The zodiac
The two zodiacs are 24° apart, and drifting further
The zodiac in a magazine horoscope and the one an Indian astrologer uses were once the same. The Earth’s slow wobble has pulled them apart, by about a day every seventy-two years.
The Plutto Magazine · 13 October 2026 · 2 min read
The Earth spins like a slightly tipped top, and like a top its axis slowly circles. One full circle takes about 25,800 years. Astronomers call it the precession of the equinoxes, and the Greek astronomer Hipparchus noticed it in the second century BC by comparing his star positions with ones measured about 150 years earlier.
Seasons or stars
Western astrology fixes the start of Aries to the March equinox, so its signs stay tied to the seasons: Aries always begins around 21 March. That is the tropical zodiac. Vedic astrology, Jyotish, fixes its signs to the stars themselves: the sidereal zodiac. Because of precession, the March equinox slides backwards against the stars by about one degree every seventy-two years, and the two zodiacs move apart.
For roughly four people in five, the Sun sits in a different sign in each zodiac.
The gap between them is the ayanamsa. On the Lahiri reckoning, the standard adopted by India’s Calendar Reform Committee in the 1950s and the most widely used in India, it is now a little over 24°. A sign is 30° wide, so anyone born in the first 24° or so of a tropical sign has their sidereal Sun in the sign before: roughly four people in five.
Which one is right?
Neither is a mistake. They answer different questions: one follows the year’s light and the seasons, the other the stars behind them. The so-called Age of Aquarius is the same drift, the equinox point backing out of Pisces towards Aquarius; astronomers do not agree on when, because the constellations have no fixed borders for it.
Plutto reads your chart in the zodiac your tradition uses, and the free calculator on this site shows your Moon sign in both.
In the app
How do you know?
Every claim opens to its working: the method, the positions, and how much your birth time matters.
Open PluttoSources
- Ptolemy, Almagest, Book VII (on Hipparchus and precession).
- Report of the Calendar Reform Committee, Government of India (1955).
- N. Capitaine et al., “Expressions for IAU 2000 precession quantities,” Astronomy & Astrophysics 412 (2003).
Plutto presents these traditions for reflection; it does not claim that astrology predicts events.
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