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. Gemini is a dual air sign ruled by Mercury, which is neutral to Ketu: the sign of talk, trade, news and quick thinking.
With Rahu in Sagittarius, belief, law and the big answer are what the world is reaching for. On the Ketu side, chatter and the small fact lose their pull. Old ways of talking and trading fall away. The lesson is that more information does not mean more understanding, and that silence teaches too.