Sunspot Classification: Teacher's Lesson Plan

Teacher Lesson Plan: Sunspot Classification

For grades 6 - 12

Objectives:

The student will learn basic vocabulary necessary to classify sunspots visually.
The student will discuss the importance of classification schemes.
The student will distinguish between sunspot umbrae and penumbrae.
The student will measure the length of sunspots and sunspot groups.
The student will compare the size of the Earth to the size of a few sunspot examples.
The student will classify sunspots using a modified Zürich classification scheme.

Materials:

Student Sunspot Class handout

Procedure:

Copy and distribute the Student Sunspot Class handout.
After students have read through the activity, ask for examples of other classification schemes students have used. Ask students to list some pros and cons to using classification schemes.
Define terms at the top of the student handout.

Umbra -	The dark central area of a sunspot
Penumbra -	The lighter area surrounding the umbra of some sunspots
*Unipolar group -	A single spot or a single compact cluster of spots with the greatest distance between two spots of the cluster not exceeding three heliographic degrees.
*Bipolar group -	Two spots or a cluster of many spots extending roughly east-west with the major axis exceeding a length of three heliographic degrees.

*Source: Solar Geophysical Data, 474 Supplement, Feb 1984, pp. 21-23, US Dept. of Commerce, Boulder CO 80303, USA

Students meaure the sunspots on the handout.
Direct students to complete procedure # 1 on the student handout.

Note: These sunspots range from simple to very complex! There is a correlation between temperature of the spot and darkness of the image. The darker the portion of an image, the cooler the temperature of that portion of the sunspot. Go over student responses.

Have students use the scale provided on each image of procedure # 2 to estimate the size of the sunspot or sunspot group. You may wish to point out to the students that each scale is different. Remind students that they can mark the scales on a separate sheet of paper and then use the scaled paper as a ruler. When students have finished, direct them to draw a circle (to scale) representing the Earth. Go over student responses.
Have students look at the Big Bear solar image in item 4 on the student page. Discuss the Modified Zürich Classification Scheme used in this activity, going over both the table of classifications and figure of examples.
Note: This classification scheme uses visual characteristics of sunspots recorded in white light. It does not take into account the sunspots' magnetic characteristics.

MODIFIED ZÜRICH CLASSIFICATIONS

Class A	Individual spots or groups of spots that: are unipolar have no penumbra
Class B	Spot groups that: are bipolar have no penumbrae
Class C	Spot groups that: are bipolar have spots with umbrae usually on only 1 side of an elongated group
Class D	Spot groups that: are bipolar have spots with umbrae on both sides of an elongated group have group length less than 10° heliographic longitude
Class E	Spot groups that: are bipolar have spots with umbrae on both sides of an elongated group have group length between 10° and 15° heliographic longitude
Class F	Spot groups that: are bipolar have spots with umbrae on both sides of an elongated group have group length greater than 15° heliographic longitude
Class H	Individual spots or spot groups that: are unipolar have penumbrae

images of types of sunspots

Help students compare the Big Bear solar image to the Mees active region map. Have them notice that the longitude and latitude lines get "bunched up" near the edges of the image on the Mees active region map. This is because of foreshortening. The latitude and longitude lines are on a 3 dimensional sphere and are being projected onto a 2 dimensional circle. Help students identify the following sunspots and sunspot groups on the Big Bear image.

8759

8763

8765

8766

8768

Direct students to complete procedures # 5 and # 6 on the student handout.

Notes: Students may have difficulty in estimating the length of the sunspot groups and may need some extra help. If Internet access is not possible for students, print the sunspot images as handouts. You will also need to post or verbally announce the accepted sunspot classifications after students have completed procedure # 5.

Number	Single or Group?	Unipolar or Bipolar?	Penumbra?	Length ( ^o )	Classification
8759	Group*	Bipolar	Yes	5	C
8763	Group	Bipolar	Yes	5	D
8765	Group	Bipolar	Yes	20	F
8766	Group	Bipolar	Yes	13	E
8768	Group	Bipolar	Yes	13	E

*Depending on the resolution of your printer, this may appear to be a single sunspot.

Note: Spots can also be categorized as small, medium, and large. A small sunspot would have a length of 2 to 3 degrees. Classifications A and H would be considered small. A medium sunspot's length would be between 3 and 10 degrees. Sunspots with classifications C and D would fall into the medium category. The length of a large sunspot would be over 10^o. Sunspots having classifications of D and E would be considered large.

Discuss the pros and cons of this particular sunspot classification scheme. Ask students how it might be possible to improve on this scheme.

Note: Taking into account the magnetic characteristics of the sunspots is one of the improvements that scientists use today.

Rationale:

Classification is an important tool that is used in all of the sciences as well as in our everyday tasks. In this activity students are given the opportunity to practice classifying as well as measuring and inferring. They will also discuss limitations of the classification scheme presented and propose changes to it. Students will learn about sunspots while they practice critical thinking skills.