The Sanskrit word for planet is Graha. The english equivalent of the word Graha is however inadequate. European translators who wanted to understand Indian astronomical texts, two centuries ago, made the hurried assumption that the word Graha means Planet. They did not understand the nuances of the word Graha. The widespread use of the word planet in place of Graha by educated Indians today in the context of astronomy creates confusion. The best example of this is a reference to Chhaya Graha (Shadow planet). How can a shadow be a planet or how can a planet be shadowy?

An overview of a few Sanskrit words Agraha, Parigraha, Nigraha, Anugraha and Vigraha gives us a clue that the word Graha refers to the principle of holding something in place. According to Sri Sri Ravishankar, an expert on the terminology in Vedic texts, the whole universe is moving fast and whatever is holding this universe is called Graha (QNA Nov 2015). Planets are Grahas by this definition but so are Sun and Moon. The well known set of Nine (Nava) Grahas includes Sun and Moon. But this set also includes two Chhaya (Shadow) Grahas. Rudimentary comparison of Vedic and modern astronomy texts is enough to conclude that the Chhaya Grahas are a reference to the moon’s north and south nodes. Astronomers today use the idea of Moon’s north and south nodes to predict eclipses. Is Rahu then the north node and Ketu the South node?

Vedic texts do assign a more prominent personality to Rahu than to Ketu. Rahu is half bodied as per Vedic metaphor but so is Ketu. Sculptors made the lower half of Rahu’s body the tail of a snake in temple carvings. They gave Ketu the face of a Snake. The human half of Rahu and Ketu are the tangible halves of Rahu and Ketu. Let us seek clues from the eclipse phenomenon and the role of the shadows of the Earth and the Moon. Earth’s shadow is larger of the two. It originates on earth which supplies a physical body to creatures living on it. Moon’s shadow terminates on earth during an eclipse. It occupies a width of a mere 270 km on the Earth and fans out towards the sky.

Nineteenth century Researchers concluded that Hindu astronomy borrowed substantially from the Greeks as they did not find an explicit referenc to Rahu and Ketu in Jyotish astronomy texts. They did not try to explain why Dasa period assignment for Rahu in Jyotish astrology texts accuratey matched the rotational period of lunar nodes. The Dasa period idea is unique to Vedic sciences and predates Greek civilization. Vedic seers conveyed a part of knowledge about any phenomenon as stories. They conveyed the remaining part as abstractions which a modern scientist accepts as scientific. Vedic seers relied on intuitive insights from meditation as the seed for new theories. They then verified them by careful obervations of physical phenomenon. Appreciating the richness of Vedic scientific methodology begins with an openess to look past the commonly accepted English equivalents for Sanskrit words. The word Graha is a good example of this.