The Universe Between 400 B. C. And The Mid-17th Century

Between 400 B.C. and the mid-17th century, questions about the universe arose and revolved around the motion of the planets, location of the Sun and Earth, and the planets’ orbits.

The motion and location of the planets is determined by the planets’ orbits on the same plane and the rate at which they rotate around the sun. They are located on the same plane because all objects in the Solar System were formed at roughly the same time between four and a half to five billion years ago, and were made from the same cloud of gas and dust. Due to planetesimals, small objects that stuck together to form a larger object, colliding with one another, these collisions led to the circular planetary orbits. As the planetesimals grew they began to increase their gravitational attraction, which then led to clumps and rings forming around the sun.

Heliocentric was having the planets revolve around the sun and the geocentric model was having the planets and the Sun revolve around the Earth. During the middle ages the geocentric model was accepted by scientists such as Eudoxus and Ptolemy, as well as the everyday people because it justified that humanity’s home was in the most important place in the universe. However. During the Renaissance new scientific discoveries were made by Galileo Galilei, Nicolaus Copernicus, Tycho Brahe, and Johannes Kepler that argued the universe was based on heliocentrism. Though all scientists contributed valuable study and information to the notion of which model was correct, it was Johannes Kepler that cracked the code about the correct type of model and how Ptolemy was wrong about the motion of the planets. Kepler was able to prove that planets did not complete small circles, epicycles, around the center of the universe, but followed elliptical orbits