The permanent position of the sun in the sky, plus the fact that the Earth and the other planets revolve around it, can give the impression that it is static and does not move or rotate.
However, we have been aware that the sun tour from the 17th century. Like most of the Solar systemOn the planets of , this rotation is counterclockwise, but in addition to being significantly slower than LandThe rotation of the sun, the rotation of the sun is much more complex.
How do we know that the sun rotates?
The discovery that the sun rotates dates back to the time of Galileo Galilei, according to the british library (opens in a new tab). Along with several of his earlier contemporaries astronomersGalileo had observed dark spots on the sun that we now call Sunspots and understand that they are important parts of the solar cycle.
Galileo also noticed something else. He discovered that these dark spots seemed to move, disappearing and coming back as he observed the sun with his telescope.
In 1612, the first scientist wrote: “It is also manifest that its rotation is about the sun…it seems to me more probable that the movement is of the solar globe than of its surroundings”, according to the book ‘Discoveries and opinions of Galileo’ (opens in a new tab)(Doubleday, 1957).
Using sunspots, he had discovered that the sun rotates, which is pleasantly ironic given that these cool, dark patches on the sun’s surface 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. However, there is more to learn about the sun’s rotation. Mainly, how different it is from the rotation of our planet.
Is the rotation of the sun different?
While Earth and the other inner planets are made of solid rock, the sun is an ultra-hot ball of dense ionized gas, mostly hydrogen and helium – called plasma.
That means the way it spins is different than the way our planet, Mars, VenusY Mercury do.
The sun experiences something called differential rotation. This means that its rotation proceeds at different speeds depending on where you look at the star.
“Since the sun is a ball of gas/plasma, it doesn’t have to rotate rigidly like solid planets and moons do.” according to (opens in a new tab) POT. “The source of this ‘differential rotation’ is an area of current research in solar astronomy.”
Moving from the sun’s poles to its equator, the time that this area of plasma rotates shortens. The poles complete a rotation in 35 days, while the area just above the equator completes a rotation in just 25 days. This means that no area of the sun completes an orbit as fast as our planet does.
However, the differences in our star’s rotation rates are not isolated from its surface. The inner layers of the sun also rotate at different speeds, and the inner regions actually rotate more like the solid bodies of the inner solar system.
Astronomers estimate that the sun’s core actually rotates as fast as once a week, four times faster than its surface and layers in between, according to NASA. Solar and Heliospheric Observatory (SOHO) page (opens in a new tab). This has led solar scientists to intensively study the effects that arise as a result of the different rates of rotation across our star.
This type of rotation is not exclusive to the sun or to stellar bodies. gas giants, Jupiter Y Saturn, also experiences differential rotation. This is not surprising given its gaseous composition. the ice giants Uranus Y Neptune they also have differential rotation: they all spin faster at their equators than at their poles.
Why does the sun rotate?
The counterclockwise rotation of the sun and the counterclockwise rotation of the entire solar system (except for two planets) is the result of their formation about 4.5 billion years ago.
At this point in the universeIn history, the solar system was nothing more than a giant spinning disk of gas and dust. NASA science suggests (opens in a new tab) that an exploding star caused it to collapse into a solar nebula.
In the center of this nebula, our formed by the sun incorporating 99 percent of the available matter with the outer dust clumps that form the planets. But, it also incorporated something else.
“The rotation of the sun is due to the conservation of angular momentum”, scientist at the National Radio Astronomy Observatory (NRAO) jeff mangum said (opens in a new tab). “What this means is that the gas cloud from which the sun formed had residual angular momentum passed onto the sun when it formed, giving the sun the rotation we observe today.”
Additional Resources
Find out how NASA and ESA are investigating the core of the sun, including how fast it spins at NASA SOHO Page (opens in a new tab). Also, you can learn more about Venus and Uranus, which break the rules of the solar system, and their retrograde rotation in the Science alert website (opens in a new tab).
Bibliography
“Galileo’s sunspot letters (opens in a new tab)“. The British Library (2022).
“Solar rotation varies according to latitude (opens in a new tab)“. NASA (2013).
“Discoveries and Opinions of Galileo (opens in a new tab)(Doubleday, 1957).
“ESA and NASA’s SOHO reveal a rapidly rotating solar core (opens in a new tab)“. NASA (2017).
“Our Solar System”. nasa Science, Solar System Exploration (opens in a new tab) (2021).
“Why does the sun rotate?” National Radio Astronomy Observatory (opens in a new tab) (2020).