Prove that the Earth orbits the sun

Prompted by a letter to the editor in this morning’s Austin American-Statesman, using only equipment or observations easily obtained by an ordinary person on the surface of the planet, how can it be proved that the Earth orbits the sun?

The letter-writer’s hypothesis is that we all live by faith. He knows that the Earth orbits the sun, but since he cannot observe this phenomenon directly, he takes it on faith. Therefore, he has faith in other non-observable things, such as a promised after-life. I think his premise is flawed and that the fact that the Earth orbits the sun can be observed. However, I am struggling to think of how. Any thoughts?

Here’s how io9 suggests proving it, should you ever need to.

Nevertheless, I think the guy made a good point. Many, many scientific facts we take on faith. I’ve become resigned to it. Science has a good track record for improving our lives.

I think a “proof” is hard to do through observations alone.
The idea that the Earth orbits the Sun comes from the difficulty in explaining all of the weird motions observed with respect to other celestial objects- if the Earth is at the center of the universe, how do the planets orbit it? Some of the planets appear to stop and reverse course (retrograde motion). It’s really hard to come up with a system with the Earth at the center that explains that motion.

It is the simplest explanation which agrees with all the observations. That is as close to “Proof” as Science gets.

A quibble.

We largely take it on faith that results are reproducible and take it on faith that other people have indeed done so.

If you tell me there’s a great steakhouse in Perth, Australia, I’ll accept your word on faith. Not a religious sort of faith but the faith that I can verify this opinion directly or that other people can do so and that the balance of probabilities is there’s little reason for you to mislead me about such a thing. Getting to Perth would be difficult to implausible for an “ordinary” person, yet we don’t challenge this sort of “faith”.

Science works more like verifying a steakhouse halfway across the world is any good, not in the sense of a religious belief.

The flaw in the letter is a false equivalence between faith in something ineffable and faith in something we simply choose not (for lack of resources or desire) to personally verify.

People say the same of religious faith. Subjective opinions are subjective.

Really hard, but not impossible; indeed an ancient geocentric model is rather accurate:

Even before Ptolemy, such a gear-based “planetarium” was built.

This is well put. Thanks

You saved me a lot of typing.

What he said.

Me, I have faith in the scientific process. I can construct a chain of knowledge that includes people making hypotheses, people testing hypotheses, competing hypotheses, objective observations to determine which hypothesis is supported by reality. The claims have been independently verified. Not to mention that we actually put robots on Mars, which I’m going to say is pretty much impossible if we misunderstood the solar system to such a ridiculous extent.

The guy having faith in an afterlife does not have anything like this. He has a book written by basically anonymous people thousands of years ago, edited and re-translated who knows how many times, with no actual ability to go to the source of the knowledge. There is no independent verification of the claims, it must be taken entirely on faith.

Ok, sorry, I just can’t seem to stop myself. :slight_smile:

Technically, the earth doesn’t orbit around the sun. The earth and sun orbit around each other. The sun’s effect on the earth is huge (comparatively), but the earth’s effect on the sun is miniscule by comparison. So it “seems” like the earth orbits the sun.

This is one of the ways the Keppler telescope found planets around other stars. One of the ways was the transit method, where the light from a star was decreased slightly as the planet passed in front of it. The OTHER method was looking for slight variations in the star’s position, which implied that the star and a planet were orbiting around each other.


“Prove that the Earth orbits the sun”

It does? :eek:

I believe that an article like that served to inspire the writer to send his letter to the Statesman.

The fact that the inner planets Mercury and Venus exhibit phases and never stray very far from the Sun (from our point of view) is one piece of evidence for a heliocentric solar system. Another would be the occasional retrograde motion of the outer planets, most noticeably Mars.

But that’s just evidence, not proof. Very few things in science are proven in the strictest sense of the word. Most scientific knowledge is provisional.

But I wouldn’t call it faith.

"Faith consists in believing when it is beyond the power of reason to believe." -Voltaire

"Faith: not wanting to know what is true." -Friedrich Nietzsche

Okey dokey. The sun is hot, but it is not evenly hot all over. As the earth goes around the sun, it is exposed in regular order to the hottest side, which we call summer, and the coldest side, which we call winter. Spring and autumn are the transitions.

As for your claims about the Southern Hemisphere having opposite seasons, that is a lot of unprovable nonsense. In Sydney they celebrate Christmas on the very same day we do and you can’t prove otherwise.

As long as you accept the propositions and the movement to the conclusion, you must conclude, in this instance, that the Earth orbits the sun. At 66,000 miles per hour.

Keep in mind that people concluded the Earth went around the Sun long before there was ever a space program. Most of what we know about the universe is based on observations made from here on the ground.

People mentioned phases of Venus and retrograde motion as good lines of evidence, and was good enough for people at Galileo’s time. Another good line of evidence, if you have a big enough telescope, is stellar parallax. Stars will appear to shift slightly in position as the months go by, in direct accordance with the seasons. The simplest explanation is that our point of view of the stars is changing as the Earth itself moves around the Sun.

Not really, no more than the Earth & Moon orbit around each other. To most as long as the center of revolution is inside the other body, it can be said that one orbits the other.

None of this it true.

There’s a lot of nice philosophizing in this thread, and telling me I’m wrong about calling it faith, but I think I’m the only one who addressed the actual question. Given a year, you could pretty well demonstrate the earth orbits the sun. At least, give very convincing evidence that the earth has moved a significant distance.

I guess the post about Venus and Mercury staying close to the sun addresses the question too.

The OP’s question supposes only two possible ways of explaining a phenomenon: 1) Either the explanation for the phenomenon can be easily demonstrated to any layman or 2) we have to blindly accept any explanation that is presented, no matter the source. I think there is some middle ground there.

I can’t prove to any and all that the earth orbits the sun but I have studied physics and math and I’ve looked up at the sky, so I can see that some statements about the way the sun and the Earth interact are much more informed than others and, over time, I’ve come to accept those authorities over guys like the OP’s letter writer. More importantly, if I am moved to get off my lazy ass, I can learn about others who have challenged the ideas that I ‘believe’ and I can see the arguments and the outcomes.

Anyway, there are lots of ways of demonstrating that the Earth orbits the sun, depending on what one means by that. You can learn all about it in college. The fact that they aren’t all simple concepts that are clear to every person on the planet has no relation to their truth or usefulness as a model.

I have faith in the believe, that the light in the fridge turns off when I close the door.

… and the only way to be 100% sure that the light in the fridge is actually turning off, is by checking that it’s off…

Ever sat in a fridge and really, really, really checked?

Faith, right! So, God must be real as well and exciest – it’s the same, right?