A Heliocentric Model

BY: Umaama Hussain

Before the 16th century (and a bit afterward) it was believed that the Earth was the center of the universe – a geocentric system of organization where the Sun and all the planets orbited the Earth. This was the central belief, perpetuated by the Catholic church because (obviously) mankind was God’s best, most perfect, and important creation; it was only natural that the universe revolved, literally, around us. Nothing pains humankind more than to admit that perhaps we are not as important as we would like to believe we are.

However, after a dream (ironically thought the be sent by God) Nicholas Copernicus, a Polish scientist came up with the unprecedented idea that it was the Sun that was the center of the solar system – a heliocentric system of organization with all the planets, including the Earth, orbiting around the star. This assertation was quite a dangerous one to be making as the Catholic church, with its rigid hold over society, did not take lightly to anything nor anyone going against their beliefs, and thus, their authority. Knowing this, Copernicus’ claims were only published after his death.

On the other hand, Galileo Galilei, an Italian astronomer of the 16th century, who firmly believed in Copernicus’ heliocentric system, did not remain quite so quiet about his findings as he went about simultaneously proving Copernicus’ system true and defying the authority of the Catholic church. Galileo made four key observations to do exactly this.

Galileo, one of the first few who thought to turn a telescope to the heavens, observed that the planet Venus went through phases just as our Moon did. Yet, if Venus, along with the Sun, orbited the Earth this would not be possible. Only if Venus traveled around the Sun, passing behind and beyond it, could these phases be explained. This was one of the main observations that virtually proved that our universe could not possibly be geocentric, and the one that infuriated the Catholic church the most.

AN IMPERFECT MOON

Another important observation made by Galileo was of the Moon’s rough and mountainous terrain. Previously, it was the main belief that the Earth was the only corrupt and ever-changing body in the universe whilst all other celestial objects were perfectly spherical and smooth (for this was a heavenly shape) The Moon, however, could be seen to have darker spots on its surface – yet this was explained away by its proximity to Earth, and thus its ‘contamination’ by our corrupt planet. Then, Galileo turned his telescope to the Moon and had the audacity to sketch his studies, publish his drawings, and question.

Upon observation, he realized that the dark spots on the moon were changing and shifting like – well, like shadows – which could only be caused by actual physical features present on the Moon’s surface. The celestial body of our Moon had craters and mountains, just like the Earth did, and was clearly no ‘perfect’ heavenly object. This discovery, along with Galileo’s support of the heliocentric model, but the astronomer in even more hot water with the Catholic church.

SUNSPOTS

Yet, Galileo did not stop there. The Church’s claim of the harmonious and uniform heavens was challenged once again with Galileo’s observation of sunspots. According to the Church and its supporters, sunspots were simply undiscovered planets that crossed the Sun’s periphery, preserving the star’s perfection in their eyes. However, Galileo responded that sunspots originate and then later diminish on the solar disk, with an irregular motion, and so could not possibly be planets. They must exist on the surface of the Sun itself – and therefore the Sun too cannot be perfect.

JUPITER'S STARS

Another startling discovery made by Galileo was of Jupiter’s ‘stars’. Galileo observed that the large planet had four objects surrounding it. Only a few days later did he realise that these objects were actually moons that were orbiting Jupiter. Once again, this observation provided evidence that most celestial objects did not revolve around Earth – further disproving the geocentric model of the universe.

Nevertheless, the Church did not take kindly to the astronomer’s sacrilegious claims, and he was put on house arrest until the day he died. Still, all the astounding and revolutionary discoveries of Galileo’s have aided and abetted our understanding of the heliocentric solar system as well as our exploration of the universe, and to this day Galileo remains one of the main historical figures of astronomy.