MÆSTLIN, MICHAEL, in Latin Mæstlinus, a celebrated astronomer of Germany, was born in the duchy of Wittenberg, but spent his youth in Italy. He made a speech in favour of Copernicus's system, which is supposed to have brought over Galileo from Aristotle and Ptolemy, to whom he had been hitherto entirely devoted. He afterwards returned to Germany, and became professor of mathematics at Tübingen, where, amongst his scholars, he taught Kepler, who has praised several of his ingenious inventions in his Astronomia Optica. Though Tycho Brahe did not assent to Mæstlin's opinion, yet he allowed him to be an extraordinary person, and deeply skilled in the science of astronomy. Mæstlin published many mathematical and astronomical works, and died in 1590.