Galileo Galilei improved upon the technology of the spyglass, creating a more powerful version that resulted in the first telescope. He also created the first pendulum clock and provided important research that concluded that the planets revolve around the Sun.
Galileo Galilei did not technically invent the telescope, but he made dramatic improvements to the existing spyglass. He experimented with different lenses, which resulted in a much more highly powered spyglass. The improvements allowed him to observe celestial bodies, such as stars and planets. He was also able to discover and observe Jupiter's moons through his telescope, which are known as the Galilean moons.