in Astronomy, denotes the situation of the planets and stars with respect to each other.

There are five different aspects. 1. Sextile aspect is when the planets or stars are 60° distant, and marked thus *. 2. The quartile, or quadrature, when they are 90° distant, marked □. 3. Trine, when 120° distant, marked Δ. 4. Opposition, when 180° distant, marked ⊙. And, 5. Conjunction, when both in the same degree, marked &.

Kepler, who added eight new ones, defines aspect to be the angle formed by the rays of two stars meeting on the earth, whereby their good or bad influence is measured: for it is to be observed, that these aspects being first introduced by astrologers, were distinguished into benign, malignant, and indifferent; the quartile and opposition being accounted malign; the trine and sextile, benign or friendly; and the conjunction, indifferent.