Solarscapes: Sunspots and Rotation

Secondary School Activities About the Sun

Author Beverly Meier Science Teacher Boulder Valley School District

Project Coordinators Paul B. Dusenbery Space Science Institute

Carol McLaren Science Discovery Program/CU

Christine Morrow Science Discovery Program/CU

Ramon Lopez University of Maryland

Letter to Teachers Activity Evaluation Form Introduction and Information for Teachers Activity 1: Features of the Sun Figure 1: Sun’s Features Figure 2: Ultraviolet, Visible & Solar Eclipse images Figure 3: Solar Flare, H-alpha Sun images Activity 2: Sunspot Number Variations Sunspot Chart #1: 1700 - 1888 Sunspot Chart #2: 1889 - 1995 Activity 3: Determining the Rate of Rotation and Period of Rotation Activity 4: The Sun’s Period of Rotation Figure 4: Solar Grid Overlay Figure 5: Sun Rotation Series

The Electric Space Exhibit project gratefully acknowledges the efforts of Beverly Meier and Ramon Lopez, who were the principal authors of this guide, Carol McLaren, the project coordinator, and Christine Morrow, assistant coordinator. We also wish to acknowledge the creative talents of Steve Mercer, who was responsible for the layout of Solarscapes. We wish to thank John Rundell, a middle school teacher at the Boulder Valley School District, who helped to pilot early versions of the curriculum in his classroom. Gary Heckman, at NOAA’s Space Environ- ment Center, provided insights into the workings of the Sun as well as the solar grid used in Activity 4.

This material is based on work supported by the National Science Foundation under Grant No. ESI-9453798.

Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the National Science Foundation.

Dear Teachers:

Dedicated to excellence I hope that you find this middle school curriculum both inspirational as well as rewarding in space science for you and your students. The primary author of this work is Beverly Meier, an eighth research & education grade teacher in the Boulder Valley Public Schools. The star of the show (no pun intended) is of course our very own Sun. You will be able to explore the Sun using a variety of electromagnetic wavelengths. These waves act like “fingerprints” helping scientists and students to decipher the dramatic changes which occur on the Sun. You and your students will be able to open up the Sun to see phenomena many people have never seen before. Your students will also be able to calculate the period of the so-called solar cycle (which is the rising and falling of the number of sunspots) and even predict the shapes of the next two solar cycles called 23 and 24. The last activity in this unit is calculating the Sun’s rotation period using sunspots.

Our goal is to provide activities that are fun for students and convenient and easy for teachers to use. The reading level is aimed at the middle school age group. However, some of the questions that follow each activity can be challenging to high school students. Mathematics is incorporated into Activities # 2, 3 and 4. I hope that you will find these activities flexible enough to adapt to your teaching and classroom style. An on-line version of the curriculum can be found at http://www-ssi.colorado.edu/Education/ ResourcesForEducators/1.html. You can download the necessary images needed for Activities # 1 and 4 or you can order a set by contacting me at the Space Science Insti- tute.

Your opinions and evaluation of these activities are vital to us. I am particularly inter- ested in your opinion of the rubrics and the use of the learning cycle. With the assistance of the Science Discovery Program at the University of Colorado/Boulder, I plan to update and improve Solarscapes based on your comments and hope to add activities to the series in the future. An Evaluation Form is included in the “Information to Teachers” section of this document. Please complete the form after you have used the Activities and return it to us so that we can implement your suggestions for improvement.

Best Wishes. 1540 30th Street, Suite 23 Boulder, CO 80303-1012 Sincerely,

Phone: 303.492.3774 Fax: 303.492.3789

Paul B. Dusenbery, Ph.D. A non-profit public benefit institution Executive Director

We often teach our students that the Sun sustains life on Earth. Indeed, without its warmth, energy and relative constancy, life on Earth could not exist. While astrophysicists classify the Sun as an average star in terms of size, temperature and brightness, it remains of central impor- tance to us, the inhabitants of Earth. Because of the Sun’s impact on our lives, it naturally engenders interest and curiosity. What is it made of, how far away is it, will it ever stop burning, will it go super nova? These are questions that a curious middle school student may ask.

This curriculum is intended to be a short and focused study of the physical nature of the Sun. It is written to accompany the traveling exhibition entitled, “Electric Space: Bolts, Jolts, and Volts from the Sun.” Beginning in September, 1996, Electric Space is traveling to museums across the country. The exhibit calls attention to the fourth state of matter, plasma, and to the idea that “space is not empty:” it is filled with electromagnetic fields, charged particles and the interplay between these two. Just as we speak of living things existing in an environment, we can also think of Earth as existing in a space environment. This environment, created by the Sun, is a vast magnetic bubble called the heliosphere. The Sun’s heliosphere extends far beyond the solar system. Thus, the Sun encases Earth in its sphere of influence, surrounding us with its magnetic field, subjecting it to the constant solar wind, and occasionally pelting it with great bursts of charged particles that arrive following mass ejections and solar flares from the Sun.

This curriculum is aimed at the middle school level and focuses on the observable features of the Sun. What can we learn by looking closely at images of the Sun? Is it just a fiery ball or are there discernible features? The curriculum then zeros in on the most prominent feature of the Sun, sunspots. If we count sunspots over the years, does a pattern emerge? Why is this pattern important and can we predict it? As an embedded assessment, students are asked to predict the beginning and end of the next two sunspot cycles and the number of sunspots at each maximum. Students are invited to submit their predictions right along with solar scientists to the Space Environment Center located in Boulder, Colorado at the National Oceanic and Atmospheric Administration. Finally, students are asked if they can learn anything about the rotation of the Sun by observing the movement of sunspots across the surface of the Sun. Can they calculate how fast the Sun rotates? Can they apply this knowledge to the rotation of other objects in the solar system?

In order to use this curriculum you will need several images of the Sun. These have already been selected for you by the Space Science Institute to illustrate the essential characteristics of the Sun. If you wish, you may also access them on the World Wide Web at: http://www- ssi.colorado.edu/Education/ResourcesForEducators/1.html. Should you not be able to obtain the images from the WWW you may contact the Space Science Institute at 1540 30th Street, Suite 23, Boulder, Colorado 80303-1012 for details on image prices.

Introduction 4 © Space Science Institute, 1999. All Rights Reserved We encourage you, the teacher, to use these written lessons as a jumping off point. Change them as you wish to fit your own style of teaching. Mix your style of delivery to engage all learning styles. Have your students follow-up their questions with information searches in the library and on the WWW. Most of all, have fun!

We want to hear from you as to how Solarscapes worked for you and your students. With this in mind, there is an evaluation form at the end of this section. Please take the time to fill it out and return it to The Space Science Institute.

General Philosophy, Intent, and Internet Version of Solarscapes

The general philosophy behind Solarscapes is that students should have the opportunity to learn science in a manner not too dissimilar from the way in which science is done. Scientists continually assess prior knowledge, explore new data and ideas, compare prior knowledge to the new information, and try to synthesize all of this into an enhanced understanding of what they are examining. In short, scientists are constructivists. We therefore take a constructivist viewpoint with regard to these activities. To use them as intended, teachers must be “the guide on the side” as opposed to “the sage on the stage,” an approach that even the most exemplary teachers continually refine by reflecting on their practice.

Prior knowledge is examined in every activity, and a key self-assessment for students is to compare their prior knowledge with their understanding after the activity. Students are expected to work on the activities in groups, although each is expected to keep a small portfolio for individual assessment. The teacher as facilitator is expected to “float” among the groups, probing with questions and continually assessing in order to help groups focus on the questions at hand and thus to direct them to achieve the learning goals of the activities on their own terms. Our vision is a student-centered environment, where all students achieve some measure of success in these activities.

