<p>Was it when heliocentric model was spreading in the whole world? I saw a model of the solar system that was made in the 18th century where the sun was in the middle and the planets and comets around it and the end it said: &quot;firmament of fixed stars&quot;. Wasn't at that time accepted that stars were suns or atleast not attached to any firmament and fixed?</p>

CC BY-SA 4.0
2023-09-23T06:41:47.857Z
There are some similar questions to this that have already been answered.  There isn't a single answer.  Sometime between 500 BC and Anaxgoras' suggestion that stars are "firey stones" and Bessel's measurement of parallax in 1838.
James K
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2023-09-23T07:28:01.230Z
@JamesK, how does parallax work? Please keep it simple as possible. Not exactly gifted in the brains department.
Hudjefa
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2023-09-23T08:06:04.663Z
@AgentSmith: It’s the angle difference between two points of view. A common example is to look at your finger raised some distance from your eyes, while closing one eye. If you note the apparent position of your finger relatively to distant objects, then close the open eye and open the other one, you’ll notice your finger seems to have “moved” with respect to the background. The principle is the same for stellar parallax, except we use the Earth’s positions six months apart instead of the eyes, and the closer star replaces the finger while more distant stars are the background.
Pierre Paquette
CC BY-SA 4.0
2023-09-23T11:24:25.200Z
@AgentSmith move your head from side to side.  Notice how nearby objects appear to change position relative to distant objects.  You can do the same with stars, only "move your head" is move the earth around the sun. Nearby stars will appear to move relative to distant ones, and by measuring how much they appear to move you can decide how far away they are.
James K
CC BY-SA 4.0
2023-09-23T11:26:09.283Z
see https://astronomy.stackexchange.com/questions/40499/when-was-it-first-determined-that-the-sun-is-a-star or https://astronomy.stackexchange.com/questions/23516/when-did-astronomy-first-discover-that-the-stars-are-bigger-than-the-moon  and https://astronomy.stackexchange.com/questions/36326/how-did-astronomers-deduce-that-the-sun-was-not-a-ball-of-fire Do any of these answer your question?
James K
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2023-09-23T11:33:25.457Z
@JamesK, would I be corrext if I said, closer objects exhibit more parallax than farther objects? Gracias
Hudjefa
CC BY-SA 4.0
2023-09-23T11:37:22.980Z
yes, that is correct
James K
CC BY-SA 4.0
2023-09-25T00:45:07.693Z
Some philosophers were probably convinced of it thousands of years ago and scientific proof came in 1838.
bandybabboon
CC BY-SA 4.0
2023-09-25T06:25:42.440Z
Does this answer your question? [When did astronomy first discover that the stars are bigger than the moon?](https://astronomy.stackexchange.com/questions/23516/when-did-astronomy-first-discover-that-the-stars-are-bigger-than-the-moon)
James K
<star><history>
When did astronomers accept that fixed stars aren't fixed and are at different distances?
Mansur Hasan
# When did astronomers accept that fixed stars aren't fixed and are at different distances?

(Asked by: username_0 on 2023-09-23)

Was it when heliocentric model was spreading in the whole world? I saw a model of the solar system that was made in the 18th century where the sun was in the middle and the planets and comets around it and the end it said: "firmament of fixed stars". Wasn't at that time accepted that stars were suns or atleast not attached to any firmament and fixed?

**Tags:** star, history

> **Comments:**
> **username_1**: There are some similar questions to this that have already been answered.  There isn't a single answer.  Sometime between 500 BC and Anaxgoras' suggestion that stars are "firey stones" and Bessel's measurement of parallax in 1838.  
> **username_2**: @username_1, how does parallax work? Please keep it simple as possible. Not exactly gifted in the brains department.  
> **username_3**: @AgentSmith: It’s the angle difference between two points of view. A common example is to look at your finger raised some distance from your eyes, while closing one eye. If you note the apparent position of your finger relatively to distant objects, then close the open eye and open the other one, you’ll notice your finger seems to have “moved” with respect to the background. The principle is the same for stellar parallax, except we use the Earth’s positions six months apart instead of the eyes, and the closer star replaces the finger while more distant stars are the background.  
> **username_1**: @AgentSmith move your head from side to side.  Notice how nearby objects appear to change position relative to distant objects.  You can do the same with stars, only "move your head" is move the earth around the sun. Nearby stars will appear to move relative to distant ones, and by measuring how much they appear to move you can decide how far away they are.  
> **username_1**: see https://astronomy.stackexchange.com/questions/40499/when-was-it-first-determined-that-the-sun-is-a-star or https://astronomy.stackexchange.com/questions/23516/when-did-astronomy-first-discover-that-the-stars-are-bigger-than-the-moon  and https://astronomy.stackexchange.com/questions/36326/how-did-astronomers-deduce-that-the-sun-was-not-a-ball-of-fire Do any of these answer your question?  
> **username_2**: @username_1, would I be corrext if I said, closer objects exhibit more parallax than farther objects? Gracias  
> **username_1**: yes, that is correct  
> **username_4**: Some philosophers were probably convinced of it thousands of years ago and scientific proof came in 1838.  
> **username_1**: Does this answer your question? [When did astronomy first discover that the stars are bigger than the moon?](https://astronomy.stackexchange.com/questions/23516/when-did-astronomy-first-discover-that-the-stars-are-bigger-than-the-moon)  

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