Astronomy Practice Exam 2025 – Complete Preparation Guide

Galileo addressed the third objection regarding stellar parallax by observing the Milky Way as a cluster of stars. This observation contributed to the understanding that what was perceived as a continuous band of light in the night sky was actually a collection of many stars packed closely together, thereby suggesting that stars were not as distant as previously thought.

The concept of stellar parallax, which involves observing the apparent shift of nearby stars against distant backgrounds as Earth orbits the Sun, was challenging to prove with the technology available at Galileo's time. His focus on the Milky Way helped to provide evidence for the existence of numerous stars and indicated that the universe was populated with many celestial bodies, although he did not have the means to measure their distances accurately. By emphasizing the visibility of clusters rather than individual stars, Galileo laid groundwork for future astronomers to explore the significance of stellar parallax in understanding the scale of the universe.