In astrology, an aspect is an angle the planets make to each other in the horoscope, and also to the ascendant, midheaven, descendant and nadir. The aspects are measured by the angular distance along the ecliptic in degrees and minutes of celestial longitude between two points, as viewed from the earth. They indicate focal points in the horoscope where the energies involved are given extra emphasis. The astrological aspects are said to influence affairs on Earth according to millennia of astrological tradition.
As an example, if an astrologer creates a horoscope showing the apparent positions of the heavenly bodies at the times of a person's birth (a natal chart), and the apparent distance between Mars and Venus is 92°, the chart is said to have the aspect "Venus square Mars" with an orb of 2° (i.e., it is 2° away from being an exact square; a square is a 90° aspect). The more exact that an aspect is, the more important it is said to be according to astrological precedent and tradition. The difference between the exact aspect and the actual aspect is called the orb.