Features of the Sun

Engage students with images of the Sun.

• Have students view a photo of the Sun that is mostly "bland" and featureless (like this Photo of the Sun without Sunspots). Ask them whether they think the Sun always looks so plain. If they answer "no", ask them to describe the sorts of features they expect to see on images of the Sun. If they answer "yes" then show a Photo of the Sun with Sunspots and have students compare the two photos.
  • PDF of the Photo of the Sun Without Sunspots (for download and/or printing)
• If your students are familiar with the electromagnetic (EM) spectrum, tell them that this image was taken with light from a specific wavelength in the red part of the visible light spectrum (then colored with a yellow-orange tint). Ask them whether (and how) they think the appearance of the Sun is different in other wavelengths of light and in images showing other parts of the EM spectrum, such as infrared or ultraviolet "light".

Explore by describing features seen on photos of the Sun.

• Have students write descriptions of the features they see in each image listed below. At this point, students generally won't know what the features are, so their observations will be purely descriptive, not explanatory. For example:
  • "I see several dark spots near the left edge of the Sun in this photo."
  • "There is a fuzzy glow around the Sun in this image."
  • "There are some bright areas in the lower right and several squiggly dark lines scattered around this picture."
• Optionally, you can divide students into groups and have each group examine and describe a subset of the entire list of images; then share summaries of their observations with the rest of the class. This approach will shorten the duration of this activity and provide students with opportunities to collaborate and communicate.
• Images to explore:
  • PDF with all images  (to download and print)
• Individual images on the web:
  • Visible (Red) Light View of the Sun – March 29, 2001
  • Ultraviolet View of the Sun – September 19, 2010
  • Ultraviolet View of the Sun – September 14, 1999
  • Ultraviolet View of the Sun – November 4, 2003
  • Solar Eclipses – November 3, 1994 and February 16, 1980
  • Solar Eclipse – August 11, 1999
  • Visible (Red H-alpha) Light View of the Sun – July 18, 2000
  • Ultraviolet View of the Sun – April 21, 2012
• An answer key illustrating the features that students should notice is provided in the Explain section below.

Explain by identifying features on Sun photos with the help of background reading.

• Have students read about various features and "parts" of the Sun, referencing the web pages below. You may wish to divide the readings among different groups of students and have groups explain the feature of the Sun they explored. This reading strategy guide might help your students focus on key points in these readings.
  • "Parts" of the Sun: This is background information that helps provide context for the explanations of features (below). You can have students skim these pages, or even skip these readings altogether, if you are pressed for time.
    • The Sun's Atmosphere - including the solar corona (upper atmosphere) and chromosphere (lower atmosphere)
    • Photosphere - the visible "surface" of the Sun
    • The Sun's interior - core, radiative zone and convective zone
  • Solar Features and Events
    • Sunspots
    • Solar Prominences
    • Solar Filaments
    • Coronal Loops
    • Active Regions
    • Coronal Holes
    • Solar Flares
    • Coronal Mass Ejections (CME)
• After they have learned about solar features, ask students to look over the images (listed in the Explore section above) a second time. Have them describe (in writing) the features they see in the images using the terminology they just learned by reading about the features.  If you are divvying the readings among groups of students, you may wish to have student groups serve as experts on their topics during a whole-class discussion of the images, with student "experts" chiming in on the features they learned.

Extend student learning through a web scavenger hunt.

• Have students look up more images of the Sun on the web and identify and describe the features they see in those images. This could take the form of a scavenger hunt: have students find one or more example of each of the features in the "Solar Features and Events" list in the "Explain" section above (sunspots, solar prominences, coronal loops, etc.).
• Here are a few web sites with great images of the Sun:
  • NASA's Solar Dynamics Observatory (SDO)
    • The Sun Now - several very high-resolution images, mostly in ultraviolet wavelengths; includes video of past 48 hours under each image, listed as "48 hr MP4" (for example, the latest 17.1 nm UV video)
    • SDO Gallery - lots of great images and videos packed with interesting solar features
    • SDO Daily Movies - choose the date and wavelength for 24-hour video loops
    • SDO Featured Movies - lots of short video clips, often with specific solar features such as flares or prominences highlighted
  • Interactive: Compare Sun Images Side-by-side
  • NCAR's High Altitude Observatory (HAO) Mauna Loa Solar Observatory
  • NASA's & ESA's (European Space Agency) Solar and Heliospheric Observatory (SOHO)
    • Latest SOHO Images
    • Best of SOHO Gallery
    • SOHO Movies Gallery - including sections on flares & CMEs, sunspots, and filaments & prominences

Evaluate students' ability to observe and identify features.

There are three opportunities to assess student learning during this lesson:

1. During the Explore phase, do students make careful observations of the images, noticing and describing details in the photos?
2. During the Explain phase, do students correctly identify features by name in the images?
3. During the Extend phase, can students identify the features they've learned in different images that they haven't seen before? During the scavenger hunt, are they able to find images with the features they have learned to identify?

If you'd like a more structured writing assignment as an assessment option, here's a sample writing prompt and rubric for grading:

You have been transported through time to the ancient city of Ugarit where you meet an ancient astronomer who made the first known record of a solar eclipse. The astronomer is amazed about the features that she was able to see during the total solar eclipse. You have only a short time to explain the features of the Sun you have learned about in this lesson. Your written explanation should include the following:

• The names of the features of the Sun and the major regions or "parts" of the Sun 
• Describe the features using words and/or drawings.
• The important solar features on images of the Sun using links to images you found on the web.