The intent of Solarscapes is to provide a supplement for middle school science whose topic is the Sun and its features. It is intended that these activities (four in number) take about one to two weeks of class time, and that some activities will be spread over more than one class period. While the activities are supplemental and may be used independently of each other, Solarscapes was conceived and designed as an integrated experience that builds from lesson to lesson and ideally should be used as a group. We hope that inquiry drives student understanding, though we recognize that inquiry is limited in these activities (especially the first), partly by design and partly by the constraints placed on any such supplementary material.

While all of the materials needed to do the activities are present within this package (assuming some photocopying), all of the images and data are available over the Internet at (http://www- ssi.colorado.edu/Education/ResourcesForEducators/1.html. If students are using the Internet, we recommend that they be allowed extra time at the end of the last activity to gather additional information about the Sun (such as current images of the Sun), starting with the links at the Space Science Institute’s home page. They should use this information to write a report on the Sun that could be part of their portfolio (especially for students who contract for a better grade), or a separate assignment. Using the Internet to access the images and additional information will Introduction 5 © Space Science Institute, 1999. All Rights Reserved increase the time needed to complete Solarscapes, but it will provide students with the opportunity to utilize technology and gain experience with accessing information over the Internet.

Goals for and Assessment of Student Learning

Solarscapes has two clear and assessable goals. These are:

Goal 1 - Students will learn that the Sun has many features, including sunspots, and that sunspots vary over time in a regular and somewhat predictable fashion (the sunspot cycle).

Goal 2 - Students will learn that the Sun rotates and with what rotation period.

We view good instruction and good assessment to be indistinguishable. Thus, in all lessons there is an assessment of student understanding. Rubrics are provided with each lesson to guide the teacher in assessing students. Students should be informed of the rubrics for scoring each lesson at the start of the lesson. All students should also keep a portfolio of all of the material, observations and analysis done in these activities. Portfolios may be judged at the end of the activities by the rubric below:

Portfolio rubric (satisfactory = 2)

0 - Student does not keep portfolio. 1 - Portfolio contains most handouts, images, data, and tables. 2 - Portfolio contains almost all handouts, images, data, and tables, plus observations, and other requested materials (indications of prior knowledge, what was learned in an activity, etc.).

Students could also be allowed the option to contract for a grade based upon their portfolio and successful achievement of the lesson assessments. Better grades could be secured by keeping a more detailed notebook that would include additional writing assignments according to the discussions with the teacher, perhaps in conjunction with a teacher from a different subject area.

Lesson Structure

Each lesson has a specific stated goal. The lesson goals are articulated to lead to the two main goals of the unit. In fact, the end of unit goals were developed first, then these were backmapped to determine what knowledge and skills students would need to achieve the goals. Then the experiences students need to acquire the knowledge determined the lessons. These lessons were trial taught by one of the authors.

The lessons have been constructed on a learning cycle model. For our purposes we define the phases of the learning cycle to be:

1. DISCUSS: (get out prior knowledge, set up activity/lesson)

2. EXPLORE: (do activity)

4. APPLY: (come to conclusions, communicate to others, identify next steps that lead to next Discuss phase).

Each phase is explicitly discussed in a lesson. The learning cycle concept is also in play over the entire unit. This material is contained in the section for the teacher. Following that is a reading for students, and a student worksheet containing directions for the activity.

Connections to Science Standards

The design of this mini-unit has been guided by the various standards documents - National Science Education Standards, Benchmarks for Science Literacy, and the National Council of Mathematics Standards. In this section we will present a brief overview of the correspondences between the activities and the standards.

National Science Education Standards:

Solarscapes is only a one-to two-week long extension to a regular Earth-space curriculum. Thus, Program and System Standards are not within its purview. Professional development is also not addressed except as implied in the statement of philosophy above. Beginning with the Teaching Standards we find that the unit is aligned with standards A-E, such as “Select teaching assessment strategies that support the development of student understanding...” (A) and “Nurture collaboration among students” (E). Standard F is not addressed. Similar correspondence can be found with the Assessment Standards, since the material uses assessments that “...are deliberately assigned” (A), that “..focus on the science content that is most important for students to learn” (B), and that “assessment tasks are authentic” (C).

In the Content Standards, Science as Inquiry is addressed since every standard referred to on page 145 can be seen in some fashion in Solarscapes. In the Earth and Space Science Standard we find that students should know that “Most objects in the solar system are in regular and predictable motion...” By studying solar rotation (and perhaps the rotation of other bodies) students will address this issue. They will also learn that the Sun is a variable star, an important aspect when one considers that students are to understand that “Energy from the Sun transferred by light and other radiation is the primary energy source” for Earth.

In terms of the three remaining Content Standards (Science and Technology, Science in Personal and Social Perspectives, and History and Nature of Science) there is some (but not great) align- ment. The weakest is with Science and Technology, since there is little in the way of technological design in this unit. If the unit is done over the Internet there may be a greater, though indi- rect, connection to technology. There is a somewhat greater relationship to the last two Content Standards through the discussion of the effect of solar variability on climate and the history of sunspot observations that is found in the student readings.

There are a number of places in which Solarscapes addresses the Benchmarks. Let us begin with those areas that are common to science generally. Examples range from 1C (p.17), addressed by the student reading of the Chinese discovery of sunspots and their ancient records, 3A (p.46) where it is clear that “Technology is essential to science for such purposes as access to outer space...”, and 11C (p.274) where student probing of the sunspot cycle through graphical analysis shows that “things that change in cycles, such as seasons or body temperature, can be described by their cycle length or frequency.”

There are specific relationships to the content of Solarscapes, such as 10A (p.240) where students are to learn that “Telescopes reveal that…the sun has dark spots…” In addition, these materials provide a vehicle for discussions that relate to content not further pursued in Solar- scapes due to its scope. For example, the rotational motion of bodies in the solar system can become a forum for discussing that “In the absence of retarding forces…an object will keep its direction of motion and speed.” 4F(p.90).

To summarize, Solarscapes is aligned with these Benchmarks for grades 6 through 8:

• 3 A #2 • 2 A #1, #2 • 10 A #3 • 11 B #3 • 11 C #6

Saturn and its Moons

Its orbit around the Sun Other factors affecting Guide to Teachers density and mass

QQQQ¢¢¢¢

QQQQ¢¢¢¢ Goal: Students will learn that the Sun contains many complex features and compare this to their own prior knowledge about the Sun.

This activity introduces Solarscapes and allows students to learn about various features on the Sun, including sunspots. It functions as a DISCUSS phase for the Solarscapes unit overall.

Caution: Never look directly at the Sun. To view the Sun, project an image through a card or sheet of notebook paper, pierced with pin sized hole, onto a sheet of white paper. The Sun’s inverted image will appear on the paper below.

MATERIALS NEEDED

1 23 99 3 81 9 10 92 38 019 238 20 3 94 85 28 40 5 582 90 59

• One copy of the student activity, “Features of the Sun” (included) • A schematic diagram of the Sun (Figure 1) and two sets of images that illustrate the Sun as seen in different wavelengths (Figures 2 and 3, included) • A photocopy of the student activity, preferably one copy per student. Provide the worksheet first, then the rest of the text once students have drawn their initial picture of the Sun • One photocopy of labels per group of students (original included) • Colored pencils • Scissors • Large sections of paper (newsprint, etc.)

XXXXXXXXXXX

XXXXXXXXXX DISCUSS: Ask the class to discuss what they know about the Sun and what they would like to know. Brainstorm a list of ideas and ask the students to record this list in their notebooks. Working in groups of three or four, have students draw the Sun with as many features as they know about, and make a list of those features. Students are to write down these ideas and copy the group diagram in the space provided in their STUDENT WORKSHEET.

EXPLORE: After that, ask the students to read the “Features of the Sun” (in the Student Guide section). Have them compare what they read to their picture. As they read, they are to locate the boldface words from the reading that are on the accompanying schematic diagram titled “The Sun” (Figure 1).

