5 ms·

Do you think you could have deduced that stars are distant suns if you'd lived in the ancient world? Apparently the only pre-modern people (i.e. pre-Giordano B

Do you think you could have deduced that stars are distant suns if you'd lived in the ancient world? Apparently the only pre-modern people (i.e. pre-Giordano Bruno) recorded as making the claim were Anaxagoras and Aristarchus of Samos, but their ideas were completely rejected by contemporaries: https://solar-center.stanford.edu/FAQ/Qsunasstar.html https://solar-center.stanford.edu/FAQ/Qsunasstar.html In retrospect, it just seems so blindingly obvious that I'm tempted to believe that I too would have seen through the Aristotelean BS. But surely there must be aspects of reality that will seem similarly obvious to future generations, and yet I don't feel any insights coming on. I should say, Aristarchus is the ideal of maximizing information from minimal data: "Aristarchus of Samos (Samos is a Greek island in the Aegean Sea) lived from about 310 to 230 BC, about 2250 years ago. He measured the size and distance of the Sun and, though his observations were inaccurate, found that the Sun is much larger than the Earth. Aristarchus then suggested that the small Earth orbits around the big Sun rather than the other way around, and he also suspected that stars were nothing but distant suns, but his ideas were rejected and later forgotten, and he, too, was threatened for suggesting such things."

jbaber 3y ago
With the naked eye what similarities are there between the sun and distant stars?
- alan-crowe 3y ago
  One sees signal beacons (a bonfire on a hill, used to send a simple warning message) both up close, and from a distance of many miles. Thus one sees with the naked eye that a great fire looks like a mere candle from far enough away. Then one boldly extrapolates: perhaps it is the same with the sun and the stars.
gpm 3y ago
I definitely wouldn't have reached that conclusion. Evidence in favour: The sun is a light source, they are much dimmer light sources with much smaller radii, consistent with the hypothesis. Evidence against: There are none at intermediate distance, they're either the sun or so far away to practically be a point light [1]. The sun is yellow, they are not [2]. The sun has a partner in size (measured in portion of the sky it takes up) with the moon, which I presumably know is relatively close by, suggesting some form of relation between them [3]. Ultimately I know that there are lots of ways to give off light. Fire, fireflys, lightning, the sun (if it isn't fire), hot metal, sparks from static electricity, ... There just isn't enough evidence to believe that it's more likely that the stars are the same source as the sun than yet another source. [1] As it turns out "so far away to be a point light" is the intermediate distance, but that result requires an amount of empty space that I would find unlikely. I haven't checked this but I suspect a statistical analysis would also find it unlikely. Assuming all stars are the same size as our sun, and that they're distributed uniformly in space. Given that I count the stars and come up with a reasonable minimum and maximum distance bound from their brightness, I suspect it is extremely unlikely that there are as many as there are but none close enough to be noticeably brighter. This result (assuming it is true) is of course the result of the fact that many stars are far larger/brighter than the sun, so we're actually sampling from a much larger volume than my naive estimate suggests. [2] I'm not sure I fully understand this one... the sun appears yellow because of some quirk to do with the light the atmosphere lets in, but why doesn't that make the other stars yellow too? [3] Pure coincidence
- aeneasmackenzie 3y ago
  Re [1] The situation is even worse, when telescopes became available it was discovered that the stars are specifically not point sources. It's just an optical phenomenon, but this was another serious obstacle.
- Cogito 3y ago
  > why doesn't that make the other stars yellow too? Most stars appear white/bluish because they are too dim for our colour receptors to perceive. The spectra arriving at our eyeballs is consistent with what you would expect given the type of star, redshift, and atmospheric conditions, but the perceived colour is not.
furyofantares 3y ago
> In retrospect, it just seems so blindingly obvious Hm, I don't expect many people feel this way!
- allturtles 3y ago
  I've met 21st-century adults to whom it came as a great surprise when I told them the sun was the same kind of thing as the stars.
angiosperm 3y ago
The ancients were misled by apparent size of stars, not realizing they were point sources spread out by atmospheric diffraction. Placed far enough away, they would have to be implausably big by that measurement. So people promoting distant stars had a glaring contradiction they had to ignore. Lesson for modern theorizing.

jbaber 3y ago

With the naked eye what similarities are there between the sun and distant stars?

alan-crowe 3y ago
One sees signal beacons (a bonfire on a hill, used to send a simple warning message) both up close, and from a distance of many miles. Thus one sees with the naked eye that a great fire looks like a mere candle from far enough away. Then one boldly extrapolates: perhaps it is the same with the sun and the stars.

gpm 3y ago

I definitely wouldn't have reached that conclusion. Evidence in favour: The sun is a light source, they are much dimmer light sources with much smaller radii, consistent with the hypothesis. Evidence against: There are none at intermediate distance, they're either the sun or so far away to practically be a point light [1]. The sun is yellow, they are not [2]. The sun has a partner in size (measured in portion of the sky it takes up) with the moon, which I presumably know is relatively close by, suggesting some form of relation between them [3]. Ultimately I know that there are lots of ways to give off light. Fire, fireflys, lightning, the sun (if it isn't fire), hot metal, sparks from static electricity, ... There just isn't enough evidence to believe that it's more likely that the stars are the same source as the sun than yet another source. [1] As it turns out "so far away to be a point light" is the intermediate distance, but that result requires an amount of empty space that I would find unlikely. I haven't checked this but I suspect a statistical analysis would also find it unlikely. Assuming all stars are the same size as our sun, and that they're distributed uniformly in space. Given that I count the stars and come up with a reasonable minimum and maximum distance bound from their brightness, I suspect it is extremely unlikely that there are as many as there are but none close enough to be noticeably brighter. This result (assuming it is true) is of course the result of the fact that many stars are far larger/brighter than the sun, so we're actually sampling from a much larger volume than my naive estimate suggests. [2] I'm not sure I fully understand this one... the sun appears yellow because of some quirk to do with the light the atmosphere lets in, but why doesn't that make the other stars yellow too? [3] Pure coincidence

aeneasmackenzie 3y ago
Re [1] The situation is even worse, when telescopes became available it was discovered that the stars are specifically not point sources. It's just an optical phenomenon, but this was another serious obstacle.
Cogito 3y ago
> why doesn't that make the other stars yellow too? Most stars appear white/bluish because they are too dim for our colour receptors to perceive. The spectra arriving at our eyeballs is consistent with what you would expect given the type of star, redshift, and atmospheric conditions, but the perceived colour is not.

furyofantares 3y ago

> In retrospect, it just seems so blindingly obvious Hm, I don't expect many people feel this way!

allturtles 3y ago
I've met 21st-century adults to whom it came as a great surprise when I told them the sun was the same kind of thing as the stars.

angiosperm 3y ago

The ancients were misled by apparent size of stars, not realizing they were point sources spread out by atmospheric diffraction. Placed far enough away, they would have to be implausably big by that measurement. So people promoting distant stars had a glaring contradiction they had to ignore. Lesson for modern theorizing.