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I think I have an answer for this question, but I am not a scientist, so I wanted to post my ideas for critique.Here's the premise:http://phys.org/news/2012-08-sun-perfectly-baffles-scientists.htmlSynopsis: Scientists had predicted that the Sun would have significantly more equatorial bulge than it does, and were surprised to find it is a nearly perfect sphere. If the Sun was the size of a beach ball, the equatorial bulge would be about the thickness of a human hair.Here's my simple, straightforward hypothesis to explain: Fusion is what makes the Sun round. While Jupiter and Saturn are compositionally similar to the Sun (mosty hydrogen and helium) and exhibit prominent equatorial bulging, they do not have fusion occuring in their cores. Fusion applies pressure from the center of the Sun outward, and this tends to push the poles out, cancelling most of that flattening. Otherwise, the Sun would have a more pronounced equatorial bulge like Saturn and Jupiter.So, I chalk up the Sun's spherical shape to hydrostatic equilibrium. According to the Internet:"In continuum mechanics, a fluid is said to be in hydrostatic equilibrium or hydrostatic balance when it is at rest, or when the flow velocity at each point is constant over time. This occurs when external forces such as gravity are balanced by a pressure gradient force."I think the same thing applies to plasma in the Sun, which behaves like a fluid in this case.Again, I am not a scientist. I am a layman. Comments welcome.
I have never seen a perfect sphere that gives off solar flares and does not have a smooth surface, the sun is hardly a perfect sphere, it is sphere like because of gravity or magnetic bottling from space?
Quote from: Thebox on 16/09/2015 17:15:15I have never seen a perfect sphere that gives off solar flares and does not have a smooth surface, the sun is hardly a perfect sphere, it is sphere like because of gravity or magnetic bottling from space?First of all, the words "perfect sphere" are not mine. They are from dozens of articles written by scientists and science writers, one of which I posted a link to. I'm using their words.Secondly, they are referring to the overall, mean, average shape of the Sun. Of course, if the Sun was shaped more like an oblate spheroid, it would still have those prominences and flares. That's not what they or I am talking about. If somebody told you a basketball was an example of a nearly perfect sphere, you would not say, "I've never seen a perfect sphere with black grooves circling it, grainy texture, and a hole used to inflate it" unless you were intentionally being obtuse.I think the Sun's nearly perfect spherical shape is primarily a result of hydrostatic equilibrium between the forces of fusion pressure and gravity, with "centrifugal force" barely expressing itself against much stronger fusion pressure.
Plasma is not really a liquid or neither is the sun, so hydro is not really a word involved in any of the suns processes. Do you imagine the sun to be like molten Lava?Either way the sun is not at rest in any sense with viscous outbursts and ''belts'' that flow around it, I think the sun holds its sphere like shape because it is magnetic bottled as can be seen in plasma physics and the attempt to make plasma, is one and the other not the same mimic?technically the sun should just disperse into space as a plasma gas. I think science will argue it is gravity alone and mass that holds the sun together and maintains its shape because gravity is isotropic.
CraigWelcome to the forum.It might be worth getting the full paper as there seem to be suggestions that solar magnetism, turbulence, subsurface and meridional flows might have sufficient effect to explain the lack of bulge.How would you envisage fusion acting. It would still have to overcome any inequalities due to rotational effects.
That's not correct at all. Jupiter has an intense magnetic field, yet it is flattened significantly at the poles. The difference between Jupiter and the Sun is that the Sun is plasma. The Sun is plasma because of fusion. Fusion applies isotropic pressure outward, which cancels equatorial bulge.Gravity still applies to plasma, so no, the Sun should not disperse into space.Science argued that the Sun should be flattened more at the poles, but it is not. That's why the title of the article I posted a link to says scientists were "baffled" by this discovery. That is why I proposed this hypothesis. Something causes the Sun to be a more perfect sphere than Jupiter, and I say that something is isotropic fusion pressure. Imagine a slightly underinflated basketball. Sit on it, and you cause "flattening at the poles." Remain sitting on it, but have someone inflate it the rest of the way. The isotropic pressure cancels the flattening, causing the basketball to be more spherical despite your weight. That's the simplest analogy I can come up with.
