In what year did Galileo significantly improve his telescope and begin systematically using it to gather astronomical data?

Answer

1609

After hearing news of a new Dutch invention, Galileo constructed and improved his own telescope in 1609 and subsequently turned it toward the heavens to gather data.

In what year did Galileo significantly improve his telescope and begin systematically using it to gather astronomical data?
Galileoastronomysciencesolar systemheliocentrism