# The Sun Is Not Hot

Discussion in 'Pseudoscience' started by chung, Jun 12, 2013.

1. ### originIn a democracy you deserve the leaders you elect.Valued Senior Member

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It seems Dave explicitly answered your question and yet you say he didn't. So I guess I didn't understand the question either. Are you asking, does the number of revolutions per year of the sun vary or are you asking, does the speed of revolutions on the sun vary with the latitude or are you asking something else?

3. ### billvonValued Senior Member

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Yes. The equator rotates faster than the northern or southern hemispheres. Measuring it is a challenge, because the sun's surface is not solid.

Imagine, for example, if you had to measure the Earth's rotation at the equator. It's easy because we can measure how often (say) Ecuador comes by. But suppose Earth's surface was all water, and there was a 20kt current that circled the equator? Would that meant that the Earth was spinning faster, since the surface was moving faster? And if the current declined, would you say "hey, the Earth isn't spinning as fast any more!" Or would you say "no, it's the crust's speed that is important?"

Same issues with the Sun. The classic way to measure rotational speed is via sunspot speed, which is where they get the average of about 27 days for one rotation. But if you measure something different you'll get a different speed.

5. ### DaveC426913Valued Senior Member

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As far as I can determine, the question he wants answered is: does the rotational period of a given latitude change over time? i.e. does the period of, say 79 degrees North, get shorter and longer.

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Exactly

8. ### Janus58Valued Senior Member

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According to this paper http://pages.astronomy.ua.edu/townsley/ay550-450/solar_rotation_araa.pdf , the rotations at the latitudes vary by a few percent over the course of the Solar cycle. The Solar cycle is caused by the fact that the Sun's magnetic field flips every ~11 years ( the Earth's field flips every 200-300 thousand years.) Since the field is created by a dynamo effect which is driven by convection, and the variations in rotation in latitude is also connected to convection, it doesn't seem odd that there is a feedback between the two.

9. ### river

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When you say " variations in rotation in latitude " what exactly is your meaning ?

10. ### Janus58Valued Senior Member

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The Sun rotates at different speeds at different latitudes, from a period of ~35 days at the poles to ~25 days at the Equator. The small variations in these periods over the Solar cycle do not occur together, but rather propagate from the poles to the equator. So for example, the rotation at the Pole changes first and then the change works it way down the the Equator. The time scale for this propagation is also comparable to that of the Solar cycle.

11. ### river

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So between the equator of the Sun and the north pole of the Sun , there is no variation in rotational speed .

12. ### RainbowSingularityValued Senior Member

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in a round-a-bout way your actually just stating something that is already well known and proven by science.
"hot" as equal to "cold" are but terminology.
how particles act/interact etc.. is called physics.
Physics has no end of highly complex, ... right through to highly educated people explaining in very non complex terms, how these things work.

lots of "radiation" passes through humans... some doesnt.. some will kill you, some will age you.. some are yet to be figured out if & what they do, if anything...

continue studying.
https://en.wikipedia.org/wiki/Particle_physics
https://en.wikipedia.org/wiki/Nuclear_physics
https://en.wikipedia.org/wiki/Quantum_mechanics

13. ### river

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The Hottest part of the Sun, is the Sun's Corona

14. ### Janus58Valued Senior Member

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I just said the exact opposite of that.
1.The rotational speeds change as you move from Equator to Pole
2. There is a small variation in rotation speeds over the time period of the solar cycle.
3. Those variations in rotation do not effect all latitudes simultaneously, so there is also a small variation in the differential between the rotation speeds over time.

15. ### Janus58Valued Senior Member

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Corona temp, a few million degrees.
Core temp, ~ 27 million degrees
So in terms of temperature, the core's is several times larger.

But temperature alone is not the whole story. You also have to consider heat content. The corona is very thin, about 10e-12 times as dense as the photosphere ( the sun's surface), Thus 1 cc of the photosphere contains millions of times more heat than 1cc of the corona does. This is evidenced by the fact that while the corona extends into a volume many times that of the main body of the Sun, it only produces 1/1,000,000 as much light as the photosphere.

RainbowSingularity likes this.
16. ### billvonValued Senior Member

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The exact opposite is true.
Not even close.

17. ### DaveC426913Valued Senior Member

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It is astonishing how you can say this, considering the number of times you have been told otherwise. Are you even reading the answers you're given?

18. ### river

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I realise I'm not explaining my thinking clear enough .

Lets try this from another angle .

So if we start from the north pole of the Sun , down to the edge of the equator , at it's most northern latitude , does the speed of rotation , in this sector of the Sun , vary ?

19. ### DaveC426913Valued Senior Member

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I'm afraid you're getting even less clear.

"...equator, at it's most northern latitude..." makes no sense in there.
The equator does not have a "most Northern latitude". Its latitude is zero degrees at all points.

The answer is - as always - yes. The sun is a ball of roiling gas, and different parts of it rotate at different rates.

20. ### river

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But the equator of the Sun has longitudinal and latitudinal thickness that separates , north and south poles of the Sun .

21. ### Xelasnave.1947Valued Senior Member

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I am not sure what you mean river?
Longitude and latitude are best thought of as imaginary lines... could you please explain what you mean by thickness.
alex

22. ### river

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First longitude and latitude is how we divide the planet into sections , which is used to navigate our oceans and land .

Thickness is using both to define the equator of the Suns limits , north and south extent .

23. ### Xelasnave.1947Valued Senior Member

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How to slice it up you mean?
Still I dont get where you are going with this.
I wish I had bought a solar filter for my scopes as the clouds have gone away and I am dying to photo graph something.
Alex