All stars but one can be associated with an IAU constellation. IAU constellations are areas of the sky.Although there are only 88 IAU constellations, the sky is actually divided into 89 irregularly shaped boxes as the constellation Serpens is split into two separate sections, Serpens Caput (the snake's head) to the west and Serpens Cauda (the snake's tail) to the east.mong the remaining stars, the nearer ones exhibit proper motion, so it is only a matter of time before some of them cross a constellation boundary and switch constellations as a consequence.