Quote from: Thebox on 16/09/2015 19:43:07Plasma is not really a liquid or neither is the sun, so hydro is not really a word involved in any of the suns processes. Do you imagine the sun to be like molten Lava?Either way the sun is not at rest in any sense with viscous outbursts and ''belts'' that flow around it, I think the sun holds its sphere like shape because it is magnetic bottled as can be seen in plasma physics and the attempt to make plasma, is one and the other not the same mimic?technically the sun should just disperse into space as a plasma gas. I think science will argue it is gravity alone and mass that holds the sun together and maintains its shape because gravity is isotropic.That's not correct at all. Jupiter has an intense magnetic field, yet it is flattened significantly at the poles. The difference between Jupiter and the Sun is that the Sun is plasma. The Sun is plasma because of fusion. Fusion applies isotropic pressure outward, which cancels equatorial bulge.Gravity still applies to plasma, so no, the Sun should not disperse into space.Science argued that the Sun should be flattened more at the poles, but it is not. That's why the title of the article I posted a link to says scientists were "baffled" by this discovery. That is why I proposed this hypothesis. Something causes the Sun to be a more perfect sphere than Jupiter, and I say that something is isotropic fusion pressure. Imagine a slightly underinflated basketball. Sit on it, and you cause "flattening at the poles." Remain sitting on it, but have someone inflate it the rest of the way. The isotropic pressure cancels the flattening, causing the basketball to be more spherical despite your weight. That's the simplest analogy I can come up with.
Quote from: Craig W. Thomson on 17/09/2015 14:31:13Quote from: Thebox on 16/09/2015 19:43:07Plasma is not really a liquid or neither is the sun, so hydro is not really a word involved in any of the suns processes. Do you imagine the sun to be like molten Lava?Either way the sun is not at rest in any sense with viscous outbursts and ''belts'' that flow around it, I think the sun holds its sphere like shape because it is magnetic bottled as can be seen in plasma physics and the attempt to make plasma, is one and the other not the same mimic?technically the sun should just disperse into space as a plasma gas. I think science will argue it is gravity alone and mass that holds the sun together and maintains its shape because gravity is isotropic.That's not correct at all. Jupiter has an intense magnetic field, yet it is flattened significantly at the poles. The difference between Jupiter and the Sun is that the Sun is plasma. The Sun is plasma because of fusion. Fusion applies isotropic pressure outward, which cancels equatorial bulge.Gravity still applies to plasma, so no, the Sun should not disperse into space.Science argued that the Sun should be flattened more at the poles, but it is not. That's why the title of the article I posted a link to says scientists were "baffled" by this discovery. That is why I proposed this hypothesis. Something causes the Sun to be a more perfect sphere than Jupiter, and I say that something is isotropic fusion pressure. Imagine a slightly underinflated basketball. Sit on it, and you cause "flattening at the poles." Remain sitting on it, but have someone inflate it the rest of the way. The isotropic pressure cancels the flattening, causing the basketball to be more spherical despite your weight. That's the simplest analogy I can come up with.Two things:1) Plasma (as in the Sun) interacts with magnetic fields, whereas gas (as in Jupiter) does not. The source of the plasma (fusion in the case of the sun, but solar wind in the case of our ionosphere, and gravitational acceleration in the case of accretion discs) doesn't matter.2) An isotropic force plus an anisotropic force must have a net anisotropic effect. Therefore, if we know that an anisotropic force is in effect, there must be another anisotropic force to counterbalance it in order to have an overall isotropic equilibrium.
