Before 500 BC, many people believed the Earth was flat. This thought continued into the Greek and Roman era which started at around 500 BC. The reason behind this is that the people could not see further than the horizon. They believed that the end of the horizon was the edge of the earth and you would fall off Earth if you went too far. The same as when a glass is on the edge of a table and it is pushed a little more. At this time, Pythagoras first claimed that the Earth was round. He had observed the moon which he claimed was round. The terminator, which is the line between the lit and the dark side of the moon, is curved. The dark side of the moon is the shadow of the universe and this proved that the Earth was round. This can be shown with a small and a big ball. A lamp is shining on the big ball which creates a curved line on the small ball.
During the Greek and Roman era, people believed the Earth was in the centre of the universe. This model is called the geocentric model. Geo is a prefix which means Earth and centric means at the centre. Also, the people believed that the other planets moved in perfect circles around the Earth. Circles were considered the perfect shape. During the 1700s, a lot was discovered, and new models were created. People believed that the Sun was at the centre of the solar system which was called the Heliocentric model.
One of the astronomers that first claimed that planets evolved around the sun was a Pole called Nicolaus Copernicus (1473-1543). He knew about Ptolemy's model which was the geocentric model. Copernicus studied astronomy at the University of Bologna and did not agree with Ptolemy. Copernicus did extensive research in another way the universe could be structured. By observing the night sky with his naked eye, he constructed the heliocentric model where the Sun is in the centre and the other planets evolve around the Sun. Both astronomers did however have some similarities in their models. Astronomers had noticed that some planets appeared to move in the opposite direction than the other bodies in the universe before returning to prograde motion which is when a body moves in the same direction as the other bodies in the universe. Ptolemy explained this phenomenon by creating epicycles. Epicycles are cycles within cycles which altered the paths of the planets. Copernicus did not change this in his model however, he did conclude that it was only apparent since the Earth was also evolving around the sun instead of being motionless. Copernicus also still believed that the planets evolved in perfect circles around the sun, similar to Ptolemy's theory. Copernicus not only created the heliocentric theory, he also proposed the idea that the rotation of the Earth caused the change of day and night and the idea that the Earth was tilted on an axis which caused the change in seasons.
Another astronomer that contributed to the heliocentric model was Johannes Kepler (1571-1630). Since Galileo Galilei had made his statements about the heliocentric model, other astronomers started to work on it, including Johannes Kepler. By this time, telescopes were invented and this led to more precise and accurate data collection. While working on the heliocentric model with Tycho Brahe, Danish astronomer of the royal court, Kepler discovered 3 laws of planetary motion. The first law describes that the planets do not evolve around the Sun in a circular motion but in an elliptical motion. An object is pulled towards one foci point but at a very high speed. This causes the object to move further away from the first foci point. The second foci point is empty, however at this point, the object has lost speed and is attracted towards the first foci point. This change in speed causes ellipses. The second law states that a line between the centre of the Sun and a planet sweeps equal areas in the same duration of time. It is also called the law of equal areas. When an object is closer to the sun, it moves faster but when it is further away, the speed decreases. The area that has been covered during a certain period of time is constant regardless of the distance removed from the Sun. If there would be a line between the planet and the Sun, triangles would form over a certain period of time. The reason is that the base of the triangle becomes smaller but the distance between the Sun becomes greater. Kepler's last law, the law of harmonies, compares the orbital period and the orbital radius of a planet to other planets. This is given in the form T2/R3. T stands for the amount of seconds it takes for an object to evolve around the Sun. R stands for the radius of an orbit. When having calculated this ratio for each planet in the Solar System, it is clear that it is a constant. Yet, Kepler still did not know what caused the objects to move. Around 100 years after the laws were created, Isaac Newton suggested a force called gravitation which made the objects move. Based on Kepler's laws, he created the formula F=G (M_1 M_2)/r^2 .
Copernicus had published a book when he was lying on his deathbed. His book was called "Des revolutionibus" and described his new theory about the heliocentric universe. This book caused the Copernican revolution, which is the period when more people started believing that the heliocentric universe was true instead of the geocentric universe which was used in churches. Prior to Copernicus' discovery, the church was the main and primary source regarding science. During the Copernican revolution, people started to realise that the church was not always correct. The church did not have any arguments and explanations as thorough as Copernicus had in his book. This led to the fact that the church gradually lost the authority of science and what people believed. The church wanted to regain that authority and in 1616 they banned "Des revolutionibus" for over 200 years.
Copernicus' book and beliefs had led to other scientists doing more research and proving heliocentrism. After Copernicus, Galileo had worked on heliocentrism and found more evidence which was that Jupiter had more moons, similar to Earth. Galileo's discoveries had inspired Kepler to do more work on the universe model as well. When observing, he discovered that the planets move in an elliptical motion around the Sun, he solved retrograde motion and that a planet would always cover the same amount of space when a line would be between the centre of the Sun and the centre of the planet. He only did not know how the planets would move. Isaac Newton proposed the idea of gravity and inertia which would explain why the planets moved.
Another discovery that had a big impact was that Pythagoras claimed the Earth was round and Aristotle claimed the Earth was a sphere. Eras later Columbus proved this by sailing to "a new world". Since people knew the Earth was not flat and they could not fall off, they were less scared to go out on the ocean and discover new land. When they found new land, they were able to trade and imperialise new areas in the world. European countries started to gain more and unique resources. Overtime, this led to new technologies and eventually the industrial revolution in which a lot of new inventions were made. This caused Europe to become very powerful in the world. Also, people became rich enough to be able to afford new clothing from foreign countries and they started eating different kinds of foods such as rice and tea. People also started to have different leisure activities because they did not need to work as much as before. This way, people started seeing themselves as superior to the rest of the world.