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Ptolemy
Ptolemy created the geocentric model. He thought that other planets orbited the Earth except the sun. He made up a good reason to say that because he said that the planets spun on a circle or shpere called a epicycle. And that moved on a bigger circle or sphere called a deferent. Ptolemy beleved that the Earth wasn't just the center of the solar system but the universe. -
Feb 19, 1473
Nicholas Copernicus
Nicholas Copernicus created the heliocentric model. He spent most of his life building the heliocentric model. He placed the five known planets (Mercury, Venus, Mars, Jupiter, and Saturn) and Earth orbiting the sun in pefect cicles at a constent speed. He also figured out that the moon orbits the Earth, not the sun -
Feb 18, 1564
Galileo Galilei
Galileo was the first person to observe the planetsv from a telescope. With that he discovered the three largest satillites (moons) of Jupiter. He also discovered the phases of Venus . One more thing is that he found out that the sun had dark patches we now call them sunspots. -
Dec 27, 1571
Johannes Kepler
Kepler was the cheif founder of modern day astronomy. He also invented log books that he used for calculating planitary positions. -
Sir Isaac Newton
Sir Isaac Newton tested the law of gravity by dropping a wooden ball and a cannon ball on the ground at the same time from the leaning tower of Piza. He wanted to figure out which would hit the ground first,hey hit the ground at the same time. He also figured out that the planets orbit the sun because the sun's gravity keeps them close to the sun while the planets inertia keeps them rotating and revolving around the sun.
