Italian astronomer Galileo Galilei was the inventor of the first pendulum clock, after his discovery of isochronism, which is the time that the pendulum takes to swing. Contrary to popular belief, Galileo was not the inventor of the telescope; Galileo built a telescope based on creations by the Dutch, and it was known as a spyglass. Galileo also built a thermometer and a compass during his lifetime.
Many of Galileo's astronomical discoveries occurred because of the telescope that he had built. With the magnification on his homemade telescope, Galileo was able to study the moon as well as other celestial bodies. Galileo's invention started as a telescope with 3x magnification, but he built upon that idea to create a telescope with 30x magnification. Other inventions of Galileo's included a compass, thermometer and several telescopes.
With Galileo's invented telescopes, he was able to see objects, such as Jupiter's satellite moons. These moons are now known as the Galilean satellites, named after Galileo. While Galileo was an inventor, he was more known for his pursuits in other subjects, such as physics, mathematics, astronomy and philosophy. However, because of Galileo's telescope inventions, he put forth the heliocentric, sun-centered view of the universe. Galileo's synopsis was correct, but he was charged with heresy for it.