Quote from: chiralSPO on 18/09/2015 02:07:11Quote from: Craig W. Thomson on 17/09/2015 14:31:13Quote from: Thebox on 16/09/2015 19:43:07Plasma is not really a liquid or neither is the sun, so hydro is not really a word involved in any of the suns processes. Do you imagine the sun to be like molten Lava?Either way the sun is not at rest in any sense with viscous outbursts and ''belts'' that flow around it, I think the sun holds its sphere like shape because it is magnetic bottled as can be seen in plasma physics and the attempt to make plasma, is one and the other not the same mimic?technically the sun should just disperse into space as a plasma gas. I think science will argue it is gravity alone and mass that holds the sun together and maintains its shape because gravity is isotropic.That's not correct at all. Jupiter has an intense magnetic field, yet it is flattened significantly at the poles. The difference between Jupiter and the Sun is that the Sun is plasma. The Sun is plasma because of fusion. Fusion applies isotropic pressure outward, which cancels equatorial bulge.Gravity still applies to plasma, so no, the Sun should not disperse into space.Science argued that the Sun should be flattened more at the poles, but it is not. That's why the title of the article I posted a link to says scientists were "baffled" by this discovery. That is why I proposed this hypothesis. Something causes the Sun to be a more perfect sphere than Jupiter, and I say that something is isotropic fusion pressure. Imagine a slightly underinflated basketball. Sit on it, and you cause "flattening at the poles." Remain sitting on it, but have someone inflate it the rest of the way. The isotropic pressure cancels the flattening, causing the basketball to be more spherical despite your weight. That's the simplest analogy I can come up with.Two things:1) Plasma (as in the Sun) interacts with magnetic fields, whereas gas (as in Jupiter) does not. The source of the plasma (fusion in the case of the sun, but solar wind in the case of our ionosphere, and gravitational acceleration in the case of accretion discs) doesn't matter.2) An isotropic force plus an anisotropic force must have a net anisotropic effect. Therefore, if we know that an anisotropic force is in effect, there must be another anisotropic force to counterbalance it in order to have an overall isotropic equilibrium.I am going to have to read that through again later chiral. It may fit in with something I am looking at.
the only reason your basketball scenario works is because the ball has containment of an outer shell unlike the sun.
Two things:1) Plasma (as in the Sun) interacts with magnetic fields, whereas gas (as in Jupiter) does not. The source of the plasma (fusion in the case of the sun, but solar wind in the case of our ionosphere, and gravitational acceleration in the case of accretion discs) doesn't matter.2) An isotropic force plus an anisotropic force must have a net anisotropic effect. Therefore, if we know that an anisotropic force is in effect, there must be another anisotropic force to counterbalance it in order to have an overall isotropic equilibrium.
Let me try another analogy that's less confusing. A bubble under water is spherical because the outward pressure of the air and the inward pressure of the water create that shape. No container, no basketball skin, just a surface with a spherical shape.
An air pocket under water tries to expand isotropically pushing the water away from the center of the pocket. At the same time the water wants to fill the pocket creating centripetal pressure against an isotropic expansion, if there were no centripetal isotropic pressure of the water (the skin), the bubble would disperse. The water is your skin, space has no observable ''skin'' around the sun, although the isotropic centripetal force of gravity holds the sun together, there is no known ''skin'' to stop the plasma dispersing. The volume of space around the sun is not of the polarity of the sun, there has to be a ''skin'', a virtual confinement .
It's a sphere because that's the shape corresponding to the lowest energy. If there was a bulge in it then there would be non-zero forces which would pull the matter into a sphere making it once again the lowest potential energy.
Let's go back to the basketball
Quote from: Craig W. Thomson on 19/09/2015 19:03:50Let's go back to the basketball Yes lets go back to the basketball which has a hollow core unlike the Sun, spin a snooker ball on any axis at any speed, you will find nothing gives because the core is not hollow. The sun does not bulge because the core is not hollow. nothing gives. simple physics with no complication of fusion.
Any sphere made of matter will distort from spinning, regardless of whether it is solid, glass, liquid, gas, plasma, degenerate matter, or any combination thereof. Unless there is another opposing force...