APPLY: Students are to place labels of the Sun’s features provided on the photographs in Figures 2 and 3 so that the arrow on the label points to the name of the feature where it is located. They are to identify as many different features in the time allowed (including locating the same feature on as many different photographs as possible).

REFLECT: On a large sheet of paper, each group of students is to draw and color a sketch for the exterior features of the Sun that were identified on the photos. The drawings are to be as realistic as possible. They then compare their new drawing to their initial drawing. How many features did they know about and how many were new? Students are to write down their comparison. The drawings are to be posted and students are to take a “wisdom walk” (without talking, go around the room and view the other group drawings). Students then are to use Think-Pair-Share with a member of another group to briefly discuss what they observed during the wisdom walk. Observations on what they learned are to be recorded in their portfolio notebooks, along with questions they have. Students are also to write a short essay to be turned into the teacher that answers the “Problem” question(s) at the beginning of this activity.

2 Teacher Guide, Activity 1: Features of the Sun © Space Science Institute, 1999. All Rights Reserved. t a n y i h l e t h h s . v t i s i e g u t i r s . o w o e h o r y l p h m g a y a p s r r p l g x n o s e s r i F e u n o n e s e e n e d r m r r t e t f e e i a a t a a o r l l f a e f a m s r r o o s l t n t e a t r l o S F e n s n a s s o p l e r r u e s s a c o u a r o e n l s n c a l e l u o c o m e h r F t A c o a S S s s t e - a c e r : d r g e a u k a f a s t r h e n t c a e s n e h u t i s e D r r g n t t v n e w o i e s a e . t r u r h o s h t e c a e t d m h t p e s r n a h e a y s t l r a a l s o g . h s a h s i e e i i t e e s f A e e e h r b h r h g t - e g c c t f e b e e p m e s c a n m n r t s v l s h n o k i He d n e e t e i l r n o o t e p p g l e n f h n o n e e s b o - i t i e n u m p s t T a i o e n p g h h m s o t o h m s i m t g t n r r g a o n o m . i g o s n r i o l a s h r i i r l u r h r o n n l u u u t w j b p p p F L P P C o o a S s s s o l l h t s c e o i e l b w f t h e o o n i h o w h t a e s v i s , l e a f g e a U r h h n o r t t t l u e n e A n u e a h S o c v p y . i e m s s e s o e f g e e e n h r o m b i e t c c r o e e r a t i t n n m r f t s h t t e t e x o n a o n p s x i l r n o n s i i u e Ea e h e u h p j o e . t c s t g n m s m g n d i a a n n o a o o a e e i r h l r u u h r e h m s p p t P P T i i G S S s d l e e u h b t o s - o - s h w l e . a t o s a t i s a n n h r h s n h u o s e t s r a S w t e e c t o p m s l i e h c e h a l n s s l t l p . h g i l e a e e o t c i l e r h a n l c c t c i m p e H s EV n n d e f S r s a d s e e l r o e t r n e s a a u n n g h e a i i a u h n n t n t l o c e o t o o m o m m t w n r l r r S s o o o r e o e o e o o r r l h r u e h b p t A P P H c C C s s . y s e a w e h g r t y o t a e h h r g e s d h g e s n n s i l t n i l T n u o e u a - o d a s u o e p . S n t c e n c s S s i r u e e n d t e h e t o e b l l u a r h n e h e r i h i t W S b k p r f u i r s f e f r w s s a . o o h c s e i o o t s d i t e t p t s o s o m e Ve s h r o e l n h t e p o a o p n b t o p s s g e s i i n g o a n s p n e a a g e i h u p r u e h h m r t t P V i m a a S s

3 Teacher Guide, Activity 1: Features of the Sun © Space Science Institute, 1999. All Rights Reserved. f o l l a d s n e o a s o l . s d s a e t t r t s n a u a e . p r b t a d i , n m u r t 3 o o e # t c c S i r c t e a , g h d s h t d n e t a e e i e r e s r t n b h s o y i i h e d t n a o l t r e a d n s c c f o c c d i s i u a s e h s c s o e u v r d t t e e i S d y d o u n s d n l t i d r o r n l e w e n a r p r a a a s e y y a e p e u l l t c e f l t . t t m , i k . r n h t c a c c a p s r n n y p e s t r l e e e a u i o o t t d f r r y w l j g s o n a r r r a u a a a f s r l t u n e i r e o o l e e o r m n v l c c d d G a S S w o s r h t e . u i d o r a . w e o y t t y u s a a n d e t e s s c u l c d i t s e a a b S s a u r d e a o e d u n n f o t i i e o s t o l a m r i F b y y e p u s l l t f a y t t m : e o f n n c c a p r i r e y t r o e e 1 u o u d r r s j n t g r o r r u a a e a a r o t i o o y e e f d r m i f c c d G S t i m o v s h i t _ e o i r t _ b a i e w _ c r l ) o r s _ s c b " n l o e i s y _ s A 2 u a s c e a _ s e " s n S u r d s e _ ) s i e r r d u f _ a e t " y y h u o . o l l _ e o t a 2 r e t t s s r d _ ' r a f e p c c e " t e e f e _ p m t e e v n h f . r r _ s a p r a a t e c e r r m r y i e r c _ u o i ; t d s i j o o o a g a t h _ i o e l s u a r c d c c a r r c n _ t i s v o n n n n e a _ m i i i i w e d G S s b e d i _ t u u h _ n t c _ s e a _ R e d r t _ . i e u p r _ t p g m u t t s _ w a o o o y _ f r n r r i n n p i _ g g o o t _ a s r d i f c e e i _ e i d t o o d _ e m a t d _ e c t n e p l c _ i n o . p a S u c _ e m y i u o e d _ d t a l o g r k o _ s u r a ( t r a a s _ o t p p e G S _ g M n _ ( e _ : s t _ ' m E _ n s n S s e _ u e U s s m S : e e s s e r D s f h A t e u m E o t s l a T s a n a N S s e m A u o f t ) ) e E a d s s r r i n p y ( ( s G e ' v u g u a i k k t d G n o s a s s d a i u r s u a a t U n e E D I f T01234 T01234 G S S S

Problem: What do the following features look like on photographs of the Sun: sunspots, plages, solar flares, prominences, filaments, the corona, helmet streamers, and coronal holes? How do these features compare and contrast?

Introduction

Our Sun is a middle-aged, medium sized star, big enough to hold a million Earths. The ancient Greeks thought that the Sun was a perfect sphere of fire. Today we know that the Sun is a variable (changeable) star that produces life giving light and heat as well as harmful radiation. It causes space weather that can harm astronauts working in space and can interfere with satellites orbiting our planet.

Features of the Sun’s Surface and Atmosphere:

Although the average distance from Earth to the Sun is a whopping 149,600,000 kilometers (93,000,000 miles), careful observation from Earth reveals a surprisingly large number of different visible features. The most obvious and best known feature is the Sunspots sunspot. Typically moving in groups, these N dark (in visible light), planet-sized features S have been known to humankind for centuries. As sunspots form and disappear over periods of N days or weeks, they also appear to move across the Sun’s surface. Composed of strong magnetic fields, S sunspots are shaped much like a horseshoe magnet that S rises from below the Sun’s surface. More accurately, however, flexible magnetic tubes, or “flux tubes,” probably give rise to the magnetic fields that we see. The rising hot gas is trapped by the N sunspots’ intense magnetic field which cools the sunspots from 6000 ½C to about 4200 ½C. The cool area appears dark compared to the area around it. 1 Student Guide, Activity 1: Features of the Sun © Space Science Institute, 1999. All Rights Reserved Thus, from Earth, we see spots on the Sun. In some photographs, we can also see light colored areas around groups of sunspots that resemble tufts of cotton candy. We call these fluffy looking fringes plages.

