Why is the position of the Sun so fixed?

Question

Please correct me if I tell something wrong.

As we already know, a planet (e.g. Earth) remains on its orbit due to the gravity of the Sun.

If the Sun's gravity were not there, the Earth would be thrown into the space. Now we know, why the Earth stays there.

My question is, what is holding the Sun at its place? Why is the Sun so fixed?

Is there any force that keeps the Sun so fixed?

If you are a passenger in a car driving fast and straight down a smooth highway and there are no lights, you might imagine that the car isn't moving, but it is. What makes you think that the Sun is fixed at all? Relative to what? — uhoh, Jul 10 '20 at 10:22
Thanks for your explanation, very nice exampl! we stick to your example. the first car is our sun, and the second car is (Proxima Centauri), assuming the first car drives around 30km / h, but then the second car has to drive exactly 30km / h, otherwise we will not see each other at some point (we see other solar systems in our galxay always at the same distance), I can not imagine that all stars move at exact speed, and that's why I think so. I hope you understand what i mean. — Eisenbiegler, Jul 10 '20 at 11:01
Okay I think we're getting somewhere... Screen shot: https://i.stack.imgur.com/MlNlI.png Quote: 22.2 km/s. Because of the star's proximity to Earth, Proxima Centauri has been proposed as a flyby destination for interstellar travel. Proxima currently moves toward Earth at a rate of 22.2 km/s. After 26,700 years, when it will come within 3.11 light-years, it will begin to move farther away. — uhoh, Jul 10 '20 at 11:05
Since the straight and smooth highway is so long, we can see cars many kilometers in the distance. Until we get close enough to them to resolve some details, they are just single spots of light, and it is impossible to tell if the distance is constant or is increasing or decreasing. — uhoh, Jul 10 '20 at 11:08
@uhoh, thank you very much, it has become fairly clear to me. ( in short, the sun is not fixed) — Eisenbiegler, Jul 10 '20 at 12:15
@uhoh, I have another question about the sun, could the sun(+ our solar system) one day leave our Galaxy? or is it absolutely impossible ? — Eisenbiegler, Jul 10 '20 at 12:45
yep you are right, that is another question! You can post it as a new question. In Stack Exchange comments are only for clarifying the existing question and answer posts. You can ask as many quality questions as you like, one at a time. — uhoh, Jul 10 '20 at 13:19

score 5 · Accepted Answer · answered Jul 10 '20 at 11:55

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If by "fixed" you mean stationary then the sun is not fixed. It is in orbit around the centre of the Milky Way, travelling at a speed of around $250$ km/s relative to the centre of the Milky Way. At this speed it travels one astronomical unit (the average distance between the earth and the sun) every seven days, and travels one light-year in about $1,190$ years. In other words, its speed relative to the centre of the Milky Way is about $0.1 \%$ of the speed of light.

The sun appears to be fixed relative to the background stars (once you take into account the earth's orbital motion around the Sun) because the stars are very far away, and also because most of the stars visible to the naked eye are also orbiting around the centre of the Milky Way in orbits that are very similar to the sun's orbit.

answered Jul 10 '20 at 11:55

gandalf61

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and because we live our lives in the blink of an eye so to speak – uhoh Jul 10 '20 at 12:19
Thanks for your answer and the explanations. My question is: whether the sun is fixed in our galaxy, I always imagined it like this, the sun has a fixed position in our galaxy and it does not move. – Eisenbiegler Jul 10 '20 at 12:20
Thank you guys, I understood now, as I said, I always thought differently. – Eisenbiegler Jul 10 '20 at 12:22
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@Mr.R Also, our galaxy is moving relative to the other galaxies in our Local Group, and that group is itself moving... – PM 2Ring Jul 10 '20 at 12:32
@PM2Ring, thanks for this info! – Eisenbiegler Jul 10 '20 at 12:35

Why is the position of the Sun so fixed?

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