Primary directions

Primary directions are the oldest predictive technique in Western astrology, used from Ptolemy to the Renaissance. They follow the daily rotation of the sky after birth: each degree that a planet (or its aspect) needs to rotate to reach an angle of the chart corresponds to about one year of life. The arrival of a planet at the Ascendant or Midheaven marks a key year.

Sources: Ptolemy, Tetrabiblos III; Placidus de Titis, Primum Mobile (1657); Martin Gansten, Primary Directions (2009).