Sunspots are the source of massive releases of energy called solar flares, the most violent events in the solar system. In a matter of minutes to several hours, a solar flare releases about 10,000 times the annual energy consumption of the U.S. Solar flares give off radiation that includes X-rays, ultraviolet rays, and charged particles called protons and electrons. This sudden surge in radiation can damage spacecraft and even give a dose or radiation to travelers flying in airplanes over the polar regions.

Also visible for only minutes, are granulations in the Sun’s photosphere. Granulations are rising and falling columns of hot gases that look like fluffy marsh- mallows arranged in a honeycomb pattern. The tops of these granules form the Sun’s “surface.” Al- though we refer to the Sun’s “surface” as the photosphere, you probably know that the Sun has no solid surface, unlike Earth. It is Courtesy of the Lockheed Palo Alto Research Laboratory and Courtesy of the Lockheed Palo in Japan. Astronomical Observatory the National an uneven sphere of glow- The bright areas in the X-ray image from the Japanese Yohkoh ing, hot gas! satellite are called “active regions,” which contain hot, dense gas. They are also the source of the most intense X-ray eminations. The dark areas are coronal holes.

Just as the Sun disappears behind the Moon during a total solar eclipse, a flash of bright red light appears. This colorful layer of the Sun, called the chromosphere, becomes visible for a brief instant. Although we know little about the chromosphere, there are curious, permanent features of the chromosphere, called spicules, that we can study in more detail. There are so many of these fine, bright, hairlike features, that they are always visible near the Sun’s edge, even though an individual spicule lasts only minutes. Like sunspots, spicules rise and fall vertically above the Sun’s surface.

One of the most spectacular features of the Sun are solar prominences. They appear to stream, loop and arch away from the Sun. The most recognizable prominences appear as huge arching columns of gas above the limb (edge) of the Sun. However, when prominences are photographed on the surface of the Sun, they appear as long, dark, threadlike objects and are called filaments. Like sunspots, prominences are cooler (about 10,000 ½C) in relation to the much hotter background of the Sun’s outer atmosphere (about 1,500,000 ½C). Prominences can also erupt from the Sun with a tremendous burst of energy.

2 Student Guide, Activity 1: Features of the Sun © Space Science Institute, 1999. All Rights Reserved If you have seen photographs of a solar eclipse, then you have probably noticed a bright halo around the Sun, called the corona. Sometimes parts of the corona appear to be missing. Logically, we call this area a coronal hole. Scientists believe that the solar wind, a million mile per hour gale that blows away from the Sun, originates in coronal holes. Unlike wind on Earth, the solar wind is a stream of ionized (electrically charged) particles speeding away from the Sun.

The Sun’s corona changes with sunspot activity. When there are more sunspots, the corona appears to be held closely to the Sun; when there are fewer sunspots, the corona streams out into space in a shape that resembles the spike on a warlike, peaked helmet called helmet streamers. While helmet streamers are long-lived, their demise often occurs abruptly through massive and powerful eruptions called coronal mass ejections (CMEs). Courtesy of the Los Alamos National Laboratory Courtesy of the Los Artist’s conception of a coronal mass ejection moving away from the Sun toward Earth.

These huge clouds of hot solar gas and magnetic fields are often associated with solar flares. They can cause magnetic storms when they hit Earth’s magnetic field and damage human technological systems in space and on the ground. For example, in 1989, the Quebec province in Canada suffered an electrical blackout because many transformers were destroyed by a large magnetic storm. That one storm caused many millions of dollars worth of damage. A powerful solar flare erupted from the Sun about three days before the start of the storm at Earth. Even when the Sun is not too active, solar storms can cause problems. A magnetic storm on January 11, 1997 was blamed for the loss of a $270 million dollar AT&T communications satellite. This moderate storm was caused by a coronal mass ejection that erupted from the Sun even though there were no noticeable sunspots.

Features of the Sun’s Interior

Core - central part of the Sun where hydrogen fuses into helium to give off energy. Radiation zone - energy from the Sun’s core travels outward through this area. Convection zone - hotter gases rise and fall as they are heated from the radiation zone below much like a boiling pot of water.

Procedure:

XXXXXXXXXXX 1. Use the following process to learn the features of the Sun. Working in groups of three XXXXXXXXXXX or four, draw the Sun with as many features as you know about, and make a list of those XXXXXXXXXX features. Write down these ideas and copy the group diagram in the space below. When your group is done, send someone to get the materials for the activity.

2. In your group, read the description of our Sun (“Features of the Sun’s Surface and Atmosphere”) provided in your Student Guide. Compare what you read to your group’s picture. As you read, locate the boldface words from the reading that are on the accompanying schematic diagram titled “The Sun” (Figure 1).

4 Student Guide, Activity 1: Features of the Sun © Space Science Institute, 1999. All Rights Reserved 3. Cut out the accompanying labels that name the features of the Sun (There are more labels than you need in case some get lost.) Place labels of the Sun’s features on the photographs in Figures 2 and 3 so that the arrow on the label points to the name of the feature where it is located. You are to identify as many different features in the time allowed, including locating the same feature on as many different photographs as possible.

Note: Identify a feature only once per photograph even though it may appear in several different places.

4. As a group, on a large sheet of paper, draw and color a sketch for the exterior features of the Sun that were identified on the photos. The drawings are to be as realistic as possible. Compare the new drawing to your initial drawing. How many features did you know about and how many were new? Write this information in the space provided.

5. Post your group’s drawing somewhere in your room as directed by the teacher. When all the drawings are posted, you will take a “wisdom walk” (without talking, go around the room and view the other groups’ drawings).

6. Find someone who was not in your group to pair up with. Spend a minute thinking on your own about what you saw in the diagrams of the Sun. Then discuss your observations and ideas with your partner. Record your ideas in the space provided, along with any questions you might have about features on the Sun.

5 Student Guide, Activity 1: Features of the Sun © Space Science Institute, 1999. All Rights Reserved 7. In the space provided below, write a short essay that answers the “Problem” question(s) at the beginning of this activity.

Psrominences Ssunspot Garanulation Ceoron Plag

Pshotosphere Feilament Cehromospher Solar Flar

Hrelmet Streamer Hrelmet Streame Hrelmet Streame Helmet Streame

Ceoronal Hole Ceoronal Hol Ceoronal Hol Coronal Hol

Saturn and its Moons Its orbit around the Sun Guide to Teachers Other factors affecting density and mass

QQQQ¢¢¢¢

QQQQ¢¢¢¢ Goal: Students learn about sunspot variations and the solar cycle, and are able to predict future solar minimums and maximums.

This activity focuses on one feature of the Sun seen in the last activity, sunspots, and examines their variation over times much greater than a solar rotation (about 25 days). It functions as an EXPLORE phase in Solarscapes.

MATERIALS NEEDED

1 23 99 3 81 9 10 92 38 019 238 20 3 94 85 28 40 5 582 90 59

• One copy of the student activity information and worksheet (included) • Table of yearly sunspot numbers (Charts #1 and #2, included) • A photocopy of the student activity, preferably one copy per student. Provide the worksheet first, then the rest of the text once students have discussed their initial ideas • Three sheets of graph paper per group of 3 students • Colored pencils • Ruler • Scissors

XXXXXXXXXXX

XXXXXXXXXXX DISCUSS: Students discuss what they know about sunspots and their variations. This

XXXXXXXXXX allows them to revisit some material from Activity 1. Many may know that the number of sunspots changes over time, or even that the number changes in a regular cycle. Stu- dents then report a few ideas from their groups, facilitated by the teacher.

EXPLORE: Provide students with activity materials and text. Students work in groups of three. They begin by reading about sunspots and their relationship to Earth. Each student prepares a graph using the procedure in the student worksheet. They plot the number of sunspots for each year using Charts #1 and #2, join their graphs and observe the resulting pattern. The teacher should assist students who are having difficulties producing a correct graph of the data to ensure that all students who wish to produce a correct graph do so.

