Notes and Credits: This Document has been adopted from Solar and HeliosphericObservatory (SOHO) Website https://sohowww.nascom.nasa.gov/classroom/activities.html

It is modified in content for use in Phys1411 Introductory Astronomy Class at Tarleton State University by Dr. Goderya

Note: Do not print the whole document. Print only the mapping grid and the associated worksheet. You can collect the data by viewing the images provide here on your computer monitor.

Sunspots and Solar Rotation

Tracking SunspotsUsing real data from SOHO

A classroom exercise for students

You are about ready to start observing and tracking sunspots across the Sun using real images. You can then use this information to determine the rate of the Sun’s rotation.

Some sunspot facts:•Sunspots are dark, cooler areas on the Sun’s surface that indicate areas of strong magnetic activity•They appear dark only because they are not as hot or bright as the area surrounding them (4,000 degrees C. vs. 6,000 degrees C.)•Sunspots extend down into the Sun as well as above where loops of magnetic field lines carry charged particles• They can last from just hours to several months

How BIG are they? Next page…

Sunspots, which usually appear in groups, can grow to many times the size of Earth

Approx. size of Earth

How and when did scientists discover that there were spots on the Sun?

The first telescope was made in Europe in 1608. Galileo, who firstperformed scientific observations in the early 1613, concluded thatthe Sun did indeed have spots. If, as others suggested, these spotsare planets passing in front of the Sun, they’d be the same in the center as near the edges. He noted changes in size and shape. Other scientists came to similar conclusions.

Galileo and one of his original sunspot

drawings

To begin, first print out the mapping grid

How to proceed• Pretending that for each day we are stepping outside

at about the same time each day from June 22 to July 3, projecting the sunspots with the telescope onto paper, and tracing where they appear. Thus, we are observing and recording sunspots.

• For each image from June 22 to July 3 transfer and record the location of each group of sunspots onto the mapping grid on to the same mapping grid.

• Then record the data on Date, Time and Longitude in a table given in the worksheet for each group of spots

• A sample mapping grid is shown.• After completing this task for each group of sunspot

answer the questions in the worksheet.

C

A

June 23

A

C

B

June 24

C

B

A

June 25

C

B

A

June 26

C

B

A

June 27

C

B

A

June 28

C

B

A

June 29

C

B

A

June 30

C

B

A

July 1

C

B

A

July 2

C

B

A

July 3

B

Sample mapping worksheet

Watch the frames be put into motion!There is a movie associated with this PDF file. You will need the QuickTime movie player to watch it. You can download the movie on your PC from the link provided below. https://sohowww.nascom.nasa.gov/classroom/docs/spotexrS.mov

Remember that you can see daily images of sunspots on the SOHO web site at soho.nascom.nasa.gov

For more sunspot information, go to http://cse.ssl.berkeley.edu/segwayed/lessons/sunspots/index.html