One of the most intriguing of the ancient legends tells how a band of heroes headed by Jason sailed off in search of the Golden Fleece. Among the heroes concerned in this expedition were Hercules and the heavenly twins Castor and Pollux. The ship they travelled in was called the Argo and fittingly enough Argo Navis used to be the largest in the sky. I say used to, because it was such an unwieldy constellation that in 1750 the French astronomer Nicolas Louis de Lacaille broke it up into 3 parts, Carina the keel, Puppis the stern and Vela the sails.