Aratus of Soli was a highly original poet of the early third century BC, famous throughout antiquity for his didactic epic on constellations and weather signs, and imitated by later Greek and Latin poets. Modelled on Hesiod's Works and Days the poem is cleverly updated to appeal to the interests of contemporary Greek readers. This volume presents for the first time in English an edition of the poem with a full introduction, facing translation and a line-by-line commentary. The introduction explains the literary and scientific background, the characteristic features of Aratus's language, style and metre, and the transmission of the text to the end of the Middle Ages. The commentary gives help with the content of the poem and aims to resolve the many problems of text and interpretation. The text is based on a new reading of the manuscripts, including one not used before.