As a space enthusiast, you may be wondering whether our Sun rotates. The short answer is yes, the Sun does rotate.
However, the rotation of the Sun is more complicated than you might think, and much more complex than the Earth’s rotation. This is because firstly, the Sun is a gas and not a solid, and therefore rotates differently.
Also, the length of one full day on our Sun is highly dependent on which individual area of the Sun you’re thinking about. Let’s take a closer look and find out how the rotation of the Sun works.
How Long Does It Take For The Sun To Complete A Rotation?
A certain point on the equator takes around 24.47 days to complete a rotation around our Sun and then return to the same specific point.
Scientists refer to this as the sidereal rotation period, which is distinct from the phase known as the synodic period (the period of time it takes for a certain point on the Sun to rotate back around so that it is facing the Earth).
The Sun’s rate of rotation falls significantly as its poles are approached, meaning that it can take up to 38 days for areas around the poles to complete one full rotation.
What Is Differential Rotation?
We can examine the rotation of the Sun by examining sunspots because every sunspot moves directly across the face of our Sun as part of the normal rotation of the Sun on its axis.
Astronomers have observed solar rotation in great depth, and have discovered that the Sun does not rotate as a whole solid body. Rather, it shows differential rotation; meaning that it spins at a faster rate on the equator in comparison to the poles, where its rotation rate decreases.
This is also true of the gas giant planets, Jupiter and Saturn, who also display differential rotation.
As a result of this differential solar rotation, astronomers choose to measure the Sun’s rotation rate from an arbitrary location of 26° from the equator; which is the approximate position where we see the majority of the sunspots.
From this position, it takes on average 25.38 days to complete a full rotation and return to the same position in space. The Sun doesn’t only vary in its rotation rate according to whether it rotates on its equator or poles; it also differs in rotation speed according to its interior and exterior.
In other words, the interior of the Sun displays differential rotation in contrast with its surface. The Sun’s internal regions; the core and radiative zone rotate simultaneously as a whole solid body.
However, the outer regions; the photosphere and convective zone, display a different rotation speed.
Does The Sun Orbit Our Galaxy?
Both our Sun and the whole solar system orbit around the middle of the barred spiral galaxy we call home – the Milky Way galaxy. The solar system displays an average velocity of around 828,000 km per hr.
This velocity means that it would take an estimated 230 million years to complete one full orbit around the galaxy. Astronomers theorize that the Milky Way galaxy is made up of a central bulge, four major arms, and multiple short arm segments.
Our solar system, including the Sun, is located close to the Orion arm and between two significant arms – Perseus and Sagittarius.
The Sun is around 28,000 light-years from the center of our galaxy and the Milky Way has a diameter of around 100,000 light-years. It is believed that because our galaxy is a barred spiral galaxy – there is a bar of stars crossing the central bulge rather than a bulge of gas and stars.
To Sum Up
Like the other planets in our solar system, the Sun rotates. However, it displays differential rotation speeds – depending on whether it rotates at the equator or poles, and whether we are observing its interior rotation or surface rotation.
This differential rotation means that the Sun can take variable amounts of time to complete a rotation, unlike the Earth. The Sun, like the rest of the solar system, rotates around our barred spiral galaxy, referred to as the Milky Way.
Astronomers observe sunspots when examining the Sun’s rotation, and it’s important to concentrate their efforts on rotation dynamics as this will contribute to furthering our collective knowledge of the universe.
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