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The Sun-centered or heliocentric model of the solar system is called the Copernican model (after Copernicus) and more closely matches the modern astronomical notions. By contrast, the geocentric or Earth-centric model is often called the Ptolemaic.
Although there were several thinkers which proposed something like the heliocentric model before him, Copernicus is identified most with the idea; and it took his name, the Copernican system, contrasting with the geocentric model that identified Earth as the center, known as the Ptolemaic model.
Galileo did not have his own theory. He was a supporter of Copernicus's heliocentric theory and an opponent of the geocentric Ptolemaic theory. Eventually both theories were rejected in favour of Kepler's theory. But Kepler's theory uses the heliocentric idea from Copernicus's theory.
Ptomely thought that the earth was at the centre of the universe and everything revolved around it. His model had everything moving in perfect circles or circles within circles. Copernicus suggested that the Earth in fact revolved around the sun. It wasn't until Galileo and the invention of the telescope that Copernicus was proved right Later Kepler went on to prove that the planets orbit in elliptical and not circular orbits.
When Galileo observed that the planet Jupiter has moons which are in orbit around the planet, this made it more believable that planets orbit the sun, since it was already established that not everything orbits the Earth, as had previously been believed in the Ptolemaic system.
Copernicus.
Copernicus.
Copernicus
He placed the Sun in the middle of the Solar System, instead of the original format where the Sun, Earth, and moon were all in the middle.
He placed the Sun in the middle of the Solar System, instead of the original format where the Sun, Earth, and moon were all in the middle.
The main idea in the Ptolemaic system was that the Earth was at the center of the universe, with the Moon, Sun, planets, and stars orbiting around it in perfect circles. This geocentric model dominated Western astronomy until it was eventually replaced by the heliocentric model proposed by Copernicus.
He placed the Sun in the middle of the Solar System, instead of the original format where the Sun, Earth, and moon were all in the middle.
Copernicus published an alternative model of the planets' movement in 1543 that had the Sun at the centre. It was the first heliocentric model. It used orbits based on combinations of circles, as the ancient Ptolemaic system had done, which was geocentric. In Copernicus's model the paths followed by the planets were less complicated, but other than that Copernicus had no way of proving if it was right or not at that time, so it isn't known whether he believed in it.
Copernicus used perfect circles for the orbits of the planets.
The Sun-centered or heliocentric model of the solar system is called the Copernican model (after Copernicus) and more closely matches the modern astronomical notions. By contrast, the geocentric or Earth-centric model is often called the Ptolemaic.
Brahe's theories revolved around the ptolemaic system, where Earth was the centre of the Universe. Copernicus stated that the Earth is not the center of the Universe, but we revolve around other masses as well.
Nicolaus Copernicus was the first to establish the theory that the Sun, and not the Earth, was the center of the solar system. This heliocentric theory changed the former one set in 150 AD by Ptolemy. It had a huge impact, forcing the Catholic Church, mired in Ptolemaic thought and timekeeping, to admit wrong and institute change.