The etymology is implicit in Aratus, but pinpointed by a scholion (see Parallels). It seems to be the etymology of ἄστρον, but it is indeed the etymology of ἀστήρ, which shares with the verb the sequence [stēr]. It is not clear whether ἀστήρ was understood as a derivative of στηρίζω with "adjunction" of the [a] or as a compound with the intensive alpha, or as a compound with the privative alpha (the latter analysis is explicit in the D Scholia, see Parallels). As usual, the privative / intensive ἀ- can lead to two opposite justifications. With the intensive prefix, the stars are supposedly named because they occupy a fixed position in the sky and do not move: this is the opposite of the etymology ἀ- + ἵστημι where the stars were defined through their ever-moving position; with the privative alpha, on the other hand, ἀ- + ἵστημι and ἀ- + στηρίζω are semantically equivalent. That can account for the fact that the same name is given to two types of heavenly bodies, the stars (fixed position, intensive alpha) and the planets (privative alpha). The word καταστερισμός is likewise interpreted as a derivative of στηρίζω with the prefix κατά (see bibl.). The first occurence of the verb is in Iliad refering to the placement (of Iris) in a cloud (11.28) and in the sky (4.443 : οὐράνῳ ἐστήριξε)