Interestingly, an Englishman named Thomas Harriot (1560–1621) also observed the Moon with a telescope a few months before Galileo did. Harriot, who is best known today as a mathematician who made advancements in the equations and notations of algebra, made his own telescope and observed Halley’s comet, sunspots, and Jupiter’s moons. Unlike Galileo, however, Harriot did not record or publish much of his work. Galileo did, and also performed follow-up studies of his discoveries. Thus, Galileo is credited with being the discoverer of the Moon’s craters.