Sun signs are not arbitrary date blocks printed on magazine pages. They represent geometrical coordinates. In tropical astrology, 0° is locked to the March equinox. As Earth travels around the Sun, the solar position appears to advance across the ecliptic plane at an average rate of roughly 0.9856 degrees per day.
The Sun departs Aries and enters Taurus at exactly 30°00'00" ecliptic longitude. It remains there until hitting 59°59'59", after which it enters Gemini at 60°. Because Earth's orbit is elliptical, its speed varies slightly based on perihelion and aphelion points. This orbital eccentricity means the Sun takes around 30.5 days to complete this 30-degree arc, creating slight annual variations in the transition hours.
