The sun's permanent position in the sky, plus the fact that Earth and the other planets revolve around it, may give the impression that it is static and does not move or rotate.
Yet we have been aware that the sun rotates since the 17th century. Like the majority of the solar system's planets, this rotation is counter-clockwise, but as well as being significantly slower than Earth's rotation, the sun's rotation is much more complex.
The discovery that the sun rotates dates back to the time of Galileo Galilei, according to The British Library (opens in new tab). Along with several of his contemporary earlier astronomers, Galileo had observed dark spots of the sun that we now call sunspots and understand to be important parts of the solar cycle.
Galileo noticed something else too. He found these dark spots appeared to move, vanishing and returning as he observed the sun with his telescope.
In 1612, the early scientist wrote: "It is also manifest that their rotation is about the sun... to me, it seems more probable that the movement is of the solar globe than of its surroundings," according to the book 'Discoveries and Opinions of Galileo'.
By using sunspots, he had discovered that the sun rotates, pleasingly ironic given these dark cool patches on the surface of the sun are an artifact of that rotation.
To this day, astronomers and solar scientists use sunspots and other features on the surface of our star to measure its rotation. Yet, there is more to learn about the sun's rotation. Primarily, how different it is from the rotation of our planet.
While Earth and the other inner planets are composed of solid rock, the sun is an ultra-hot ball of dense ionized gas — mainly hydrogen and helium — called plasma. That means that the way it rotates is different than the way our planet, Mars, Venus, and Mercury do.
The sun experiences something called differential rotation. This means that its rotation proceeds at different rates depending on where you look at the star.
[...] This type of rotation isn't unique to the sun or even to stellar bodies. The gas giants, Jupiter and Saturn, also experience differential rotation. This is not surprising given their gaseous composition. The ice giants Uranus and Neptune also have differential rotation — all spinning faster at their equators than they do at the poles.
(Score: 0, Funny) by Anonymous Coward on Thursday July 28 2022, @12:56PM (1 child)
n/t
(Score: -1, Disagree) by Anonymous Coward on Thursday July 28 2022, @01:20PM
And with comments like this, SoylentNews is turning into the sesspool that is Slashdot.
(Score: 5, Funny) by inertnet on Thursday July 28 2022, @01:35PM (4 children)
This reads as if it started rotating in 1612. What about those other 5590 years?
(Score: 2) by DannyB on Thursday July 28 2022, @02:20PM (2 children)
Bzzzzzzzzt!
That is only 7201 years. The earth is clearly only 6000 years old.
How often should I have my memory checked? I used to know but...
(Score: 3, Informative) by inertnet on Thursday July 28 2022, @07:43PM (1 child)
1612 was 410 years ago, minus 5590 is 6000 years ago today.
(Score: 1, Insightful) by Anonymous Coward on Thursday July 28 2022, @08:05PM
+1 don't forget the leap seconds.
(Score: 3, Funny) by turgid on Thursday July 28 2022, @09:14PM
God said, "Let there be light." When Galileo started looking a bit more closely He said, "Let it rotate." After Einstein came along he said, "Let there be dice." Subsequently he has said, "Let gravity look funny at cosmological scales." He's always one step ahead of us monkeys.
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 5, Insightful) by ElizabethGreene on Thursday July 28 2022, @02:05PM (2 children)
You should be EXTREMELY suspicious and concerned about any space object that doesn't rotate. Space stuff is condensed from dust and gas by gravity. Things get bigger when particles coalesce by falling into their gravity well, and unless those falling objects have perfect aim their gravitational potential energy is converted into heat and rotation of the condensed object.
A non-rotating object has had its angular momentum stolen by tidal locking, collision, or what/whoever constructed it.
(Score: 5, Informative) by ls671 on Thursday July 28 2022, @03:10PM (1 child)
Every tidal locked object has a rotation. Its rotation period is just equal to its orbit period. Take the Moon as as an example if you wish.
Everything I write is lies, read between the lines.
(Score: -1, Redundant) by Anonymous Coward on Thursday July 28 2022, @10:40PM
> Take the Moon as as an example if you wish.
I took your Mom as an example, as she wished.
(Score: 3, Funny) by DannyB on Thursday July 28 2022, @02:26PM (3 children)
So the rate of rotation of the sun is different if I observe it from Paris instead of New York?
That is contrary to what I would have expected. My expectation would have been that different latitudes of the sun rotate at different speeds. Interesting the new things I learn online every day.
How often should I have my memory checked? I used to know but...
