Of the 48 constellations described in Claudius Ptolemy's Almagest, 47 survive to the current day. The sole exception is Argo Navis, the ship that carried the mythical Greek hero Jason and his fellow Argonauts to the end of the known world in quest of the Golden Fleece. Its stars ended up distributed among four nautically themed constellations: Carina, the Keel or Hull; Vela, the Sails; Puppis, the Poop Deck; and Pyxis, the Compass. Pyxis is small and dim, but Carina, Vela, and Puppis are all big, bright, and spangled with naked-eye star clusters. If you put them back together, they'd be the biggest constellation in the sky — much bigger than Ptolemy's original Argo, in fact. For shorthand, I will call the original constellation Old Argo Navis, and use Greater Argo Navis to denote modern Carina, Vela, and Puppis.
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