What kind of scientific observations did Galileo make that challenged Aristotelian cosmology?

• A. Observations of gravity experiments
• B. Observations of comets as atmospheric phenomena
• C. Telescopic observations such as moons of Jupiter and phases of Venus
• D. Observation of sunspots only

Answer: (C)

The main idea here is that Galileo’s telescope revealed that the heavens are not the perfectly ordered, Earth-centered realm Aristotle described. By seeing moons orbiting Jupiter, Galileo showed that bodies in the sky can revolve around something other than Earth. And by observing the full range of Venus’s phases, he demonstrated that Venus must orbit the Sun, not the Earth. Together, these observations undermine the idea that all celestial motion is centered on Earth and that the heavens are unchanging.

The other options don’t challenge that Earth-centered view as directly. Gravity experiments come from terrestrial physics and aren’t the telescope-based demonstration that the heavens operate differently. Interpreting comets as atmospheric phenomena reflects older beliefs but doesn’t show celestial bodies orbiting something other than Earth. Sunspots reveal that the Sun isn’t a perfect, unchanging sphere, but they don’t provide as strong a counterexample to the geocentric model as the planetary observations do.