NOTE: Since they will be taping these graphs together, make certain that all three students in each group use the same scale for both the time in years (x-axis) and sunspot numbers (y-axis).

REFLECT: At this point, the teacher should call on several students to report their observations. After discussing the observations, tell them that the pattern they see is called the Solar Cycle. Solar cycles have been numbered beginning with the minimum that occurred about 1755. A cycle includes an increase and the following decrease in sunspot numbers. Cycle number 22 peaked in 1990. The next two sunspot cycles are numbered 23 and 24. Students are to number the cycles on their graphs. Point out to students that during the Maunder Minimum (from 1645 to 1715), the solar cycle almost disappeared as no sunspots were seen. The link between climate (long-term variations in the weather) and sunspots may have something to do with the maximum number of sunspots in a cycle, but scientists do not completely understand the connection.

APPLY: Students use their graphs to answer various questions and predict aspects of the next sunspot cycle.

Options for modifying this activity:

As it is written, the activity for plotting sunspot numbers takes a class of 30 students, who meet in 45 minute periods, about three or four days to complete. To reduce the amount of time that you spend on the activity to about two days, you might try the following suggestions

• Have the students only plot every other point.

• Assign students to finish plotting the data as homework.

• For smaller classes (fifteen or less) and for an activity that gets students out of their seats and moving about, you might try the following procedure: 2 Teacher Guide, Activity 2: Sunspot Number Variations © Space Science Institute, 1999. All Rights Reserved. Use butcher paper long enough to graph the accompanying data (perhaps cover one wall of a classroom).

1. Prepare the butcher paper in advance by drawing the horizontal axis along the bottom and labeling it “Time in Years.” Number from 1700 to present. Draw a vertical axis on the left hand side of the butcher paper and label it “Sunspot Numbers.” Number from 1 to 200. Write a title.

2. Cut out the individual dates or series of dates for individual students to graph.

3. Have students graph the sunspot numbers that you have prepared. (This is most exciting when students have sunspot numbers that are not sequentially, but randomly dated so that they must move around to find the dates on the horizontal axis.) When all of the points are plotted, have several students connect the data points.

4. Ask students to observe the resulting pattern, answer the questions that accompany this activity, then draw their prediction for the next two sunspot cycles on the graph using a dashed ------line.

Explore More: To add an interdisciplinary or a personal touch, ask students to mark historical events or dates of personal interest such as birthdays.

3 Teacher Guide, Activity 2: Sunspot Number Variations © Space Science Institute, 1999. All Rights Reserved. r e o o h s f t l f a s r o t e l u l w b a s " y n s , r a e 3 . e " o e 6 v d v n i s n i t t e o n a i s d . t e v g u a s d o l i n e u r i n c t u e h n n t t i i q S i s r c n n t o u n g a i o . t b o n i i 4 s a i , t a r t e 2 n s c e r i o d e a l s a l d e d c r u d c i l i p n e s e y w c r a v x r c s w n p e o d n i s 3 t r a n a e e n , 2 o p l l a s a p e t b b s V n s t s r k o a a o n e n o s n n n i u t e r b h a o o s t s s t d s s e m e e r r u a a n t u u o e e o o b r r n f f q d S w o m s n r t r r o u n o u e u i t b o o b i 4 s a e , t e a y e e N 2 l a n m s h c h e t r i d e a b t u l s d s l d e d a r u s d r t c n e r d l i p n e e e n o y w c a c o r a v x e o f o o c s f l u w n p e e o s d n i l s c 3 t o r d n s . p a t a e e t b n , y 2 o p o o e l n l 4 s s i a r a a c p r e t t b o b s 2 u n s h p n i . t s t r a o a a t t o n r n o n o e n o o d i n n n n i c p e s y u t e i b h h p n a a o o u u a s t s t s l s w d a d p r s s e o m e e n s p n e r r a u a a r o r S t r u u o r 3 o n x u e e f o o r p r n f f e q c d g 2 G a a S s : m 2 s o r _ o e e r _ y h t b t _ e t o e ) o l a m i _ n s h n " b t u i l s s s _ i a r s 3 v a n a e r _ l e e n i t " c o p e s _ o o ) u t f l u w i x s _ d b a s c " d c e s . a _ e t n , y o 2 e n s 4 r s a r a c _ o r . e o " 2 e t A n h p s i _ t t t v t r h n o n o d _ e a i t i e c p e l t e i h i p n a _ r u ; b s t s s w d a d p t h _ o a e n e s n e o a u r c n _ t r n u r 3 o n v u f e a _ p u q c g 2 G a S s e d i _ t c u h _ n t i c _ s e r a r _ d r e _ e u p b w _ t p s . u s _ u n h o t t y _ f a p r o i o p _ a r R g n n r o t _ o f c g s e _ d i e i e . g _ a t e s m o d t _ a n n d e n e t l p _ o o i c i n a i p _ m c u t e o r e i u _ s d d t l g k o e r _ o u o a ( r a t a r u _ o c t p p q G S _ g M n _ ( S e _ : t _ t m E _ n s o S s e _ p e U s d s m : d s s n e n a D s n u a A s s e g m E a s s g n n l a n s T s a i n f o o s n N S i i i r r A u o t t g g c o t ) ) e E e d i c c s s n n i n p u t i i b h i i ( ( G w e v u s d d d i p k k k k s d G o m e s s o e e a d a a n u r r r r u u r a a U t n p p I A m m n P q T01234 T01234 g G S S

Problem: What pattern(s) emerge when sunspot numbers are plotted over a period of time?

Introduction

A student’s dream comes true! On a quiet, mild, mid-afternoon, the overhead lights flicker just a little. A few minutes later, the same lights dim faintly, then suddenly all is dark. A hoot of delight reverberates throughout the school as students’ hopes for an unexpected vacation rise. What happened to cause this sudden surprise?

If you live in the north, perhaps it was due to a sudden snowfall or sleet storm. If you live in the south, maybe it was a power overload on a hot day. But, this is a mild, quiet afternoon. What could cause a dramatic power outage? Just a few short decades ago we would never have suspected that our ultimate energy source, the Sun, was the culprit! How could that be?

That reliable sphere of glowing gas that rises daily in the east and sets in the west sends us visible light that arrives on Earth after about 8 minutes of travel through space. Be- sides its dazzling brightness, the Sun’s next most obvious features are the appearance of dark, cool areas called sunspots that can be seen when the Sun’s image is projected onto a piece of white cardboard through a pin-hole (never look at the Sun directly!!). Sunspots are huge magnetic field bundles that are shaped somewhat like a horseshoe magnet. These magnetic fields result in cooler, darker regions on the surface of the Sun that we see as sunspots. Sunspots are sources of a tremendous amount of energy including solar flares, the most violent events in the solar system. In a matter of minutes, a large flare releases a million times more energy than the largest earthquake.

Sunspots and the resulting solar flares affect us, here on Earth. In fact, the more we learn about sunspots and solar flares, the greater their influence on Earth appears to be. Solar flares emit radiation that includes X- rays and ultraviolet rays, and charged particles called protons and electrons. This radiation surge may damage Auroral curtains photographed by astronauts on electrical power systems, NASA’s STS-39 mission (courtesy of NASA) interfere with telecommunications, disrupt high-tech ship navigation systems, harm an astronaut in space, or create the spectacular aurora (Northern and Southern lights).

1 Student Guide, Activity 2: Sunspot Number Variations © Space Science Institute, 1999. All Rights Reserved. Currently, scientists at NOAA’s Space Environment Center in Boulder, Colorado, conduct research in space physics and develop new techniques for forecasting solar events like solar flares. The Space Environment Services Center is the national and world warning center for these disturbances, called space weather. Space weather affects both people and equipment not only in airline and space travel, but also in Earth-based jobs such as long-line telephone communication systems, pipeline operations, and electric power distribution.

