Eudoxus, about a century earlier, had written two prose works, Φαινόμενα and Ἔνοπτρον, which are both lost; but we are told by the biographers of Aratus, that it was the desire of Antigonus to have them turned into verse, which gave rise to the Φαινόμενα of the latter writer; and it appears from the fragments of them preserved by Hipparchus (Petav. Uranolog. p. 173, &c., ed. Paris. 1630), that Aratus has in fact versified, or closely imitated parts of them both, but especially of the first. The design of the poem is to give an introduction to the knowledge of the constellations, with the rules for their risings and settings; and of the circles of the sphere, amongst which the milky way is reckoned. The positions of the constellations, north of the ecliptic, are described by reference to the principal groups surrounding the north pole (the Bears, the Dragon, and Cepheus), whilst Orion serves as a point of departure for those to the south. The immobility of the earth, and the revolution of the heavens about a fixed axis are maintained; the path of the sun in the zodiac is described; but the planets are introduced merely as bodies having a motion of their own, without any attempt to define their periods; nor is anything said about the moon's orbit. The opening of the poem asserts the dependence of all things upon Zeus, and contains the passage τοῦ γὰρ καὶ γένος ἐσμέν, quoted by St. Paul (Aratus' fellow-countryman) in his address to the Athenians. (Acts 17.28.) From the general want of precision in the descriptions, it would seem that Aratus was neither a mathematician nor observer (comp. Cic. de Orat. 1.16) or, at any rate, that in this work he did not aim at scientific accuracy. He not only represents the configurations of particular groups incorrectly, but describes some phaenomena which are inconsistent with any one supposition as to the latitude of the spectator, and others which could not coexist at any one epoch. (See the article ARATUS in the ) These errors are partly to be attributed to Eudoxus himself, and partly to the way in which Aratus has used the materials supplied by him. Hipparchus (about a century later), who was a scientific astronomer and observer, has left a commentary upon the Φαινόμενα of Eudoxus and Aratus, occasioned by the discrepancies which he had noticed between his own observations and their descriptions.

The Διοσημεῖα consists of prognostics of the weather from astronomical phaenomena, with an account of its effects upon animals. It appears to be an imitation of Hesiod, and to have been imitated by Virgil in some parts of the Georgics. The materials are said to be taken almost wholly from Aristotle's Meteorologica, from the work of Theophrastus, "De Signis Ventorum," and from Hesiod. (Buhle, vol. ii. p. 471.) Nothing is said in either poem about Astrology in the proper sense of the word.

The style of these two poems is distinguished by the elegance and accuracy resulting from a study of ancient models; but it wants originality and poetic elevation; and variety of matter is excluded by the nature of the subjects. (See Quint. Inst. 10.1.) That they became very popular both in the Grecian and Roman world (comp. Ov. Am. 1.15. 16) is proved by the number of commentaries and Latin translations. The Introduction to the Φαινόμενα by Achilles Tatius, the Commentary of Hipparchus in three books, and another attributed by Petavius to Achilles Tatius, are printed in the Uranologium, with a list of other Commentators (p. 267), which includes the names of Aristarchus, Geminus, and Eratosthenes. Parts of three poetical Latin translations are preserved. One written by Cicero when very young (Cic. de Nat. Deor. 2.41), one by Caesar Germanicus, the grandson of Augustus, and one by Festus Avienus.