The heliocentric theory or heliocentrism is an astronomical theory that states that all planets in our solar system, including Earth, rotate or orbit around a stationary sun. Prior to the theory of heliocentrism it was believed that the sun and other planets rotated around Earth. This would have meant that Earth was the center of the universe. This theory was known as geocentrism and was believed to be true up until the 16th century when technology had advanced enough to provide evidence that supported the Earth and other planets orbiting a central sun.
The first idea of the Earth orbiting a central sun was proposed in the 3rd century by a Greek astronomer named Aristarchus. Aristarchus theorized that the sun was the center of the universe and the known planets orbited this “central fire.” He presented a model that showed the planets in order of their distance from the sun. Using mathematics, he also demonstrated that the sun would be much larger than the Earth itself, making it seem ludicrous that it revolves around a smaller body. However, the technology available at the time made it difficult to prove this theory and many astronomers dismissed his theory.
It wasn’t until the 16th century that a mathematician, astronomer, and Catholic monk named Nicolaus Copernicus was able to give a fully predictive mathematical model of the Heliocentric theory. He was able to support his theory using astronomical observations and astronomical charts and tables. Copernicus was also the first to place the Earth in the third position from the sun and to note that the moon orbits the Earth not the sun. He also showed using his predictive tables that the stars do not obit the Earth, but the Earth in facts rotates showing the stars in different positions. The heliocentric theory is credited to Nicolaus Copernicus and is often called the Copernicus’ model.