Ashwini

Ashwini is the first of the twenty-seven nakshatras, the lunar mansions of Vedic astronomy, and occupies the opening 0 to 13 degrees 20 minutes of the sidereal zodiac in Aries. Each nakshatra is a segment the Moon crosses in roughly a day, and the scheme is older than the twelve-sign zodiac in Indian usage. Its ruling planet in the Vimshottari cycle is Ketu, the Moon's descending node; its presiding deities are the Ashwini Kumaras, the twin horsemen and physicians of the gods; and its symbol is a horse's head. In jyotisha the mansion is read as Deva gana, classed among the divine-tempered stars, and is associated with swiftness, healing, and fresh beginnings, the qualities the twin horse-riders carry. These attributions are traditional readings within the astrological system rather than statements about the stars themselves; the underlying asterism lies near the head of Aries.

The relationship between this system and its two sibling lunar-zodiacs is worth stating plainly, because it is a genuinely open scholarly question. The twenty-seven Indian nakshatras, the twenty-eight Chinese xiu, and the twenty-eight Arabic manazil al-qamar all divide the ecliptic by the Moon's own motion, and Babylonian astronomy is often proposed as a common ancestor behind all three, though the transmission history between them has never been conclusively resolved; orientalist scholars have argued for transmission running in more than one direction and for independent development, without reaching agreement. Part of the difficulty is the count itself: the Moon's sidereal period is about 27.3 days, so 27 and 28 are both reasonable roundings, and an older 28-nakshatra list, with an extra mansion called Abhijit, is attested before the 27-fold count became standard.

Every nakshatra is quartered. The four padas, literally feet, are the smallest unit jyotisha divides the ecliptic into and the reason the system can say anything finer than thirteen degrees. Ashwini runs from 0 degrees 00 minutes to 13 degrees 20 minutes of the sidereal circle, and its four padas are three degrees twenty minutes each: the first from 0 degrees 00 minutes of Aries, the second from 3 degrees 20 minutes of Aries, the third from 6 degrees 40 minutes of Aries and the fourth from 10 degrees 00 minutes of Aries. The Moon crosses a single pada in roughly six hours, so a birth an afternoon apart can fall in two of them.

The arithmetic hides a coincidence that is not one. Twenty seven nakshatras of four padas make one hundred and eight divisions of the zodiac, and the navamsha, the ninth-part chart that jyotisha treats as the most important of all the divisional charts, also cuts the circle into one hundred and eight. They are the same cut. A pada is a navamsha, and naming the pada names the navamsha sign without any further calculation. The four padas of Ashwini fall in Aries, Taurus, Gemini and Cancer in that order.

Two cautions attach to those degrees. They are sidereal, measured from a fixed point among the stars rather than from the equinox, so they depend on the ayanamsha chosen to locate that point; the Lahiri, Raman and Krishnamurti values differ by up to about a degree, which is a fifth of a pada and enough to move a chart across a boundary. And the equal arcs are a scheme laid over the sky rather than a description of it: the star the nakshatra is named for sits somewhere inside its arc rather than filling it, and for several nakshatras that identification is itself disputed.