Introduction to the Lunar Nodes

Rahu (the North Node) and Ketu (the South Node) are not physical planets but mathematical points - the intersections of the Moon's orbital path with the ecliptic. In Vedic astrology they are treated as full-fledged **shadow grahas** (Chaya Grahas) with enormous influence.

### Astronomical Basis

The Moon's orbit is inclined approximately 5.1 degrees to the ecliptic. The two points where the Moon crosses the ecliptic are the lunar nodes: - **Rahu (North Node)**: where the Moon crosses from south to north of the ecliptic - **Ketu (South Node)**: where the Moon crosses from north to south

### Motion

The nodes move **retrograde** through the zodiac continuously, completing one cycle in approximately **18.6 years**. They spend roughly **18 months** in each sidereal sign.

### Mythological Basis

In the Samudra Manthan (churning of the cosmic ocean) myth, the demon Svarbhanu disguised himself as a god and drank the nectar of immortality. The Sun and Moon recognized him and alerted Vishnu, who severed his body with the Sudarshana Chakra. The head became **Rahu**, the tail became **Ketu** - both immortal but forever separated. Rahu perpetually tries to swallow the Sun and Moon, causing eclipses.

### Key Principle

Rahu and Ketu represent the **karmic axis** in Vedic astrology: - **Rahu**: what the soul craves and must experience in this life (unfulfilled desire) - **Ketu**: what the soul has already mastered in past lives (innate skill, detachment)