That the planets of the solar system revolve around a central star called the Sun was not known for certain. The prevailing theory was that the Earth was the center of the Universe and that the other planets revolved around it. The heliocentric theory , which we will discuss today, is the one in which the Sun is the center of the universe and is a fixed star.
Who developed the heliocentric theory and what is it based on? In this article you will be able to learn about its scientific basis in depth. Would you like to know it in depth? Just keep reading 
Characteristics of the heliocentric theory
During the XNUMXth and XNUMXth centuries there was a scientific revolution that sought to answer all those questions about the Universe. It was a time when learning and discovering new models predominated. The models were created to be able to explain the operation of the planet with respect to the entire Universe.
It is thanks to physics, mathematics, biology, chemistry, and astronomy that we have come to know so much about the Universe. When we talk about astronomy, the scientist who stands out is Nicolaus Copernicus. He was the creator of the heliocentric theory . He developed it based on ongoing observations of the movements of the planets. He used certain characteristics of the previous geocentric theory to refute it.
Copernicus developed a model that explained the workings of the Universe. He proposed that the motion of the planets and stars followed a pattern-like path over a fixed larger star. It is the Sun. To disprove the previous geocentric theory, he used mathematical problems and laid the foundations for a modern astronomy.
It should be noted that Copernicus was not the first scientist to propose a heliocentric model in which the planets revolved around the Sun. However, thanks to its scientific basis and demonstration, it was a novel and timely theory.
A theory that tries to show a change in the perception of such a dimension affects the population. On the one hand, there were times when astronomers talked about solving mathematical problems so as not to leave geocentrism aside. But they could not deny that the model contributed by Copernicus offered a complete and detailed vision of the workings of the Universe.
General principles of the theory
The heliocentric theory is based on some principles to explain all the operation. Those principles are:
- Celestial bodies they do not revolve around a single point.
- The center of the Earth is the center of the lunar sphere (the moon's orbit around the Earth)
- All spheres revolve around the Sun, which is near the center of the universe.
- The distance between the Earth and the Sun is a negligible fraction of the distance from the Earth and the Sun to the stars, so no parallax is observed in the stars.
- The stars are immovable, its apparent daily movement is caused by the daily rotation of the Earth.
- The Earth moves in a sphere around the Sun, causing the Sun's apparent annual migration. The Earth has more than one motion.
- The orbital motion of the Earth around the Sun causes the apparent retreat in the direction of the movements of the planets.
To explain the changes in the appearances of Mercury and Venus, all the orbits of each had to be placed. When one of them is on the side farthest from the Sun in relation to the Earth, it appears smaller. However, they can be seen in full. On the other hand, when they are on the same side of the Sun as the Earth, their size seems larger and their shape becomes a half moon.
This theory perfectly explains the retrograde motion of planets like Mars and Jupiter. It is fully demonstrated that astronomers on Earth do not have a fixed frame of reference. On the contrary, the Earth is in constant motion.
Differences between heliocentric and geocentric theory
This new model was a revolution for science. The previous model, the geocentric one, was based on the idea that the Earth was the center of the Universe and that it was surrounded by the Sun and all the planets. This model was reduced to just two common and obvious types of observations. The first is looking at the stars and the Sun. It's easy to look at the sky and see how, throughout the day, they move across it . This gives the impression that the Earth is stationary and the other celestial bodies are moving.
Secondly, we have the observer's perspective. Not only did the other celestial bodies appear to be moving in the sky, but the Earth itself didn't seem to be moving . They drifted and moved without any sense of motion.
During the 3rd century BC, it was thought that the Earth was flat. However, the fact that our planet was spherical was incorporated into these models of Aristotle. It wasn't until the arrival of the astronomer Claudius Ptolemy that details about the shape of the planets and the Sun were standardized. Ptolemy argued that the Earth was at the center of the Universe and that all the stars were a modest distance from its center.
Copernicus' fear of being imprisoned by the Catholic Church made him withhold his research and not publish it until the moment of his death. It is when he was about to die when he published it in the year 1542.
Explanation of the behavior of the planets
Geocentric theory
Each planet in this system devised by this astronomer is moved by a system of two spheres. One is deferential and the other epicycle. This means that the deferent is a circle whose center point is removed from the Earth. This was used to explain the differences between the length of each season. On the other hand, the epicycle is embedded in the deferent sphere and acts as if it were a kind of wheel within another wheel.
The epicycle is used to explain the retrograde motion of planets in the sky . This can be observed when they gradually decrease their acceleration and move backward before slowly resuming their forward motion.
Although this theory did not explain all the behaviors observed on the planets, it was a discovery that until today has served many scientists as the basis of the study of the Universe.
