Final answer:
Galileo, using an improved telescope of his own design in 1609, was able to observe detailed features of the Moon, as well as other astronomical phenomena like Jupiter's moons and sunspots, that were previously unseen.
Step-by-step explanation:
The individual who made a telescope in 1609 that allowed him to see unprecedented details of the Moon was Galileo Galilei. Although the invention of the telescope itself is credited to Hans Lippershey, Zaccharias Janssen, and Jacob Metius around 1608, Galileo improved upon their designs. With his improved version of the telescope, which he referred to as a spyglass, Galileo was able to make revolutionary observations of the night sky, including detailed views of the Moon's surface, which showed craters and mountains. His work with telescopes led to monumental discoveries, including the moons of Jupiter, the craters and mountains on the Moon, the details of sunspots, and establishing that the Milky Way is composed of a vast number of individual stars. These discoveries significantly altered the contemporary understanding of the universe and solidified the telescope as a fundamental tool for astronomical observations.