Rahu

Rahu is the Moon's ascending node, the place where the Moon's path rises across the Sun's path in the sky. It is a point on the ecliptic with no disc of its own. The Brihat Jataka lists Tama (darkness), Agu and Asura as its names, and the Brihat Parashara Hora Shastra, in a Wikisource typing of unknown edition, includes Rahu in its list of nine grahas, after Saturn.

This is where the sources treat Rahu differently from the seven bodies. The Brihat Jataka gives the Sun, the Moon and the five visible planets a color, a taste, a friendship table, strengths, an exaltation and a sign or two, and it gives the nodes none of these. No sign is called Rahu's in the lists, and in the passages read for this site Rahu appears in the synonym list, in a list of directions as lord of the south-west, in the dasha scheme and in a few passing rules.

The Surya-Siddhanta, a treatise on astronomy, gives the node 232,238 revolutions in an Age of 4,320,000 years, in the contrary direction. That is the mean motion only, about one turn in 18.6 years, with no correction. The Indian ephemeris tabulates mean Rahu, and the calculator uses the mean node, with Ketu set 180 degrees away.

In the Vimshottari scheme, the 120-year timetable of periods, Rahu rules 18 years over Ardra, Swati and Shatabhisha. Iyer writes of the nine parts as presided over by the seven planets and by Rahu and Ketu, the two nodes of the Moon.