(c.1267–1337), Italian painter; full name Giotto di Bondone. He introduced a naturalistic style showing human expression. His name is associated with the legend of “Giotto's O,” in which he is said to have proven his mastery to the Pope by drawing a perfect circle freehand. His works include the frescoes in the Arena Chapel in Padua (1305–08) and the church of Santa Croce in Florence (c.1320).
A European space probe which photographed the nucleus of Halley's comet in March 1986.