Astrology & myths · Hellenistic astrology · Ptolemy, Tetrabiblos I.7 (sect)
Day charts and night charts
Ptolemy sorted the planets into those of the day and those of the night. The Sun belongs to the day.
Sect
Ptolemy classes the Sun as diurnal, with the Moon and Venus nocturnal, linking day with heat and activity and night with moisture and rest.
Your sky decides it
Whether a given moment falls in the day is plain astronomy: is the Sun above the horizon? The answer for your place comes from the same calculation as this site's sunrise and sunset, whatever you make of the symbolism.
Is the Sun up where you are? →
Astrology and myth are presented here as symbolic and historical traditions, not as predictions. The sky's positions and times on this site are calculated the same way in every lens.
Sources
- LacusCurtius (Bill Thayer) Ptolemy, Tetrabiblos, Book I, ch. 4–24 (trans. F. E. Robbins, Loeb 1940) (opens in a new tab) for the Sun heats and somewhat dries (I.4); diurnal (I.7); house Leo (I.17); exalted in Aries, depressed in Libra (I.19) · checked 2 October 2026
- Cool Moon Facts How the Sun pages calculate for the engine, its definitions, its independent checks and its limits