Space Environment Forecast Center (courtesy of the Space Environment Center, NOAA)

Through years of study, we now know that the chances of a sudden surge in radiation on Earth caused by a solar flare is related to an increase in the number and complexity of sunspots. Therefore, researchers plot average sunspot numbers over a period of time so that we know when to expect the next series of disruptive, potentially dangerous solar flares. The sunspot number (also called the Wolf number after Rudolph Wolf, who devised the method) is not actually the number of sunspots on the Sun. It is calculated with a formula that does depend on the number of visible sunspots recorded at selected observatories around the world. Another mysterious connection between sunspots and life on Earth has to do with climate. During a period from 1645 to 1715 known as the Maunder minimum, almost no sunspots were seen. During that same time, Earth’s Northern Hemisphere experienced the “Little Ice Age” as average temperatures dipped and rivers froze. What is the connection? Scientists are not certain, but sunspots must be telling us something important about how the Sun works and produces energy.

Thus, as our knowledge of the interaction Europe experienced a Little Ice Age in the between the Sun and Earth improves and our seventeenth century. This painting, Skating/ use of the space environment increases, space Frozen River, recorded by Hendrick Avercamp is weather forecasting becomes more important. of an unusual freezing of Dutch canals. Although we may feel, see, or hear nothing unusual, our electrical power may fail, our telecommunications may falter, and satellites may no longer function. Some people may speak of mysterious, superstitious forces, but we know that none other than our closest star, the Sun, is the culprit. And in the long term, studying sunspots could help us solve the many mysteries of our nearest star — mysteries that could mean life or death for planet Earth. 2 Student Guide, Activity 2: Sunspot Number Variations © Space Science Institute, 1999. All Rights Reserved. ACTIVITY 2 STUDENT WORKSHEET Procedure:

1. Working in groups of three, read the text for this activity.

XXXXXXXXXXX 2. When all of you are done reading the text, obtain three sheets of graph paper (one for XXXXXXXXXXX each of you), colored pencils and a ruler from your teacher. Each of you will now com- XXXXXXXXXX plete a graph.

NOTE: Be sure to agree beforehand on what scale you will use (for example, each vertical line might represent 1 year), because you will be taping these together once all graphs have been completed.

• Use your ruler to Draw a horizontal line (x-axis) along the bottom and label it “Time in Years.” One student will number his or her graph from the year 1700 to the year 1799. Another will label the second graph from 1800 to 1899. The third student will number the third graph from 1900 to 2020.

• Draw a vertical line (y-axis) along the left hand side of the paper and label it “Sun- spot Numbers.” Counting by tens, number from 0-200 sunspots. (Do not skip lines.) Again, be sure that all three of you use the same scale.

3. Plot the number of sunspots for each year using Charts #1 and #2. Connect the data points with a continuous solid line. Observe the resulting pattern in your graph and record your ideas in the space provided.

4. When each of you completes the graph, tape together the three graphs (put the tape on the back of the paper) so that the graph represents a time line from 1700 to 2020.

NOTE: Tape your graph together so that the time line is continuous, i.e. with no breaks. One or more of you may need to cut off the part of the edge(s) of your graph in order to accomplish this.

3 Student Guide, Activity 2: Sunspot Number Variations © Space Science Institute, 1999. All Rights Reserved. Discuss the pattern with your group and record your ideas in the space provided, along with a sketch of your group’s graph. Be prepared to share your ideas with the class.

Sketch

NOTE: Sunspot cycles have been numbered beginning with the minimum that occurred about 1755. A cycle includes an increase and the following decrease in sunspot numbers. Cycle number 22 peaked in 1990. The next two sunspot cycles are numbered 23 and 24.

5. Beginning with the sunspot maximum about year 1761, number each sunspot maximum directly above the line graph.

6. Using a dashed line ------, draw your prediction for the next two sunspot cycles on the graph (i.e. cycles 23 and 24).

7. In the space provided, compare what you now know about sunspots and their variation to what you knew when you started this activity.

8. What pattern(s) emerge when sunspot numbers are plotted over a period of time?

1. What is the average time between the high points (periods of maximum sunspot activity)?

2. Predict the years for the next two sunspot maxima (sunspot cycle numbers 23 and 24). Show your work.

3. Predict the years for the next two sunspot minima.

4. Predict how many sunspots there will be in the year that you graduate from high school.

5. What additional patterns do you see when you observe data over a long period of time compared to observing data for the shorter period of time? (For example, compare the individual graph that you made for the 100 year time period to the larger graph.)

6. Why is it important to collect and to study data over a long period of time before drawing conclusions? Give an example other than sunspot data.

7. Explain (tell why you came up with) your prediction for the years of sunspot maxima (cycle numbers 23 and 24).

8. Predict how large sunspot cycle numbers 23 and 24 will be. Explain your prediction.

9. Predict the “shape” (on the graph) of the next sunspot cycle (23). Explain your prediction.

6 Student Guide, Activity 2: Sunspot Number Variations © Space Science Institute, 1999. All Rights Reserved. Sunspot Chart #1: 1700 - 1850 Sunspot Sunspot Sunspot Sunspot Year Year Year Year Number Number Number Number 15700 1173 81M1 17m377 5 1281 12. 11701 191173 160 1877 149. 1981 13. 16702 101374 771577 952. 1481 35. 13703 211074 481477 1M654. 1881 4M5. 16704 321074 291977 1725. 1181 41. 18705 5M1674 3101878 884. 1181 30. 19706 2415m174 1178 698. 1981 23. 10707 251174 121578 308. 1682 15. 10708 161274 231878 212. 1682 6. 18709 1074 7441278 1m0. 1482 2 13710 174 860 11785 234. 1882 1m. 10711 1974 9860. 1978 842. 1582 8. 10m0712 1475 873. M 1278 1M3 1682 516. 12713 1775 1487. 1978 1630. 1382 36. 11714 121875 497. 1178 1718. 1682 49. 17715 231775 300. 1979 889. 1282 64. 17716 44175 12.2 16791 696. 1782 6 13717 6M175 59.6 m 10792 601983 7M0. 10718 661275 130. 1979 416. 1883 47. 19719 371475 342. 1179 421583 27. 18720 28175 47.6 13795 231. 1583 8m. 16721 29175 54 16796 141283 13. 12722 201976 672. 1479 65. 1983 56. 11723 1m1976 1885. M 1179 4m. 1583 6121. 11724 221276 691. 1879 67. 1383 1M38. 10725 431176 405. 1580 184. 1283 103. 18726 741476 316. 1480 391783 85. 12727 1M2 1976 5220. 1580 401684 64. 13728 160 1476 131. m 1180 413. 1784 36. 13729 771876 347. 1580 4M7. 1284 224. 17730 48176 69.8 12805 432. 1784 1m0. 15731 391176 1606. M 1180 248. 1584 1 11732 10177 100.8 11807 150. 1184 40. 15m1733 1677 881. 1180 86. 1584 61. 16734 121577 696. 1580 27. 1584 98. 14735 331877 304. 10m881 1784 1M24.

10736 71 1774 30.6 1481 19. 1384 96. 11737 821581 1685 066.

