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Kepler was a german mathematician and astronomer. After carefully observing the planets, he realized that requiring planetary motions to be exactly circular does not fit the observations perfectly. Kepler tried couple of different paths and found ellipses to fit the best. Kepler formulated three principles known as kepler's laws. The first law states that planetary orbits are ellipses with the sun at one focus. The second law states that the planets move faster when closer to the sun. the third law relates the distance of the planet and sun and how long it takes to go around the sun. Kepler is still thought about today because he proposed Keplers laws and we still use those today.heliocentric

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Galileo made significant improvements to the telescope to view celestial objects. Galileo observed the moons io, europa, callisto, and ganymede orbiting Jupiter. He observed that Venus went through phases like earth's moon. we still think about galileo today because he found the moons of jupiter and his telescope idea helped our telescopes today drastically.heliocentric

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Aristotle thought that the earth was the center of the solar system. He didn’t think the sun was because if we rotated around the sun the stars would move, but the stars are so far away when the planet moves you cant see the stars move with the naked eye. we still think about Aristotle today because he was the first person to get people thinking of our solar system.

Aristotle had a geometric model

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He believed that Ptolemy's model was to complicated. Copernicus believed the heliocentric idea of ristarchus when he developed the first heliocentric model. He believed that every planet orbits the sun is a perfect circle. Copernicus is still thought about today because he made the first detailed model of the solar systemheliocentric

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Ptolemy was a geographer, mathematician, and scientist that lived in Alexandria, Egypt. He made a book in the early 800s that was based off of the observations of the planets. He made a geometric model that scientists use for the next 14 decades. He believed that a celestial body moved at a constant speed in a perfect circle. His models planets are little circles. We still think about ptolemy today because he proposed planet years.geometric

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Aristarchus proposed the heliocentric model of the solar system, but it was not accepted at the time. Aristarchus measured the distance from the sun to the moon. Aristarchus’s model showed the planets way to close. Aristarchus is important today because he proposed the heliocentric model.

heliocentric