Look up into the southern sky and you may see four constellations that used to be one. The modern constellations Carina, Puppis, Vela, and Pyxis are named among the 88 modern constellations. Combined, though, these four once made up Argo Navis, the largest of the 48 constellations catalogued by Second Century astronomer Ptolemy. Argo Navis, which was sometimes simply known as Argo, is the only one of those original 48 excluded from our contemporary 88.
The constellation was said to represent the Argo, the mythological ship sailed by Jason and the Argonauts in in the their quest for the golden fleece, a magical relic that conferred the right to rule on its holder.
Because Argo Navis was so much bigger than any of the other constellations, French astronomer Nicolas Louis de Lacaille broke it up into smaller pieces, Carina, the hull of the ship, Puppis, the stern, and Vela, the sails. He left off Pyxis, now known as the compass or, sometimes, the mast, but the stars in this constellation were all once included in Argo.
Together, these constellations contain more than 185 stars. Only Puppis includes any Messier objects, bright deep sky objects identified primarily by French astronomer Charles Messier during the 18th Century. These are M46, M47, and M93, all open clusters.
Other notable deep sky objects include the planetary nebula NGC 3132, known as the “Eight-Burst Nebula” or “Southern Ring Nebula,” and the so-called “Gum Nebula” in Vela. Carina contains several faint open clusters, while Pyxis is home to Henize 2-10, a dwarf galaxy that lies about 30 million light years away.
Constellations bordering the four parts of Argo Navis include Pictor, Volans, Chamaeleon, Musca, Centaurus, Hydra, Antlia, Columba, and Canis Major.
So head outside, look toward the southern sky, and let your imagination set sail!