Ara'tus（*)/Aratos), author of two Greek astronomical poems. The date of his birth is not known; but it seems that he lived about B. C. 270; it is probable, therefore, that the death of Euclid and the birth of Apollonius Pergaeus happened during his life, and that he was contemporary with Aristarchus of Samos, and Theocritus, who mentions him. (Idyll. vi. and vii.) There are several accounts of his life by anonymous Greek writers: three of them are printed in the 2nd vol. of Buhle's Aratus, and one of the same in the Uranologium of Petavius. Suidas and Eudocia also mention him. From these it appears that he was a native of Soli (afterwards Pompeiopolis) in Cilicia, or (according to one authority) of Tarsus; that he was invited to the court of Antigonus Gonatas, king of Macedonia, where he spent all the latter part of his life; and that his chief pursuits were physic (which is also said to have been his profession), grammar, and philosophy, in which last he was instructed by the Stoic Dionysius Heracleotes.
WorksSeveral poetical works on various subjects, as well as a number of prose epistles, are attributed to Aratus (Buhle, vol. ii. p. 455), but none of them have come down to us, except the two poems mentioned above. These have generally been joined together as if parts of the same work; but they seem to be distinct poems. The first, called Φαινόμενα. consists of 732 verses; the second, Διοσημεῖα (Prognostica), of 422.
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 Penny Cyclopaedia.) 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.
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.