Graha

The Sanskrit word graha (planet) comes from a root meaning "to seize": a graha is something in the sky that takes hold of life on Earth. Jyotish counts nine of them. Seven can be seen: the Sun, the Moon, Mars, Mercury, Jupiter, Venus and Saturn. The other two, Rahu and Ketu, are not bodies at all.

The nine grahas

The table lists them in the order hora shows them, with the two letters that stand for each in the drawn chart. The lagna (ascendant), which is not a graha, is marked La.

Rahu and Ketu

The Moon's path around the sky is tilted against the Sun's, so the two paths cross at two opposite points, the lunar nodes. Rahu is the node where the Moon crosses northward, Ketu the one where it crosses southward, so Ketu always stands exactly 180° from Rahu. Eclipses happen only when the Sun and the Moon are near these points. Nothing is there to see: Rahu and Ketu are chaayaa grahas (shadow planets), points found by calculation, yet a chart reads them as it reads the other seven.

A node can be calculated from the Moon's average motion or from its actual, slightly wavering one. The Node type field on the home page chooses between the two: mean, the default, or true.

Why not Uranus, Neptune and Pluto

The telescope has found three more planets, and some astrologers have added them to Vedic charts. The book does not (chapter 1, § 1.5): it keeps to what the seers of Jyotish taught, and none of them used these three. hora follows the book and neither calculates nor shows them.

More points in a chart

Besides the nine grahas, a chart holds points that are calculated rather than seen. The most important is the lagna, the point of the zodiac rising in the east at the moment of birth; it is placed among the grahas but is not one of them. The book brings in two more kinds later: upagrahas (sub-planets), eleven moving points, in chapter 4, and special lagnas (special ascendants), points used the way the lagna is, in chapter 5. hora does not calculate these yet.

Retrograde grahas

Seen from the Earth, a graha usually moves forward through the rasis (signs), in the order of the zodiac. Mars, Mercury, Jupiter, Venus and Saturn now and then seem to halt and go backward for a while, an effect of watching them from the Earth, which is itself moving round the Sun. A graha in that state is retrograde. The Sun and the Moon never are. The nodes move backward nearly all the time: the mean nodes always, the true nodes with short spells of forward motion.

hora marks a graha retrograde when its longitude is decreasing at the moment of birth, by the same rule for all nine, the nodes included. In the table, an R follows its degree; in the drawn chart, a raised R follows its letters. With the mean nodes, then, Rahu and Ketu always carry an R; with the true nodes, now and then they do not.

Next comes the rasi, the twelve parts of the zodiac the grahas move through.

Book reference: P.V.R. Narasimha Rao, Vedic Astrology: An Integrated Approach, chapter 1, § 1.3.1. Where to get the book