Chandra

Chandra, the Moon, is the second graha and, with the Sun, one of the two luminaries jyotisha weighs most heavily. Its presiding deity is Chandra, its gemstone is the pearl, its element is water, and its Vimshottari period is ten years. In jyotisha Chandra signifies the mind (manas), the emotions, the mother, and the public, so central that many Vedic charts are read as much from the Moon's sign as from the ascendant. It is classed as benefic when waxing and full, weaker when waning and dark, since its strength tracks the light it carries. Chandra rules the sign Karka (Cancer) and is exalted in Vrishabha (Taurus). Its condition governs emotional steadiness and the felt quality of life. These are traditional significations rather than statements about the physical Moon, whose light is in fact reflected sunlight, a fact the tradition's waxing-and-waning rule incidentally mirrors.

The word graha itself comes from the Sanskrit root grah-, to seize or grasp, so that the nine grahas of jyotisha are properly the seizers rather than planets in the modern astronomical sense, a name that lets Rahu and Ketu belong to the class while being no physical bodies at all, only the two points where the Moon's own path crosses the ecliptic. Chandra's place among the nine reached Sanskrit astrology from Greek horoscopy by way of the Yavanajataka, a versification of a Greek astrological text datable to roughly the second through fourth centuries CE, though the Moon itself was known and tracked in India long before that transmission; what arrived with the Yavanajataka was the horoscopic apparatus of dignities and exaltations, later systematised in texts such as the Brihat Parashara Hora Shastra, a compilation of roughly the seventh or eighth century CE ascribed to the sage Parashara.

Sources Brihat Parashara Hora ShastraSage Parashara (attributed) with Jyotihsastra: Astral and Mathematical LiteratureDavid Pingree, The Yavanajataka of SphujidhvajaDavid Pingree

A graha is not read in isolation but through the several tables that make up a Panchanga and a chart. It rules Monday in the seven-day week, which in the Indian tradition as in the European one is named for the seven visible grahas in the order of the planetary hours. It holds 10 years of the Vimshottari dasha cycle, and it is lord of three of the twenty-seven nakshatras, Rohini, Hasta and Shravana, spaced nine apart so that the nine grahas cover the twenty-seven exactly three times over.

The Vimshottari dasha system divides a notional lifetime of 120 years among the nine grahas in a fixed order, Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn and Mercury, with fixed lengths that sum to exactly 120. Which period a person begins life in is determined by the nakshatra the Moon occupied at birth, and how far through that period, by how far through the nakshatra the Moon had travelled.

In the scheme of dignities it is exalted in Taurus and in its fall in Scorpio, and dignity is what the classical rules for strength are built on, since a graha in its own sign or its exaltation is read as able to act and one in its fall as constrained.

The Moon carries more weight in this system than in most others, because it is the Moon's nakshatra at birth that fixes the whole dasha sequence, and the Moon's sign serves as a second reference point from which the chart is read in parallel with the ascendant. A birth time uncertain by an hour disturbs the ascendant and leaves the lunar reading intact, which is why the lunar apparatus is so heavily developed.