The essence
The Moon's orbit is tilted about five degrees to the ecliptic, the Sun's apparent path through the sky, so it crosses that path at two points. The North Node is where the Moon heads northward across it. The South Node, its exact opposite, is where the Moon heads south. These points have no mass and give no light, yet eclipses happen only when the Sun and Moon line up near them. The axis slides backward through the zodiac, completing a circle in about 18.6 years and spending roughly a year and a half in each sign.
Medieval astrologers called it the Dragon's Tail, cauda draconis. In Indian astrology it is Ketu, the headless body of a demon who drank the nectar of immortality before Vishnu cut him in two. The head, Rahu, is the North Node.
Evolutionary astrologers read the South Node as past-life memory, while others see early conditioning. Either way, its sign and house show competence you can't remember learning, like the Capricorn South Node who was running family errands at twelve.
