c. 1560-1621

English mathematician and astronomer who was among the first to view celestial objects telescopically. He anticipated Galileo's use of the telescope for viewing the Moon's surface (1609) and observing Jupiter's moons (1610), independently discovered sunspots (1611), and made detailed studies of comets. Harriot also made many contributions to algebra including a comprehensive theory of equations and improved notation that includes the signs < for less than and > for greater than.