Abstract:

A sunspot is an area seen as a dark spot on the photosphere of the Sun. Sunspots are concentrations of magnetic flux, typically occurring in bipolar clusters or groups. They appear dark because they are cooler than the surrounding photosphere. During this investigation, students will learn to use computer image processing techniques to measure the size of sunspots and analyze various phenomena visible on sun system images. These skills can be used to scale and analyze images of our Sun, the planets, or any other electronic image found on the Internet. For
additional information about sunspots, and how they are classified and counted can be found at the following site:

http://solar-center.stanford.edu/gloss.html#SUNSPOT

Outcome:

During this investigation, students will be following a multi-step procedure to do the following:
• find, download and save an image of the Sun from the Internet
• use a graphic converter program to change the saved image to either a TIFF format
• use image processing software to view and magnify the image
• measure the diameter and area of sunspots.

Suggested Grade Level & Duration:
Grades 5-8; 2 to 3 fifty-minute periods.

Materials Needed:
image processing software
image format converter
saved TIFF images of Sun ( 2 ) on your computer
a printed image, poster or computer image of the Sun
WWW access, a WWW browser, and a computer

Teacher Note:
In order to process images with your newly acquired image processing software you need to have students convert the images from JPG or GIF to TIFF. To do this, you need to download an image format converter program. You can get programs for either the MAC or PC platform by clicking on the highlighted words in the materials list. By clicking on the highlighted words “images” and “Sun” you will go to a web site that will have several images on line from which you can choose one that is appropriate for this activity. After you have downloaded the installer (follow the instructions given), you can convert images by starting the graphic conversion program. Select OPEN from the FILE pull-down menu. Then, you can select SAVE AS from the EDIT pull-down menu and change the file type of any graphic. Remember that you need to use GIF or JPG when viewing a graphic with a WWW browser -- use TIFF when you want to view an image using an image processing program.