Argo Navis

Almost 2,000 years ago, the Greek astronomer Ptolemy compiled a list of the constellations visible from the northern hemisphere - 48 in all. All but one of those constellations is still in use today. And even the one that’s no longer in use is still around. It was so big, though, that it was chopped into three pieces.

Argo Navis represented the ship that carried Jason and the Argonauts on their adventures. The crew included 50 of the greatest heroes of ancient Greece, including Heracles - better known today by his Roman name, Hercules; the twins of Gemini; and Argus, the shipbuilder for whom the Argo was named.

The original constellation was huge - it covered about a quarter more sky than the second-largest constellation. In fact, the Argo was so big that celestial mapmakers had a hard time getting it on a single chart. Even so, the Argo remained whole until the 1700s, when Nicolas de Lacaille split it into three parts. He kept their heritage, though, by naming them for parts of the