What was one of Galileo's contributions to astronomy in the 1600s?

Galileo's contribution to astronomy in the 1600s prominently included his improvement of the telescope. He did not invent the telescope, but he significantly enhanced its design, which allowed for much clearer and magnified observations of celestial bodies. With his version of the telescope, he was able to observe and document the moons of Jupiter, the phases of Venus, and the intricate details of the moon’s surface. This advancement in technology played a pivotal role in shifting the understanding of our solar system and laid foundational work for subsequent astronomers. By creating a more powerful telescope, Galileo opened new avenues for exploration and evidence that countered prevailing astronomical theories of the time.