Do Zodiac Signs Change Over Time?
In Western astrology, zodiac signs are based on the tropical zodiac, which divides the sky into twelve equal 30-degree segments starting at the vernal equinox. Because this system is tied to seasons rather than star positions, the dates and boundaries of the signs do not change over time for most astrological practice.
What About the Precession of the Equinoxes?
The Earth’s axis wobbles slowly over about 26,000 years, a movement called precession. This shifts the background constellations relative to the tropical zodiac. As a result, the Sun may appear in a different constellation than the one associated with a sign, which is why some people see news about a "new" or "changed" zodiac sign.
Are There 13 Zodiac Signs?
Some people point to Ophiuchus, a constellation the Sun passes through, as a possible 13th sign. However, Western astrology uses the tropical zodiac with twelve equal signs, not the actual astronomical boundaries of constellations. Most astrologers do not recognize Ophiuchus as a zodiac sign.
For more on the tropical zodiac and constellations, see astro.com zodiac data.
