Is the Sun Actually Orbiting the Earth?

In summary, the conventional way of viewing the solar system is that all the planets orbit the sun. However, it is possible to view it from a different perspective, such as holding the Earth at rest and declaring the sun to be orbiting around it. The reason we stick to the conventional view is due to the high symmetry and predictability of circular orbits. Additionally, it is possible to detect acceleration without using another frame as a reference, but not constant velocity. Experiments can be conducted to measure the effects of acceleration, such as the tide on Earth.
  • #1
Smurf
442
3
Now, the conventional way of viewing the solar system is that all the planets orbit the sun, but since you can declare anything at rest in space, can't you just as easily say that the sun is orbiting the earth, since it will appear that way if you hold the Earth at rest?
 
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  • #2
Smurf said:
Now, the conventional way of viewing the solar system is that all the planets orbit the sun, but since you can declare anything at rest in space, can't you just as easily say that the sun is orbiting the earth, since it will appear that way if you hold the Earth at rest?

Hint: you can detect when you're accelerating without having to use another frame as a reference, but you cannot detect that you are either stationary or moving with a constant velocity without using another frame as a reference. Now look again at the scenario you have just described and see if you can find the answer here.

Zz.
 
  • #3
My first thought is wether "acceleration" is the same as a change in velocity. But I'm not sure if circular motion counts as a change in velocity.
 
  • #4
Smurf said:
My first thought is wether "acceleration" is the same as a change in velocity. But I'm not sure if circular motion counts as a change in velocity.

Why not? A "velocity" is a vector. If it changes direction even if it maintains its speed, that is a change in velocity.

Furthermore, things just don't change direction on its own. Remember Newton's First Law. A circular motion requires the presence of a central FORCE. And when you have a net force acting on a body, that body undergoes an acceleration. An "acceleration" is, by definition, a rate of CHANGE of velocity.

Things a very consistent here.

Zz.
 
  • #5
Smurf - someone let you out of GD?

I think you have spent way to much time there based on your OP. :biggrin:
 
  • #6
Astronuc said:
Smurf - someone let you out of GD?
I think you have spent way to much time there based on your OP. :biggrin:
Hey! I have over 2000 posts, and you don't get posts in GD!

I do read the other forums (well, the math ones at least).. I just never have something constructive to add so I don't post there. Isn't that obvious? Look how elementary my physics understanding is!

Look, the reason I'm inquiring about this is because I'm doing an essay competition where we write a logical defence of a known false hood, this is one of the ideas I'm researching to decide what to do.:biggrin:
 
  • #7
Smurf said:
Now, the conventional way of viewing the solar system is that all the planets orbit the sun, but since you can declare anything at rest in space, can't you just as easily say that the sun is orbiting the earth, since it will appear that way if you hold the Earth at rest?

I think the reason we look at it from such a view is because there is high symmetry in the motion of the planets if we do so. If we take the Earth as the reference coordinate system, you will find the planets move in some very complex motion paths instead of circular (elliptical) orbits which are highly predictable and thus useful. As usual, the laws of physics would hold in any coordinate frame you choose. Try solving more problems in mechanics, and you'll see... why would you choose a coordinate system that makes solving your problems difficult? :P

ZapperZ said:
Hint: you can detect when you're accelerating without having to use another frame as a reference, but you cannot detect that you are either stationary or moving with a constant velocity without using another frame as a reference.
I've heard about this many times. Now I'm just wondering. If I were on a rocket free falling towards Earth from a billion miles away, what kind of experiment could I do to tell me that I was in fact accelerating towards Earth and not just floating in space.
 
  • #8
ZapperZ said:
Why not? A "velocity" is a vector. If it changes direction even if it maintains its speed, that is a change in velocity.
Sweet. I was right. :approve:
 
  • #9
mezarashi said:
I've heard about this many times. Now I'm just wondering. If I were on a rocket free falling towards Earth from a billion miles away, what kind of experiment could I do to tell me that I was in fact accelerating towards Earth and not just floating in space.
When you accelerate you experience G's... i think.

Can that be right? Do we experience G's on Earth because we're accelerating around the sun? Maybe we're just used to it we don't notice, how would one conduct an experiment to figure that out?
 
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  • #10
Smurf said:
When you accelerate you experience G's... i think.
Can that be right? Do we experience G's on Earth because we're accelerating around the sun? Maybe we're just used to it we don't notice, how would one conduct an experiment to figure that out?

Sure we do. I don't think that we're so used to it that we don't notice it, it is more that the force acting on a person is so much smaller than the force due to the Earth's mass that we don't notice it. You could calculate the force straightforwardly and if there's a sensitive enough technique you could measure it. The only thing would be that you would need to take so many other things into consideration.
 
  • #11
Smurf said:
When you accelerate you experience G's... i think.
Can that be right? Do we experience G's on Earth because we're accelerating around the sun? Maybe we're just used to it we don't notice, how would one conduct an experiment to figure that out?

Normally, we don't feel gravity when we're in free fall. However, the affect of that acceleration can be "felt" if you're large enough, like the entire planet, because there is a differential in the rate of falling or acceleration. It is called ... <drum roll> ... the Tide! :)
 
  • #12
Tide said:
Normally, we don't feel gravity when we're in free fall. However, the affect of that acceleration can be "felt" if you're large enough, like the entire planet, because there is a differential in the rate of falling or acceleration. It is called ... <drum roll> ... the Tide! :)

Aha! That certainly would be a good way to detect acceleration due to gravity... given you have sensitive enough equipment =D
 

1. Is it true that the sun orbits the earth?

No, it is not true. In reality, the earth and other planets in our solar system orbit the sun. This is known as the heliocentric model.

2. Why did people believe that the sun orbits the earth?

This belief, known as the geocentric model, was prevalent for centuries due to lack of scientific evidence and the influence of religious and philosophical beliefs.

3. What evidence do we have that the sun does not orbit the earth?

There is extensive scientific evidence, including observations made by Galileo and other astronomers, that support the heliocentric model. We also have knowledge about gravity and planetary motion that confirms the sun as the center of our solar system.

4. Do any cultures or religions still believe that the sun orbits the earth?

No, the geocentric model is not widely accepted in modern times. However, there are still some individuals and groups who continue to believe in this theory.

5. How does the misconception that the sun orbits the earth affect our understanding of the universe?

This misconception can hinder scientific progress and understanding of the true nature of our solar system and the universe. It is important to base our beliefs and theories on scientific evidence and continually challenge and update them as new information becomes available.

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