## Why the Transition Date Can Shift Although May 20 is designated as the final day of Taurus, the precise moment the sun enters Gemini changes from year to year. This variation occurs due to two primary factors: * **Leap Years:** A standard calendar year has 365 days, but the Earth's actual orbit around the sun takes approximately 365.25 days. The addition of a leap year every four years corrects this discrepancy but causes the exact time of the sun's transition into Gemini to shift by a few hours each year. * **Time Zones:** The sun's entry into a new zodiac sign happens at one specific global moment. Depending on your geographic location and time zone, this transition might occur late in the evening on May 20 or early in the morning on May 21. Because of these shifts, individuals born on May 20 or May 21 are often referred to as being born on the "cusp."
## Astrological Sign vs. Astronomical Constellation It is also helpful to understand the difference between the astrological sign of Taurus and the astronomical constellation of the same name. The dates listed by Britannica (April 20 to May 20) are based on the tropical zodiac system. This system, established in antiquity, aligns the zodiac signs with the seasons of the Northern Hemisphere and remains fixed. However, due to the precession of the equinoxes—the slow, continuous rotation of the Earth's axis—the physical constellations have shifted over time. Astronomically, the sun currently passes in front of the constellation Taurus from approximately May 14 to June 21. Despite this astronomical shift, Western astrology continues to use the fixed tropical dates of April 20 to May 20.
## How to Verify Your Zodiac Sign If you were born on May 20 and want to confirm whether you are a Taurus or a Gemini, you can verify your sign by calculating a precise birth chart. To do this, you will need: * The exact date of your birth * The precise time you were born (to account for the sun's movement on that specific day) * The city and country of your birth (to determine the correct time zone) Using these details, a birth chart calculator can identify the exact degree of the sun at your time of birth, confirming whether you fall under Taurus or Gemini.
