| Well, a nominative is simply the proper name for the constellation. The genitive is the possessive form. This is used to specify the names of the stars, for instance, the brightest star in Orion, Betelgeuse, is also known as "Alpha Orionis". "Orionis" is the genitive form of Orion. Likewise, the star I am researching, which is located in the constellation Cepheus, is called "V402 Cephei", where "Cephei" is the genitive form of Cepheus. Click here to see a list of all 88 constellations in their nominative and genitive forms. |