Diurnal ("daily") may refer to: Diurnality, the behavior of an animal that's active in the daytime Diurnal motion, the apparent motion of stars around the Earth Diurnal phase shift, a phase shift of electromagnetic signals Diurnal temperature variation In astrology: Diurnal chart, a chart for a given date, based on the natal chart Diurnal planet, a planet in a sect for which the Sun's above the horizon Diurnal sign, a sign in the zodiac Diurnal arc, time expressed as right ascension… (More on Diurnal)