Lunar Nodes are nothing more than the points of conjunction between the Moon's orbit and the ecliptic (the path the Sun takes around the Earth). They are the mathematical points where the Sun, Moon and Earth align to create eclipses. Eclipse of the Sun is when the Sun and Moon are conjoined with Rahu or Ketu; while eclipse of the Moon occurs when the Sun and Moon in opposition are arbitrarily one with Rahu and the other with Ketu.
From another point of view, we can say. Rāhu and Ketu are two sides of the Moon. Or rather, the two extremes. In Vedic Astrology, the Moon represents the Mind (manas). Thus the two Nodes, Rāhu and Ketu, represent the two extremes of the mind. Two extremes that are always within us and pushing us in their directions.
In one respect, Nodes represent the mind's tendency to accept and reject, rāga-dveṣa. The mind goes toward acceptance of what gives us pleasure and rejection when that thing disappoints or shows its transient side. Thus the mind oscillates between Rāhu and Ketu. This duality is the source of our sufferings (BG 7.27) and a person who transcends it finds full grace (BG 2.64).
Let's make a brief analogy with the characters in the epic poem, Rāmāyaṇa, in which the protagonist Rāma, the symbol of righteousness, and the antagonist Rāvaṇa, the symbol of ego, clash in an adventurous pursuit that will result in a furious fight in which Rāma will regain possession of his wife Sītā.
Sītā symbolizes the soul imprisoned by the ego, Rāvaṇa, in the illusory city of Laṅkā, that is, in body and mind.
Sītā is also the energy of which this world is made. This energy-itself neutral, neither good nor bad-takes on different characteristics depending on how it is used: it can be used to serve the ego, Rāvaṇa, or to serve with love the Absolute, Rāma.
Rāhu takes us to Ravana, materialism, egoism, ego centering, burning desires; and Ketu takes us to Rāma, spirituality, service, compassion, devotion, renunciation.
Rāhu and Ketu are Nodes of the Moon; they are not independent. If there were no Moon, there would be no Rāhu and Ketu.
Rāhu is the reason why we are now in this world and serving this precise karma. And, at this level, we have to be grateful to him, because we have a rare human body.
Ketu is the point at which we can achieve spiritual liberation.