What part did thomas harriott play forming current ideas about astronomy?

Answer 1

Harriott is credited with early works in optics, and made the first illustrations of the Moon as seen through a telescope, some months before Galileo. His observations on sunspots were also the earliest, or perhaps THE earliest, on record. But he published none of his astronomical and scientific work, and his manuscripts were finally cataloged after his death.

http://galileo.rice.edu/sci/harriot.html