7 Student Guide, Activity 2: Sunspot Number Variations © Space Science Institute, 1999. All Rights Reserved. Sunspot Chart #2: 1851 - 1995 Sunspot Sunspot Sunspot Sunspot Year Year Year Year Number Number Number Number 15851 684. 1888 64. 1792 106. 1396 112. 11852 594. 1388 6m. 1392 5414. 1996 53. 19853 301189 76. 1992 623. 1696 37. 16854 210. 1689 375. 1992 631996 27. 17855 62. 1389 781892 7M7. 1296 41m0. 13856 4m. 1189 38M5. 1992 9654. 1196 15. 17857 242. 1889 701793 365. 1796 4 18858 554. 1489 611293 271. 1896 93. 18859 963. 1889 421. 1193 181. 1996 1M05. 18860 9M5. 1289 7236. 1793 5m. 1596 9105. 12861 787. 1789 246. 1793 80. 1597 104. 11862 599. 1189 152. 1193 316. 1697 66. 14863 401590 96. 1793 729. 1997 68. 17864 411790 2m. 1493 71M314. 1897 3 15865 320. 1590 1693 81409. 1597 34. 13866 136. 1490 294. 1893 858. 1597 15. 13867 7m. 1290 4401894 667. 1697 1m2. 16868 357. 1590 6M3. 1594 1477. 1597 27. 14869 761890 523. 1694 380. 1597 92. 19870 1M3 1290 7631394 196. 1497 1M55. 12871 1811. 1590 448. 1694 9m. 1698 0154. 16872 1901. 1990 453. 1294 313. 1498 140. 12873 606. 1691 168. 1694 922. 1998 115. 17874 414. 1791 57. 1694 1M351. 1698 66. 17875 121691 38. 1394 1436. 1998 45. 13876 131. 1491 1m. 1794 91534. 1998 17. 14877 142. 1691 90. 1995 863. 1498 1m3. 14878 3m. 1491 5417. 1495 679. 1498 29. 16879 1191 6527. 1595 381. 1298 100. 13880 372. 1991 1M303. 1995 193. 1698 1M57. 13881 584. 1691 840. 1495 4m. 1699 0142. 17882 599. 1691 653. 1895 311799 145. 17883 6M3. 1692 0367. 1795 1241. 1399 99. 15884 613. 1192 276. 1295 1M390. 1699 54. 12885 522. 1292 184. 1895 1484. 1999 2 14886 235. 1892 5m. 1995 9155 1599 19. 11887 13. Each "M" marks a sunspot cycle maximum and each "m" is a minimum. Through 1944, yearly means were calculated as the average of the 12 monthly means; since 1945, yearly means have been calculated as the average of the daily means.

Saturn and its Moons

Its orbit around the Sun

Other factors affecting density and mass Guide to Teachers

QQQQ¢¢¢¢

QQQQ¢¢¢¢ Goal: Students will learn how to determine the rate of rotation and the period of rotation for a sphere with identifiable surface features.

In this activity, students will better understand the concept of rotation by learning how to determine the period of rotation and how to calculate rotation rates, which they will apply to the Sun in the next lesson. It functions as an EXPLORE phase in Solarscapes.

Note: This activity uses a phonograph record turntable with adjustable speeds (at least down to 33-1/3 RPM) and a featureless styrofoam sphere (at least 6” in diameter, although the bigger the better). If a suitable sized sphere is not available, a cylinder such as a large roll of paper towels can be substituted. If none of these materials are available, a rotating globe can be used in place of the turntable and sphere. The teacher can simply turn the globe to provide the rotational motion. The turntable and sphere (or globe) should be strategically placed in the classroom so that all students are within good viewing distance.

MATERIALS NEEDED

1 23 99 3 81 9 10 92 38 019 238 20 3 94 85 28 40 5 582 90 59

Q¢

• The student activity, “Determining the Rotation Rate of an Object” (included) • A photocopy of the student activity, “Determining the Rotation Rate of an Object,” - preferably one copy per student • Turntable and styrofoam sphere • Colored circular stickers to mark the globe

XXXXXXXXXXX DISCUSS: Point out to the class that astronomers have to make observations of distant XXXXXXXXXXX celestial objects from Earth (or from orbit above the atmosphere). They cannot travel to XXXXXXXXXX those objects and experience them first hand. Ask the class what sort of observations of these distant objects can be made using only telescopes. (Answers may include information about an object’s features, its motion and its spectrum.)

Place the styrofoam sphere on the turntable (set at low speed) and ask students to make observations. After several minutes, ask students if it may help to place one or more colored dots on the rotating sphere. Instruct students to now write their ideas for how they might determine the rate of rotation for the sphere. Have them discuss in their answers why the dots may help.

Instruct the students to break into groups of 3 and to discuss their answers before moving on.

REFLECT: In groups of 3, students are to share their ideas and determine a best procedure for finding the object’s period of rotation. They are to record a step-by-step procedure. In a class discussion have groups compare their answers and their methods. Stu- dents can make adjustments to their methods if they hear good ideas which they had not thought of.

APPLY: Discuss with students how you might apply this method to finding the rotation rates of heavenly bodies. Talk about the moon and that we always see its same face. What does that imply about its rotation? As an assignment, students are to find a picture of a planet (e.g. Jupiter) or other celestial body and identify a feature that could be used to determine its rate of rotation and answer other questions.

As a lead-in to the next activity, you might ask students how the fact that Earth is revolv- ing around the Sun will complicate calculations if we are trying to determine the Sun’s period of rotation. Students can actually orbit the rotating sphere (‘the Sun”) in the classroom and determine how their observations change.

1. To find the period of rotation, locate a distinguishing feature on the globe. As the globe spins on its axis, time (in Earth hours) how long it takes for the feature to reappear. This is its rotational period. To find the rate of rotation, divide the number of times the feature reappears by the time in Earth hours.

2. Answers will vary. A sample of possibile answers is given in the table below.

Deefinition Exampl

Rotation The spin of an object about Earth, Jupiter, Sun, artificial satellites. its axis.

Rate of How fast an object spins. Jupiter spins (rotates) much faster than Rotation Earth.

Period of The time it takes an object Jupiter's period of rotation is much Rotation to complete one full rotation. shorter than Earth's.

3. Yes, estimating the rate of rotation would be difficult if there were no visible features that were permanent enough to count as the planet rotates on it's axis. (Some objects, not planets, may spin so reapidly that it is impossible to observe a feature.)

3 Teacher Guide, Activity 3: Determining the Rate of Rotation and Period of Rotation © Space Science Institute, 1999. All Rights Reserved. n i f s o n y l l l o t i a . c t s e e s r e d e r i u o o u q d c g s t t d r n n e n e . e a a w d d i , s u r u t 3 n t e # t a S s i r c n d o , g e i o n e t e a t d n n n r a e d h i i a e t s r u t n . o s o e t e o m o t a s o t i s t u a r l d r c r a n t i y d e e e p s r e l e t l f o v e n w t i a e b b a w t d o n n c u o a t i d r a s s e n o o h f d i e r p s n l s a o s o t m y r . s e a u i l u r t a i o d t d k n t q e e f o n i R c d c p t s r o i e o c e t r i a e e a n u r u , h l l t d r e t t t n f a d e o r p p u c t e a e e h r , t i n t o p x o a h h o d t p r t t t m i i c e o G a S w : o d 3 . n r t d o o i o u , e t i i n t e a y t o d n o t r a e e i r a t e y s l d o u t n s i e d t e e b m n a o t d u a r o n l d a r v a t i d e s e u P p r i e t t f a v e e o t e b o a w o n n o s a o i d r n c o d o d t f d i p s y l h s o t m t y l . e n i u l u r t A a i u p d t n t e e o f o n i a b c p t p r o i o c e y t a e e a r u r u , h l d r t t t n r d e o r p n u o c t e a e e d r o t i i o x a f f h h o d o p r t t t m i c e d G S i m c t i e o y d a o f d n _ o , e r t d i i n r t t n l _ t n a e e i u u b _ n m o ) s o l n r e o o _ e s e b m " a t u e l s c d _ r l t d a R 3 i a a i e _ t e p r . y t t " t v R l a s _ d e ) f e o i a o t o n p h _ a " d r n t a n o o o p f _ e r g t i 2 p s r a s o t e _ y s . i e " l t e r a n d n e t _ d e t t e v n h u i e o o o _ c p r o a t t t e o i e s i e d n t _ u r u a r h ; d s r u a t t a t e h _ o t r e t u c e e d o f r c n _ t e i u i o v o h e R a c _ b b p r t m c d G a S e d i _ t S u h _ g n t c _ s e a n _ d r . i _ e u k p _ t s p n u t s _ a i o t t o y _ f r i o n p _ e g m n o t _ h . d t f c e i _ r e i d t i d _ e e e m a t t d _ t n t e p l e _ i n l o p a e c _ e m p i u o e _ d t l o g r k m D _ u r a ( t a a o _ o t p c G S _ g M n _ ( e _ : e t _ m E r e _ n s S u s e _ h t t e U o c s m : t i s s g e e e d D s p t t A n e n g m E i a a m s , l e a a r r g n T t s n e a i n i n N e S s i h A u i n n y t t n ) ) e E f m d d o o s s i r m i n p a r i i i t ( ( G g r l t t e v u e u v i k k n t e n t p d a a G o t s s i o t t d e a e u r r s e f a a t U o o n e d r r u P i D I f d T01234 T01234 o G S S

