Perhaps I'm oversimplifying, so I offer the words of a wise scholar:
“To preserve the coincidence of the vernal equinox in approximately correct relation to the Civil year, Caesar, with the assistance of Sosigines, introduced the Julian calendar about 46 B.C. It called for the intercalation of a day in specific years. The "last year of confusion," which preceded the introduction of this calendar was prolonged to 445 days. The arrangement was somewhat upset by Augustus Caesar, who insisted that his month of August have as many days in it as that of Julius. Pope Gregory XIII finally corrected the Julian calendar by what is known as the Gregorian rule of intercalation, which was adopted by all Christian countries, except Russia, which did not adopt it until 1918.”
In Western Astrology, one's Sun sign is determined by the position of the Sun at the moment of your birth, as seen from Earth. When every fourth year adds an extra day to the calendar, the leap years alter the dates of each Zodiac sign change only ever so slightly.
What does Leap Year suggest for your horoscope?It establishes that every four years, we welcome a special Pisces birthday! This Leap year, February 29th, we find the Sun in imaginative Pisces, the emotional Moon, stabilized in Taurus, forming a beneficial Sextile to Pisces ruler Neptune. Creativity and psychic awareness run high — calm, thoughtful energies prevail.
Leap year babies (Leaplings) are born near the tenth degree of Pisces. Very often possessing a magical sixth sense, their energy is artistic, intuitive and unique. Leapers can celebrate their Quinceanera (15th birthday) when the rest of us become senior citizens, and Leapling Pisces people bring out the best in others with their easy gratitude, willingness to explore, and a sense of wonderment!