The twelve rashis

The zodiac, or rashichakra, is the belt of sky through which the Sun, the Moon and the planets appear to travel. Jyotish divides this 360° circle into 12 equal signs called rashis, each 30° wide. Almost every later idea in a horoscope — houses, lords, aspects, dashas — is built on these twelve divisions, so this lesson sets out their names, their measured boundaries and the qualities the tradition gives them.

Twelve signs of 30°

A rashi is a fixed 30° stretch of the zodiac. Counting from 0°, Mesha runs from 0° to 30°, Vrishabha from 30° to 60°, and so on until Meena ends at 360°, which is 0° again. A planet at 100°, for example, has passed three full signs (90°) and is 10° into the fourth, Karka; astrologers write this as 10° Cancer. Placing a graha in a sign is pure arithmetic. What the sign is said to signify is traditional interpretation.

• 1. Mesha — Aries (0°–30°)
• 2. Vrishabha — Taurus (30°–60°)
• 3. Mithuna — Gemini (60°–90°)
• 4. Karka — Cancer (90°–120°)
• 5. Simha — Leo (120°–150°)
• 6. Kanya — Virgo (150°–180°)
• 7. Tula — Libra (180°–210°)
• 8. Vrishchika — Scorpio (210°–240°)
• 9. Dhanu — Sagittarius (240°–270°)
• 10. Makara — Capricorn (270°–300°)
• 11. Kumbha — Aquarius (300°–330°)
• 12. Meena — Pisces (330°–360°)

Sidereal and tropical zodiacs

There are two ways to fix where 0° Aries lies. The tropical zodiac, used in Western astrology, starts at the point where the Sun crosses the celestial equator in March, the vernal equinox. The sidereal zodiac, used in Jyotish, ties the signs to the background stars. Because the Earth’s axis slowly wobbles (the precession of the equinoxes), the equinox point drifts backward against the stars by about 50 arc-seconds a year, roughly 1° every 72 years.

The gap between the two zodiacs is the ayanamsa. Today it is about 24°. To convert, subtract the ayanamsa from the tropical longitude: a Sun at tropical 15° Aries (15°) minus 24° gives 351°, which is 21° Pisces in the sidereal zodiac. This is why the Sun enters sidereal Mesha — Mesha Sankranti — around 14 April rather than at the March equinox.

Schools calculate the ayanamsa slightly differently. The Calendar Reform Committee set up by the Government of India, which reported in 1955, adopted the value now called the Lahiri ayanamsa, after the astronomer N. C. Lahiri, a member of the committee. It places the star Chitra (Spica) near 180°, the start of sidereal Libra, and it remains the official standard for India’s national almanac.

Ayanamsa choice is a tradition difference, not a matter of right and wrong. Other values in use, such as Raman’s or Krishnamurti’s, can differ from Lahiri by up to a degree or more, enough to move a planet near a sign boundary into the neighbouring sign. This site uses “Lahiri (calibrated)” by default and lets you select standard Lahiri; the methodology page explains both.

Elements, modalities and odd and even signs

Classical texts give each sign three repeating qualities. The elements (tattva) run in a cycle of four, the modalities in a cycle of three, and odd and even simply alternate, so each sign has its own combination.

• Fire (agni): Mesha, Simha, Dhanu.
• Earth (prithvi): Vrishabha, Kanya, Makara.
• Air (vayu): Mithuna, Tula, Kumbha.
• Water (jala): Karka, Vrishchika, Meena.
• Movable (chara): Aries, Cancer, Libra, Capricorn.
• Fixed (sthira): Taurus, Leo, Scorpio, Aquarius.
• Dual (dvisvabhava): Gemini, Virgo, Sagittarius, Pisces.

Odd signs — Aries, Gemini, Leo, Libra, Sagittarius and Aquarius — are called masculine (oja) and described as active. Even signs — Taurus, Cancer, Virgo, Scorpio, Capricorn and Pisces — are feminine (yugma) and described as receptive. So Simha, the 5th sign, is fire, fixed and odd. These labels feed later techniques: some divisional charts, for instance, are counted differently in odd and even signs.

The sign lords

Each rashi has a ruling graha, its lord (swami). The Sun and the Moon rule one sign each; the five other planets rule two each. Rahu and Ketu are not counted in this scheme; some later authors give them co-rulership of certain signs, but the usual reckoning uses only these seven.

• Mars: Mesha (Aries) and Vrishchika (Scorpio).
• Venus: Vrishabha (Taurus) and Tula (Libra).
• Mercury: Mithuna (Gemini) and Kanya (Virgo).
• Moon: Karka (Cancer).
• Sun: Simha (Leo).
• Jupiter: Dhanu (Sagittarius) and Meena (Pisces).
• Saturn: Makara (Capricorn) and Kumbha (Aquarius).

There is a neat symmetry. Starting from Leo and Cancer, ruled by the Sun and Moon, the lords run outward in the same order in both directions: Mercury (Virgo, Gemini), Venus (Libra, Taurus), Mars (Scorpio, Aries), Jupiter (Sagittarius, Pisces) and Saturn (Capricorn, Aquarius). Knowing the lords lets you name the ruler of any house once you know which sign falls there, which module 3 uses constantly.

Lagna, Moon sign and Sun sign

Three signs are usually read first. The lagna (ascendant) is the sign rising on the eastern horizon at the moment and place of birth; it changes on average about every two hours, faster or slower depending on the sign and the latitude, so it needs an accurate birth time. The Moon sign, often simply called the rashi, is the sign the Moon occupies; the Moon crosses a sign in about two and a quarter days. The sidereal Sun sign changes about once a month, near the middle of each calendar month.

The example above shows these three for your saved birth details, or for the sky right now if you have none saved. The signs and degrees are calculated; the character descriptions attached to them in the classical texts are traditional interpretation, and astrologers always read them together with the rest of the chart.