Sun rotation difference (equator/latitude/pole)?

• drewterry
In summary, the sun has a differential rotation that applies to other gaseous bodies and also revolves around the galactic center at a speed of 220 km/s. The sun has a polar radius that's larger than its equatorial radius, but it's only 5 miles difference. Time is relative to Earth time and in our solar system.

drewterry

I just learned the sun has an equatorial rotation rate of approximately 25 Earth days, and a polar rotation of approximately 31 days.

Intuitively, by the laws of physics, it should be the other way around: longer at the equator and shorter at the poles?

Also, if our solar system is within a larger orbit, is there a year for the sun in that orbit?

What I read is in terms of our year here on Earth - not that there is anything wrong with the Earth year, of course.

I love the year here on Earth.

Any light cast on my shadow is, in advance, very much appreciated.

I'm sure there are others on this board who can explain to you the exact mechanism in GREAT detail (eg., spacetiger), but I'll just stick with the obvious superficial answers to start off :)

drewterry said:
I just learned the sun has an equatorial rotation rate of approximately 25 Earth days, and a polar rotation of approximately 31 days.

Intuitively, by the laws of physics, it should be the other way around: longer at the equator and shorter at the poles?

You're referring to the sun's "differential rotation" which occurs because the sun is not a big solid ball (it's plasma... super hot ionized gas), different parts rotate at different angular velocities.

This differential rotation applies to other gaseous bodies like the Jovian planets, as well as the disk of the galaxy.

Also, if our solar system is within a larger orbit, is there a year for the sun in that orbit?

If I understand you, you are asking: does the sun itself orbit another body in space?

If that's what you are asking then the answer is YES. Our sun revolves around the galactic center at about 220 km/s, and it takes one "galactic year", or approximately 220 MILLION earth-years, to orbit. Interestingly enough, that's a supermassive BLACK HOLE that the sun is orbiting around!

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Follow-up question on galactic year and shape

RetardedBastard said:
I'm sure there are others on this board who can explain to you the exact mechanism in GREAT detail (eg., spacetiger), but I'll just stick with the obvious superficial answers to start off :)
You're referring to the sun's "differential rotation" which occurs because the sun is not a big solid ball (it's plasma... super hot ionized gas), different parts rotate at different angular velocities.
This differential rotation applies to other gaseous bodies like the Jovian planets, as well as the disk of the galaxy.

What shape is the sun (i.e. shape consistent with the rotation times)?

It should be wider at the poles than at the equator, correct?

RetardedBastard said:
If I understand you, you are asking: does the sun itself orbit another body in space?
Our sun revolves around the galactic center at about 220 km/s, and it takes one "galactic year", or approximately 220 MILLION earth-years, to orbit.
Interestingly enough, that's a supermassive BLACK HOLE that the sun is orbiting around!
Yes, exactly what I wanted to know.

My next question is a follow-up question on the time of "galactic year" = 220 million earth-years.

Is time always relative to time here on Earth and/or in our solar system?

The sun is a plasma ball, as mentioned, it rotates differentially like a fluid.

drewterry said:

What shape is the sun (i.e. shape consistent with the rotation times)?

As Chronos pointed out, the sun is shaped like a ball (a SLIGHTLY flattened ball).

It should be wider at the poles than at the equator, correct?

If you are asking if the sun's "polar radius" is larger than the "equatorial radius", then the answer is NO -- it's actually the other way around. Due to the centrifugal effect of the sun rotating on its axis, the equator is SLIGHTLY bulging out. But this difference between the polar radius and the equatorial radius is VERY VERY small -- only about 5 miles or so [1] (which is insignificant given the radius of the sun -- over 400,000 miles). So, for all intents and purposes, the sun is basically a big ball.

My next question is a follow-up question on the time of "galactic year" = 220 million earth-years.

Is time always relative to time here on Earth and/or in our solar system?

If I understand your question correctly, then YES, time is given in Earth years (or months or days, etc.), unless otherwise stated. So when the author of that link I gave you above says, "at the equator the surface rotates once every 25.4 days; near the poles it's as much as 36 days", he means EARTH days.

Hope that helps!

[1] Godier, S., Rozelot J.-P. (2000) Astronomy and Astrophysics 355: 365–374.

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Suns apparent differential rotation

Hi Drewterry:

I may not be of much help on this but there is common belief amoung astronomers (which I am not) that the Sun exibits differential rotation. This to discribe the observation that the Sun's equator rotates faster than the balance of the Sun as you travel towards the poles.

Just looking at the Sun the surface is quite uniform except for the Sun Spots that show up black. The measurement of the Sun's rotation is usualy dependent on the observation of the Sun spot movement and that observation does fully support the conclusion.

I do not know of any clear cut explanation for why the Sun, or Jupiter for that matter as cited in a earlier reply, would exibit differential rotation. If it was due to the drag of the planets on the Sun it should not be so wide spread because the planets are pretty close to the eliptic. Perhaps the pull of the planets are slowing down the suns rotation so the equatorial area rotates slower. Keep in mind the size of the Sun incomparison to the planets. It appears unlikely the tiny specks could effect the Sun's rotation, but we do not know for sure.

Another possibility, for which there is no proof at all, is that the very large size of the Sun causes the poles to be 432,000 miles farther from the equator when the sunlight we see is sent on its way. That means it will take the sunlight a wee bit longer to catch up with the light from the equator and may cause a visual effect simulating the different visual effects on rotation. One thing that interests me about this is that the degree of differential rotation we see migrates uniformly from the equator to the poles just as the shape of a sphere causes each step of the way to be farther and farther away.

I do not wish to confuse you so recall this last comment has no documentation. It is simply fun to consider other prospects when proof positive is lacking.

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What is the difference in sun rotation between the equator and the poles?

The sun rotates at different speeds at different latitudes due to its spherical shape and the Coriolis effect. At the equator, the sun rotates at a speed of about 1670 kilometers per hour, while at the poles, it rotates at a speed of about 0 kilometers per hour.

Why does the sun rotate at different speeds at different latitudes?

This is due to the Coriolis effect, which is caused by the Earth's rotation. As the Earth rotates, it creates a force that deflects objects moving across its surface, including the sun. This deflection is greater at the equator, resulting in a faster rotation speed, and decreases towards the poles, resulting in a slower rotation speed.

How does the sun's rotation affect the length of a day?

The sun's rotation affects the length of a day by causing it to be longer at the poles and shorter at the equator. This is because the Earth's rotation is synchronized with the sun's rotation, so the slower rotation at the poles results in a longer day, while the faster rotation at the equator results in a shorter day.

Is the sun's rotation constant across all latitudes?

No, the sun's rotation is not constant across all latitudes. As mentioned before, the rotation speed varies from 1670 kilometers per hour at the equator to 0 kilometers per hour at the poles. Additionally, the sun's rotation also varies slightly due to other factors such as solar flares and sunspots.

How does the difference in sun rotation affect the Earth's climate?

The difference in sun rotation affects the Earth's climate by contributing to the formation of atmospheric circulation patterns. These patterns, known as Hadley cells, transfer heat from the equator to the poles, influencing global weather patterns and climate zones. The difference in sun rotation also affects the strength and location of jet streams, which play a crucial role in weather patterns and climate.