計都（Ketu）是古代印度天文學名詞，原本指月球之遠地點，為月行最遲之處。後來，這定義在古中國天文學中為月孛所繼承，計都的定義就變作月球軌道與黃道的升交點（據沈括）或降交點（據湯若望），這是月球穿越黃道的交會點，見黃白交點／月球交點。
外部連結
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