(Score: 3, Insightful) by Ingar on Thursday July 28 2022, @03:05PM (2 children)
The earth is a nice and solid rocky globe. Whether you're on the north pole or the equator, a single rotation always lasts 24hrs.
The sun on the other hand, is a giant blob of hot goo. The goo at the solar equator rotates faster than the goo at the poles.
(Score: 3, Informative) by bzipitidoo on Thursday July 28 2022, @04:40PM
The surface is solid. But Earth's outer core is liquid, and the inner core does experience differential rotation.
(Score: 0) by Anonymous Coward on Thursday July 28 2022, @08:07PM
> The earth is a nice and solid rocky globe.
BZZZT. The earth's radius is 6000km. The solid surface is ~6km. The rest is ???
(Score: 5, Insightful) by progo on Thursday July 28 2022, @02:59PM (3 children)
You're a Northern Hemisphere bigot.
(Score: 2) by ls671 on Thursday July 28 2022, @03:12PM
LOL! I thought the same when I read TFS
Everything I write is lies, read between the lines.
(Score: 2) by captain normal on Thursday July 28 2022, @04:19PM (1 child)
I thought the same thing, from a perspective above the north pole the earth does rotate counter clockwise. From a point above the south pole it rotates clockwise. Kinda makes me wonder about the folks at Space.com.
"It is easier to fool someone than it is to convince them that they have been fooled" Mark Twain
(Score: 1, Funny) by Anonymous Coward on Saturday July 30 2022, @03:16AM
FTFY
(Score: 3, Funny) by maxwell demon on Thursday July 28 2022, @03:47PM
From the it's-rotation-Jim-but-not-as-we-know-it dept.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 1) by rpnx on Thursday July 28 2022, @07:40PM (8 children)
Does the sun rotate is an extremely dumb question. Obviously, the sun does not rotate relative to itself, and rotates from the perspective of objects that have relative motion such that they rotate relative to eachother. Relativity says "moving" and "not moving" are equivalent* and no frame of reference is more correct or privileged than any other. Thus the question of the if the sun rotates is meaningless without a frame of reference. (*inertial frames, at least, but we don't really care about that)
(Score: 3, Informative) by turgid on Thursday July 28 2022, @09:16PM (4 children)
No, that's not what relativity says. A rotating frame is accelerating. Therefore rotation is not like linear motion.
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 1) by rpnx on Friday July 29 2022, @03:53PM (3 children)
Wrong, rotational motion is also relative.
https://www.springer.com/gp/about-springer/media/research-news/all-english-research-news/you-were-right--rotational-motion-is-relative--too--mr-einstein--/10131862 [springer.com]
(Score: 2) by turgid on Friday July 29 2022, @08:25PM (2 children)
Somebody doesn't understand what acceleration is.
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 1, Funny) by Anonymous Coward on Saturday July 30 2022, @03:18AM
Wadaya expect, he gets his information from Jerry Springer. Sheesh.
(Score: 1) by rpnx on Tuesday August 02 2022, @02:04PM
While I am not a physicist, my understanding is that they are equivalent under general relativity because the forces of "acceleration" being felt can be viewed as not centrifugal force but rather the rest of the universe rotating around the object makes the rest of the universe have more energy, which makes it heavier due to mass energy equivalence, which results in an outward pull force felt by the object due to gravity and so on. In the same way that electric forces can become magnetic forces depending on your frame of reference. Every frame of reference will agree in the result, but not the cause.
(Score: 3, Touché) by Anonymous Coward on Thursday July 28 2022, @10:14PM
Wow? Did you get your physics degree from Trump University?
(Score: 1, Informative) by Anonymous Coward on Thursday July 28 2022, @10:37PM (1 child)
Error.
Rotation is a form of acceleration (hints: change in velocity, requires a force). Yes there is a universal frame of reference for acceleration.
(Score: 1, Troll) by rpnx on Friday July 29 2022, @04:05PM
Sorry but you made an error. They are equivalent according to the formulation of general relativity. Also, objects that rotate are just individual particles with straight linear motion being acted upon by forces from other particles in the same object. But that relative motion only exists with regard to a frame that rotates relative to the object. From the perspective of the object which is still, the forces it experiences are due to the rest of the universe rotating around it, not the the object rotating itself.
(Score: 3, Funny) by Betteridge on Thursday July 28 2022, @11:32PM
As usual, I say no.
Er... I mean... yes?
Shit. Who the hell wrote this headline? It doesn't obey the standard laws.