Swan (myth. and astron.), a beautiful constellation in the Milky-way, which may be readily known from the five bright stars, arranged in the form of a cross, of which it is composed. It is situated between Cepheus and Vipes, to the east of the Lyre. On bright wintry nights the naked eye may count a hundred and fifty stars in this large constellation. The Swan commemorates the form chosen by Jupiter when he deceived Nemesis and Leda, or possibly the singing swan, sacred to Apollo, into which Orpheus was, at death, transformed.