In yesterday's article, The Importance of Rahu in a Horoscope, by K.N. Rao he discussed how Rahu is a point of obsession in the chart, which can lead to our upliftment or downfall. It has the power to be a benefic influence, like a yogakaraka, or a malefic influence.
Rahu, the North Node of the Moon, is sometimes believed to be a planet that represents our dharma or life purpose. It represents the desires that bring us into incarnation. It represents new, unexplored territory on the soul's journey. Whereas, Ketu, the South Node of the Moon, represents the desirelessness that liberates us, that takes us out of incarnation, that frees us from the cycle of birth and death. Rahu represents strong desires and compulsions, usually of a materialistic, ego-centered, and/or addictive nature. It can give fame and wealth and it's common to see actors/actresses becoming famous during a Rahu dasha (planetary period).
However, when we're moved to follow our dharma, passion, or life purpose we become soul-centered, not ego-centered. We're compelled by inspiration not desire. Astrologically, it's the difference between the 3rd house, which represents what we 'want to do,' versus the 9th house, which represents what we are 'inspired to do.' It's the difference between doing something because it's fun, new and interesting, versus doing something because it inspires us, and gives our life meaning. Externally it could look the same, but internally it's a completely different experience.