How long is the suns rotational period

To test if the students are able to apply the Kinematics concepts of average speed and rotation period after the activity, one can give them another object to work on, such as the planet Jupiter and use the big red spot. The images were taken on the same day at 16h08 and 17h Besides the live in-class discussions, we propose the following alternatives to evaluate how students have understood the scientific methodology behind this inquiry-based activity. The first option presents the advantage of being doable in class and fosters more interaction within student groups.

Paper version: Ideally, students will perform the activity in pairs. Thus, for each pair provide one set of:. Electronic version: This activity can also be performed on computers either by opening daily images of the Sun in the website www. Alternatively, they can also open the. If you want to show an animated movie of the rotation of the Sun based on the dataset you are using, you will need SalsaJ and a computer with beamer see Introduction part in the Description of the activity.

Feel free to choose any other set of images from this website, provided you select enough consecutive days to cover, at least, a solar rotation.

At the end of each subsection, we provided links where teachers can read more about these topics. The composition of the Sun The Sun is a giant gaseous ball composed of mostly hydrogen and helium. The Sun can be divided into 5 layers: the core, the radiative zone, the convective zone, the photosphere, and the atmosphere. In the next layer, the convective zone, energy is transported by convection upward movement of hot matter and downward movement of cold matter, similar to the boiling of a soup.

Since it is the layer from which most of the light comes, we call it the solar surface, although we would not be able to stand on it. Beyond the photosphere, we find the solar atmosphere, which is composed of two other layers: the chromosphere and the corona. The chromosphere is a thin reddish gaseous layer immediately above the surface.

He was one of the first to do this, preceded by Thomas Harriott and Johannes Fabricius. Galileo knew that if he looked directly through the telescope, he could burn his eye. Instead, he projected the image on a screen to make careful drawings. To his great surprise, he saw dark spots on the Sun. He was very intrigued by the nature of these spots, and therefore he observed and sketched them on a daily basis to study them.

The magnetic nature of sunspots The nature of sunspots remained an enigma until , when the astronomer George Ellery Hale detected intense magnetic fields within these dark regions. Using a spectroheliograph he found that a certain property of the light polarisation emitted by the Sun was altered in a way that is specifically caused by magnetic fields. Today, satellites like Solar Dynamics Observatory SDO are equipped with special instruments to detect the location of magnetic fields on the Sun and infer their intensity.

Figure 1 shows two images of the same day, obtained by SDO: a visible-light image of the whole solar disc and a map of the orientation and intensity of the magnetic fields present on the solar disc magnetogram. The intense magnetic fields are responsible for this cooling. Since magnetic fields produce pressure, plasma inside sunspots is forced out to maintain pressure equilibrium between the sunspot gas pressure plus magnetic pressure and the surrounding plasma gas pressure.

Therefore the plasma inside the sunspot is less dense and a little cooler. Sunspots usually clump together in groups and have lifetimes between several days and weeks. Sunspots are dynamic and evolve together with the magnetic field: they appear, change, disappear. The dataset proposed in this activity is chosen close to the solar maximum, in order to display a large number of sunspots.

Sunspots are found in patches like storms on Earth and are usually located in bands in both the northern and southern hemispheres. The bands that sunspots form in, move from mid-latitudes to almost the equator throughout the year sunspot cycle.

Note that individual sunspots do not drift much in latitude since they only exist for a few weeks - just the latitudes where new spots form move towards the equator. The rotation of the Sun As seen from the Earth the Sun rotates about its axis in about 27 days. Differential rotation is caused by convection in stars. The movement of mass is due to steep temperature gradients from the core outwards.

This mass carries a portion of the star's angular momentum, thus redistributing the angular velocity, possibly even far enough for the star to loose angular velocity in stellar winds. Differential rotation depends on temperature differences in adjacent regions. The Sun Solar Interior. However, its equator spins the fastest and takes about 24 days to rotate, while the poles take more than 30 days. The inner parts of the sun also spin faster than the outer layers, according to NASA.

Back in , Galileo Galilei noticed something odd: sunspots moved across the sun's disk over time, confirming the sun's rotation, according to Stanford University's Solar Center.

Because the rotation axis north—south must be perpendicular to the latitude line east—west , the angle between the east—west line of Sun and the east—west line of Earth in the image can be substitute for.

By moving the projection board back and forth the latitude and longitude lines can coincide with each other Figure 2. In early January and early July, the angle is 0 degrees, while the angle in April and October is approximately We then divide degrees by the angle.

The known sidereal period of the Earth revolving is Assuming that the solar sidereal rotation period is and the rendezvous period of the sunspot observation from Earth is , then we have the following formula:. Step 1. Another method is to implant the solar disk coordinate diagram in Photoshop, so that the two are superimposed. Step 2. Identify the moving distance of the sunspots and then convert it to the movable angle angular displacement.

Step 3. Divided by the time, the angular velocity is obtained. Step 4. Step 5. For example, The heliolongitude of sunspot number in is Therefore, the sunspot changed Although the results were not identical, the difference between them was small.

As a result, the solar rotation period can be accurately estimated by these methods. From the observations of sunspots in January, July, and October of , we could find that the rotation period of the sun was about 25 days taking 3 days.

The authors declare that there is no conflict of interests regarding the publication of this paper. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.