Exploring the Dynamic Nature of the Sun

Students develop an understanding of the dynamic and variable nature of the Sun by comparing and contrasting images that vary with respect to time, scale, or technology, and share their findings with peers. The class discusses the implications of the Sun as a variable force of nature and brainstorms a list of questions that have been raised by the comparison of images. During the following class period, the instructor facilitates a slide show to further student understanding of the dynamic processes of our Sun and offer explanations to student questions.

Learning Goal

Students will learn that the Sun changes over time.

Learning Objectives

• Students will make, record, and communicate observations
• Students will compare and contrast the appearance of the Sun with respect to the variables of time, scale, and technology
• Students will develop an understanding of how scientific instruments and technology can be used to understand different aspects of the Sun

Materials

• Sun Image Cards - Exploring the Dynamic Nature of the Sun
• Exploring the Dynamic Nature of the Sun - Student Page
• Exploring the Dynamic Sun slide deck
• Computer and projector
• Whiteboard
• Pen/Pencil

Preparation

• Print the Sun Image Cards (pages 1-3) in color and cut along dotted lines. Laminate the cards if you wish to reuse them. For large classes, make two sets of cards. Cards MUST be printed in color for this lesson. If you cannot make color prints, share the Sun Image slide deck with students.
• Copy the Student Page for each student pair.
• Prepare to facilitate Exploring the Dynamic Nature of the Sun slide deck by reviewing the annotations of each slide.

Directions

Introducing the Lesson

1. Explain that scientists often make and record observations. Some scientists record observations of images of the Sun in order to keep a record of its variations over time. They use various technologies to make images of the Sun.
2. Explain that in this lesson students will explore the ever changing Sun by observing and describing images.

Facilitating the Lesson

1. Convey directions of the activity via modeling:
   • Show Sun Image #1 from the slide deck (slide 2).
   • Ask students to look at the images and share their observations about similarities and differences.
   • Explain to students that they will work in pairs or small groups to compare and contrast images and that each group will share briefly their observations with the class.
2. Divide the students into pairs and provide each with a Student Page and one Sun Image Card.
3. Allow students 10-15 minutes to make observations and answer the questions on the Student Page. As students work, circulate throughout the class and help students express their ideas and observations with words.
4. Have each team describe the Sun image they observed to the class using slides 2-9 and the answers they recorded on their Student Sheet. Focus on sharing the similarities and differences that they observed. (Note: team presentations may need to continue into the second class period.)
5. After all teams have reported, ask students to brainstorm a list of questions about the images, or solar processes. Record a list of all the questions on the board to reference as necessary.
6. Present the solar images and content about features of the Sun, using the slide deck (slides 10-17). Reference student questions as information is provided that might provide answers. Content and images on these slides (10-17) was prepared by scientists from NCAR's High Altitude Observatory and the UCAR Center for Science Education.

Background

Details about each set of images are below (and also included in the slide notes). Images are from the UCAR Digital Library and the HAO Collection.

Set 1

• Left: A solar prominence is an eruption of hot gas from the upper chromosphere or the inner corona of the sun. Some of this erupting matter escapes into space. Solar prominences are of higher density than the surrounding portions of the solar atmosphere, but their temperatures are lower.
• Middle: This color-enhanced image shows a solar flare (bright splash, lower left) near the lower of two sunspots (dark circles). Fingers of plasma sweep downward on the left are believed to trace the magnetic field's orientation in the solar chromosphere. This photograph is in visible light. (Big Bear Observatory, Big Bear, California)
• Right: This color-enhanced image shows plasma bursting from the surface of the sun. Image taken in visible light. (National Solar Observatory, Sacramento Peak, New Mexico)

Set 2

• Left: The sun's corona, viewed in polarized light, was photographed on April 12, 1980, by the coronagraph-polarimeter aboard the Solar Maximum Mission satellite. ( High Altitude Observatory (HAO, NCAR)
• Middle: This solar corona, viewed in polarized light, was photographed on April 14, 1980, by the coronagraph-polarimeter aboard the Solar Maximum Mission satellite. (HAO, NCAR)
• Right: This solar corona, viewed in polarized light, was photographed in May 1980 by the coronagraph-polarimeter aboard the Solar Maximum Mission satellite. (HAO, NCAR)

Set 3

• Left: NCAR/HAO photo of a total solar eclipse on 30 June 1973. The corona, much dimmer than the sun itself, can only be seen when the disk of the sun is covered. This photo shows details of the corona's structure, from its innermost part to its outer region. (Loiyengalani, Kenya)
• Middle: The total solar eclipse as photographed on 16 February 1980, from Palem, India. It was taken with a special camera designed by Gordon Newkirk of NCAR. The corona, much dimmer than the sun itself, can only be seen when the disk of the sun is covered. This photo shows details of the corona's structure, from its innermost part to its outer region. (Palem, India)
• Right: A total solar eclipse photographed on June 11, 1983, from Java. The corona can only be seen when the disk of the sun is covered. This photo shows details of the corona's structure, from its innermost part to its outer region. (Java, Indonesia)

Set 4

• These three images are the same view of the solar corona that have been colored differently using a computer. The various colors show differences in density (HAO/Mauna Loa Solar Observatory in Hawaii).

Set 5

• Left: The Sun in white light. This image shows few details of the Sun beyond the sunspots. However, by careful observation of sunspots, early observers learned that the Sun, like the Earth, rotates.
• Middle: This image of the Sun was created by use of a filter centered on the K line of Ca. The use of this filter highlights the magnetically active areas on the Sun. Cool, dark sunspots are surrounded by hotter, white plages. Sunspots although cooler than their surroundings are still hot at 4000 degrees K. Notice also that sunspots remain near the Sun's equator.
• Right: The use of a hydrogen filter reveals activity above the surface of the Sun. In this image, filaments and prominences stand out. Both features represent cooler, condensed gas high in the solar atmosphere.

Set 6

• In these images, the solar corona is visible in X-radiation. These images, from the Yohkoh satellite, show how the corona varies with the 11-year solar activity cycle. The bright corona at the left shows high activity, which may be associated with magnetic storms on the Earth and other effects. The dark corona on the right shows low magnetic activity associated with a solar minimum of 1995. The plot at the bottom shows the time variation. (Yohkoh Gallery SXT Image http://solar.physics.montana.edu/sxt/)

Set 7

• This set of images shows a coronal mass ejection from 10:04 to 13:34 on August 28, 1980. Large ejections, send material into space at rates of 1000 km/s (although average rates are 400 km/s). The helmet streamer, seen in the lower left of each image, responds to the CME event by swelling. The material from the CME explodes outward from the origin of the streamer.

Set 8

• This image compares and contrasts sunspot activity to the extent and position of the corona seen during an eclipse. The images in the top row show decreasing solar activity viewed in X-ray by the Yohkoh satellite. The lower set of images represents eclipses from 1966 through 1988 and includes a coronal image created from the Solar Maximum Mission of 1985. The decrease in solar activity seen above is reflected in the change of position and extent of the corona as seen during an eclipse. The graph in the center of this image compares a 27-day cycle to an annual cycle.

Extensions

• Provide students additional images that challenge their observational skills.
• Have students create their own graphic organizer to remember the similarities and differences between the images and image sets, for example, a Venn diagram.
• Challenge students to find examples of images that show an object that changes over time, changes with scale, or changes depending upon the technology used. For example students might find images of a human or animal photographed using visible light and imaged with x-rays.