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Evidence of a Sun-Centered Solar System. According to the Earth-centered model of the universe (Ptolemy 141 AD), the sun orbited the earth outside of the orbit of Venus.
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Evidence of a Sun-Centered Solar System • According to the Earth-centered model of the universe (Ptolemy 141 AD), the sun orbited the earth outside of the orbit of Venus. • Using his telescope, Galileo discovered that Venus has phases just like the moon, including a “full” Venus that appeared significantly smaller in size. • How did this evidence support the Sun-centered model proposed by Nicholas Copernicus? Explain or diagram your answer. Earth-centered model
Venus could not be seen as “full” in the Earth-centered model because the sun would always be behind it. In contrast, the Sun-centered model below shows that Venus can be seen in all phases because it orbits around the sun inside of Earth’s orbit. This also shows why Venus would look smaller in its “full phase”… because it is actually much further away!
Warm-up : Retrograde Motion • Below is a time-lapsed image from NASA that shows the path of Mars as it orbits the sun (counterclockwise). Does Mars really make periodic loops throughout its orbit? How could this image be explained. (Hint: think about Earth’s orbit)
While Mars appears to moving backward, its actual motion is in the same direction as the faster moving earth. This is very similar to what it looks like when passing another car on a racetrack. Called “Retrograde Motion”.
