What is the difference between a sunspot and an active region

The plus and minus signs show the positive and negative polarities of ARs, respectively. The image is taken from Andrus We analyzed the daily magnetic complexity and latitude data of ARs available in the SRS list, for the period January to December This time interval includes the whole of SC 23 Jan.

As explained in the introduction, the magnetic complexity of an AR might change from one class to another during its lifetime. We analyzed the data by applying the daily magnetic complexity approach, which includes all associated complexity classes in each AR. In this way, we combined the information of both the lifetime and magnetic complexity of ARs in our analyses. We also compared our results with the cyclic variation of the sunspot number.

Figure 2 presents the variation in the daily number of ARs obtained according to this approach. In practice, this means that our statistic will emphasize long-lived ARs more than short-lived ones. Daily number of ARs from January to December Next, we calculated the abundance of each complexity class in the sample by applying our approach from to Table 2 presents the total count and relative abundance of each complexity class in the sample.

The rest of the configurations i. Table 2. Total and relative abundances of each complexity class according to the daily number of ARs from January to December It is worth mentioning that the NSN closely follows the international sunspot number version 2. Yearly numbers of the most common magnetic complexities in comparison with the yearly average values of the NSN gray shaded area. The upper panel Fig. In addition, this class shows a double peak behavior during the maximum phase in both cycles.

The monthly number for each magnetic complexity was computed and the results were compared with the monthly average value of the NSN Fig. All data have been smoothed using a seven-month moving average. Monthly number of ARs in comparison with the monthly average values of the NSN filled gray shaded areas in both panels.

Both classes show a double peak behavior during the maximum phase in SCs 23 and 24; in each cycle, the two peaks are different in height and the second peak is higher. Furthermore, comparison of the two panels in Fig. Figure 5 shows the monthly number of SARs upper panel and CARs lower panel against the monthly average values of the NSN gray shaded areas in both panels from January to December The data have been smoothed by a seven-month running average. The monthly number of SARs in the upper panel displays a very similar trend as the monthly values of the NSN, including a double peak behavior during the maximum phase in both SCs 23 and The lower panel of Fig.

A double peak behavior is seen in the number of CARs during the maximum phase in both SCs 23 and 24, while the second peak is higher than the first one in each cycle.

A comparison of the two panels of Fig. The maximum of SARs was reached in May during cycle 23 and in December during cycle 24, while CARs peaked in November and January during cycle 23 and 24, respectively these maximum values are marked with circles in Fig. Then, we counted the number of SARs and CARs for a period of four years: two years on either side of their maximum values in both cycles. Table 3. The smoothed values seven-months running average are presented in Fig.

These periods are shown with shaded bars in Fig. Moreover, a comparison of the two panels of Fig. We calculated the monthly numbers of SARs and CARs in the northern and southern hemispheres separately in order to study the north-south asymmetry of ARs.

The upper panel of Fig. The number of SARs shows large hemispheric asymmetry in SC the values in the northern hemisphere reach a maximum during the first peak of the NSN, whereas the values in the southern hemisphere peak later, during the second peak of the NSN.

The monthly average values of the NSN are illustrated with the gray shaded areas in both panels. Upper panel : monthly number of SARs in the north and south hemispheres are shown with the solid and dotted lines, respectively.

Lower panel : monthly number of complex ARs in northern hemisphere solid line and southern hemisphere dotted line. In the lower panel of Fig.

Similar to SARs, the CARs number shows an asymmetry during the maximum phase in SC the number of CARs in the northern hemisphere reaches a maximum during the first NSN peak, while in the southern hemisphere the maximum is reached during the second peak.

We conducted an analysis on the latitudinal distribution of all ARs in each hemisphere for both SCs 23 and The latitudinal width of ARs was computed by using monthly values in order to compare it with the monthly number of CARs.

Figure 8 presents the results of this comparison for the northern hemisphere upper panel and the southern hemisphere lower panel. It has electrically charged gases that generate areas of powerful magnetic forces. These areas are called magnetic fields. This motion creates a lot of activity on the Sun's surface, called solar activity.

Other times, things are a bit quieter. The amount of solar activity changes with the stages in the solar cycle. Solar activity can have effects here on Earth, so scientists closely monitor solar activity every day. Sunspots are areas that appear dark on the surface of the Sun. The temperature of a sunspot is still very hot though—around 6, degrees Fahrenheit!

Why are sunspots relatively cool? These magnetic fields are so strong that they keep some of the heat within the Sun from reaching the surface. In this image, you can see an active region on the sun with dark sunspots. Students should be able to answer these questions using the knowledge and skills learned through this activity as well as the first lesson in this sunspots series. Another lesson in which students measure the area of sunspots can be found at the Yohkoh Public Outreach Project site.

The lesson, Using the Computer to Measure Sunspots , has students use image processing software to view and magnify images taken by the Yohkoh satellite. The data includes the date the sunspot was observed and its area. Students can graph this data and determine in what years the largest sunspots were observed.

Graphing the data will also allow students to determine trends in the size of sunspots over time. The data can be found at History's Biggest Sunspots. See the Tool. See the Collection. See the Lesson. Do the ratios indicate a correlation between the two? This will depend on the students' data. However, students should note that looking at so many numbers makes it difficult to ascertain whether or not there is some correlation.

Some students may thus suggest that a visual representation, or graphing, will make any correlations easier to see and determine. How can we graph the data to determine whether or not there is a correlation between sunspot area and active region area?

Students should suggest making line graphs of the X-ray area and the sunspot area. Distribute graph paper to students. Tell students that they should three graphs: Sunspot area vs.

Time Active region area vs. Time X-ray area vs. Sunspot area It is best to have students make these graphs and discuss them in this specific order. Each graph should have these features: Title Clearly labeled axes with units Clearly labeled points Tell students that by making the first two graphs, they will study the change in sunspot area and active region area over time. Students should analyze their graphs. How did active region area change over time in January ? Does comparison of the two time graphs show any noticeable trends?

If the two graphs show a similar overall shape, comparing them may help students discover the correlation themselves. The more the shapes are alike, the closer the correlation graph would be to a straight line.

Remember that the vertical scales of the two time graphs are different, so that a similarity indicates the X-ray and sunspot areas are proportional, not identical. Encourage students to make guesses about what the X-ray vs. Possible reasons include: Different colors were included in the X-ray areas The visible light sunspot areas have far fewer pixels, and so are much more sensitive to small differences: one pixel more or less may be quite significant.

Compare the depth of the X-ray corona, which extends far out into space, with the small, finite thickness of the photosphere where sunspots are located.

The X-ray disturbances seen in the images may have shapes and sizes that vary rapidly, especially near the edge of the solar disk. Pixel size may not be a convenient unit of measurement. Ask students: How do we know if the differences between the points are due to scatter in the data or error on our parts? This is a thought question.

Students should spend time considering how scientists minimize error in measurement. Students should suggest that there were probably inconsistencies in the way different groups measured area. Describe some difficulties you encountered when measuring sunspot and active region areas on the images.

Students will give varying answers depending on the types of difficulties they faced. Students will probably note that delineating the exact area of a sunspot and particularly an active region was difficult with the mouse.

Also, because a pixel is an exact unit with a definite size, it may have been difficult only covering the areas of the sunspots and active regions. Did you find this resource helpful?