Why is the opposite constellation of Sagittarius Gemini?

Opposition does not mean that you are at odds, but that the positions of the two constellations on the astrolabe are exactly 180 degrees, that is, the positions of "opposition". Each constellation has its own "opposite" constellation, and there are six groups of "opposite" constellations on the astrolabe. Just look at the positions of Sagittarius and Gemini in this chart. Sagittarius (red arrow with a bar in the upper right corner of the astrolabe) Gemini (Gemini)

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