Aratus, a Greek scientist and poet of the 3rd century B.C.E., offered practical advice for predicting the weather by learning to recognize the seasonal appearances of constellations. Constellations introduced include Andromeda, Orion and Taurus, and others included in the later star catalog of Ptolemy (2d century C.E.). Ptolemy described 48 constellations in the Almagest; currently 88 are officially recognized.