these as strong, organised themes, but they too are common, and their occurrence is simply a consequence of the mathematics.
How to read them
1. Start with the tight aspects (under 3°). 2. Always read the two planets' roles together with their sign and house positions. 3. Do not call a "tense" aspect bad and a "harmonious" one good; in traditional usage the square is often the engine of development. 4. Treat it as a hypothesis: "Do I recognise this kind of inner tension?"
Scientific status
In scientific studies no empirical evidence has been found for the meanings of aspects either: the relationships between traditional descriptions and measured personality traits or life events were not confirmed under controlled conditions. Aspects can be used as a cultural and symbolic language, keeping the Barnum effect in mind.