So many people are aware of the 2 models of the solar system--the geocentric and heliocentric system. Ask anyone which is correct, and they'll say, without any hesitation the heliocentric model. Okay, so far so good, now as *why* the heliocentric model is correct and not the geocentric model and your answer is very likely to be one of 2 things
1)What are you STUPID or something? Of course the planets revolve around the sun.
2)Oh, people used to be very egocentric, they wanted to view themselves as the center of the universe. We're smarter than them.
What do these explanations have in common? They're ad hominem attacks. Rather than trying to resolve the issue of the way the solar system is, they resort to portraying the other side as stupid, inferior, etc. Thank God people like Newton & Copernicus didn't resolve to this, otherwise where would be today? "My idea's right--people who disagree with me are stupid. They don't know anything about science, and are blinded by religion"
So for those of you wishing to *actually* learn why we live in a heliocentric rather than a geocentric universe, keep reading.
The geocentric model places the earth at the center of the universe, with the moon orbiting it, followed by Mercury & Venus, the sun, mars, Jupiter, & Saturn. The constellations too were orbiting the earth according to this model. The rational, as MrHambre pointed out, was pretty simple, you see various celestial bodies moving across the night sky--the ground didn't seem to be moving anywhere. However, there was an odd phenomena to explain. You see, the outer planets wouldn't simply travel in one direction across the night sky--they would sometimes move in the OPPOSITE direction!! Retrograde motion--this was tough to explain, what people assumed was that as the planets orbited the earth, they moved in these mini cycles, epicycles, so from time to time it would seem like they're moving backwards. It was a very complicated system, but mathematically, the geocentric model was alright,not perfect, but alright--people could predict where planets would be in the night sky. But Copernicus came up with, what was at the time, a rather bizarre theory--the sun at the center of the solar system, with the planets, and the earth orbiting it!
So, this other model, the heliocentric view, solved the problem of epicycles very nicely. No longer did we require these little mini orbits. The "retrograde motion" of planets is actually the earth crossing the orbit of a planet (so, modern analogy, you're driving in a car, when you cross a car in the next lane, it **zooms** back even though it's actually moving forward!!). But which is right? People didn't know for a while whether the heliocentric or geocentric model was correct, until Newton came along.
Newton's law of gravitation was simply remarkable. Everyone knew that the gravitational pull of the earth causes an object to fall. I throw an apple, it falls to the ground say a couple of feet away. I then throw the apple from higher up, the apple lands a bit further away. Now, let's think on a bigger scale: I throw this apple, it curves around, and falls toward the earth's surface. If it's far enough from the earth, it'll fall, keep "falling" toward the earth, until it ends up right back where it started (get it?). In effect, it'll be "orbiting" the earth!!! This was Newton's insight. This is what the "mysterious" force is that keeps the planets in orbit around the sun. Indeed, Newton computed the gravitational pull of the earth on the moon, and it worked out. I believe this was done on the other planets as well, but someone else can verify that.
But why is the geocentric model wrong? Why can't we say the earth is the center of the universe? So what if the Sun actually orbits the earth? Well, let's see. The sun is massive (even the ancient Greeks knew this). It's gravitational pull would cause the planets to orbit it instead of the earth! And we don't have a force to keep the sun in orbit around the earth! And we have no explanation in physics for why planets would move in epicycles! Wait a minute...so objects exert a gravitational pull on each other--how come there's something screwy in Saturn's orbit? Uranus was discovered! What's wrong with Uranus's orbit? Neptune was discovered to have a gravitational pull on Uranus! By tracing Neptune's orbit, they discovered something weird--Pluto (so people who didn't know about Pluto's existence weren't stupid or blinded by religion)
THAT'S why the geocentric view is wrong. THAT'S why the heliocentric view should not only be appreciated, but is the correct explanation (If people doubt that the earth rotates, foucault's pendulum can be given as conclusive proof that the earth is not stationary). If such insight can be applied in the evolution-creation debate, that would be great. If people could refrain from ad hominem attacks against creationists, that would be even better.
Regards,
Monsieur Lynx
™ Version 4.2
