Galileo Galilei made an educated guess (and was later on proven to be correct) that the Sun is in the middle of our Solar System.
The sun has rings (I think)
As proposed by the Heliocentric Theory, the Sun is the center of the Solar System.
People thought the earth was in the center of the solar system
That it wasn't the earth that was the center of the solar system but the sun. He tried to explain his theory to the catholic churches but they didn't want to hear it for they didn't like his theory. This caused a contradiction and Galileo was sent to house arrest. He had to publicly say that he was wrong. But Galileo knew he was right and until the day he died he never had a doubt. It was much later that he was proven right.
Galileo discovered Jupiter's Moons. After them for a while, he realized that they orbited around the planet. He took a look at Mars and Venus and realized that they orbited around the Sun. This let him think that the Earth was orbiting the sun as well. His theory here, however, argued against Ptolemic's model thinking that the Earth was the center.
Galileo's ideas are important to science because after all that he said, every scientist and philosopher stared to think of new ideas. One of Galileo's ideas was the theory of heliocentic (meaning the sun was in the center of the solar system). Before Galileo's theory, every scientist and philosopher believed in Geocentric (meaning the Earth was the center of the solar sytem).
Nicolaus Copernicus proposed that the Sun, not the Earth, was the center of the solar system and that the planets, including Earth, revolved around the Sun in circular orbits. This heliocentric model challenged the prevailing geocentric view of the time.
Aristotle first thought that the Earth was the center of the solar system. Ptolemy was the second one to think of the theory.
The solar system formed from a rotating cloud of gas and dust called the solar nebula about 4.6 billion years ago. Gravity caused this cloud to collapse and form the sun at its center, with the remaining material forming the planets, moons, asteroids, and other objects in the solar system.
Ask not what Ptolemy thinks of his solar system, but what his solar system thinks of Ptolemy.
The sun has the majority of the mass in the solar system. Gravitational attraction varies directly as the magnitude of the mass. The sun therefore has the greatest gravitational effect in the solar system.
Think about it, the solar system isn't that big. But I think there are microbes and bacteriums on one of the planets.