Ketu is the Moon's south node, a shadow planet with no body of its own. It stands for letting go, the past, sudden endings and the turn inward. It moves backward through the zodiac, and Rahu always sits in the opposite sign, reaching for what Ketu releases. Sagittarius is a dual fire sign ruled by Jupiter, a friend to Ketu, so the planet is at ease here: the sign of faith, teachers, law and long journeys.
With Rahu in Gemini, news, trade and the newest way to talk are what the world is reaching for. On the Ketu side, old belief and the authority of teachers lose their hold. Faith turns personal. The lesson is that a belief worth keeping is one you have tested yourself.