4 Teacher Guide, Activity 3: Determining the Rate of Rotation and Period of Rotation © Space Science Institute, 1999. All Rights Reserved. Student Guide to Activity 3: Determining the Rate of Rotation and the Period of Rotation for an Object.

Problem: How can we determine the rate (speed) of rotation and the period of rotation for a sphere with identifiable surface features?

Introduction

In ancient times the idea of a spinning (rotating) Earth was considered quite absurd. People may have asked: “If the Earth were indeed spinning like a top, why do we not feel this motion? Why do things including us not go flying off of the planet?” (How would you answer these questions?)

Today we know that the heavens are filled with spherical objects that orbit other celestial bodies (revolve) and spin about an axis (rotate). Astronomers have discovered these motions not by taking fantastic space voyages, flying through the Cosmos or visiting strange planets. Rather, they have reached their conclusions by observing distant objects through telescopes.

We can simulate their discoveries on a small scale by observing a rotating object in the classroom. Because astronomers are not able to actually visit the objects that they observe, you too will need to view the rotating object from a remote location. This means that all observations for your model must be made from your lab table or desk. Your task will be to observe the rotating object, making both qualitative (without numbers) and quantitative (with numbers) statements about its motion.

The McMath solar telescope at the Kitt Peak Solar Observatory (courtesy of the National Optical Astronomy Observatories) 1 Student Guide, Activity 3: Determining the Rate of Rotation and Period of Rotation © Space Science Institute, 1999. All Rights Reserved. ACTIVITY 3 STUDENT WORKSHEET Procedure:

XXXXXXXXXXX 1. Use the model to observe as many characteristics of rotation as possible. Include both XXXXXXXXXXX your qualitative and quantative observations. XXXXXXXXXX

Characteristics of Rotation

2. Use your knowledge of astronomy or familiar objects on Earth to write a definition and give an example of the following three terms: Rotation, Rate of Rotation and Period of Rotation.

Deefinition Exampl

Rotation

Rate of Rotation

Period of Rotation

2 Student Guide, Activity 3: Determining the Rate of Rotation and Period of Rotation © Space Science Institute, 1999. All Rights Reserved. 3. Working individually, observe the rotating object in your model. Determine the rate of rotation and write your answer in the space below. Include several sentences that describe your method.

4. With a group of two other students, compare your answers and your methods. Are all of the answers the same? If not, why?

5. With your group, determine a method to find the object’s period of rotation. Record your step-by-step procedure below. Then use your procedure to actually calculate the object’s period of rotation. Be prepared to share your results with the class. Your Step-by-Step Procedure Your Actual Calculation

Find a picture of a planet or other celestial object. Make a copy or drawing of it. Answer the questions below:

1. Explain how you could estimate its rate of rotation or period of rotation. (Hint: Does the object have a distinguishing feature that may be helpful?)

2. What is the officially reported period of rotation?

3. Are there any objects for which estimating the rate of rotation would be difficult? (Explain your answer.)

Saturn and its Moons

Its orbit around the Sun

Other factors affecting density and mass Guide to Teachers

QQQQ¢¢¢¢

QQQQ¢¢¢¢ Goal: Students will determine the Sun’s period of rotation.

In this activity students apply the previous lesson to the Sun, calculate its period of rotation, and reflect on what they have learned about the Sun compared to what they originally knew about the Sun at the start of Solarscapes. It functions as a REFLECT/APPLY phase in Solarscapes.

MATERIALS NEEDED

1 23 99 3 81 9 10 92 38 019 238 20 3 94 85 28 40 5 582 90 59

• One copy of the student activity, “The Sun’s Period of Rotation” (included) • An overlay to determine solar latitude and longitude (Figure 4, included) • Photographs of sunspots for four consecutive days (Figure 5, included) • A photocopy of the student activity and Figures 4 and 5, preferably one copy per student • A calculator

XXXXXXXXXXX DISCUSS: Open a class discussion by asking students to recall what they know about XXXXXXXXXXX sunspots. Make a list of the information students provide. Now ask your students to XXXXXXXXXX recall how they can determine the period of rotation of an object with fixed features on its surface and discuss this procedure. Tell them (if they have not already pointed this out themselves) that sunspots appear to move across the face of the Sun over time. Have the students form groups of 4. They are to list all of the possible reasons that might be responsible for that apparent motion then share their list with the class. Four common reasons that one might expect are:

• Sunspots move across a non-rotating Sun. • The Sun rotates. • The Earth moves around the Sun, causing sunspots to appear to move. • Sunspots appear and disappear in different places, appearing to move.

Ask students to think about these explanations and to try to devise ways in which one could distinguish among the possibilities.

EXPLORE: Hand out the worksheets to the students, who will work in groups of three to calculate the solar rotation period. Students are to answer the questions individually as homework.

REFLECT: Student groups report their calculated periods of rotation. The Sunspot Motion Table is shown on page 3. It displays the measurements and calculations which should approximate those of your students. If one (or more) groups ended up with significantly incorrect results (the correct answer is about 26 days), ask them to go back and review their measurementts and/or calculations. Discuss any remaining discrepan- cies between the answers with the students. Did they use the same sunspot groups? Did anyone forget to correct for Earth’s orbital motion? Point out that measurement uncer- tainties as well as other factors (in this case the exact feature chosen) can influence the answer. Scientists often get different results, then try to figure out what is causing those differences.

APPLY: Ask students to discuss in their groups what they know about the Sun. Review the brainstorming list developed at the start of Solarscapes.

Change in Corrected Period of Longitude of Longitude Longitude Rotation Sunspot Group (Ex: Day 2 - Day 1) Change (Solve for "X")

D9ay 1 2 0

D8ay 2 1 0 110 120 30 days

D3ay 3 0 150 160 22.5 days

D0ay 4 -1 0 130 140 25.7 days

A2verage Rotational Period = 78. days = 26 Days 3

NOTE: Each horizontal and vertical line on the overlay (Figure 4) represents 100 latitude or longitude, respectively. Since these lines do not show tenths of a degree, students should estimate the longitude to the nearest whole degree, then solve for “X” to the nearest tenth of a day.

3 Teacher Guide, Activity 4: Rotation Period of the Sun © Space Science Institute, 1999. All Rights Reserved. . a i r e t i r c n s . g e n u n d y o s i i l i S e r t t u n s c n o i i e e G c e r u d s t m r q r o n o h i e d e c r e t t n d e e h d a t u p d t f n s t k a n S r o n s o e e i p e a t t h u w d a t d s t o u n t r n o n o r i g a S w i o r r e u t o . s n e P s r y d e n e e i n o d n i i d i o u w n r m t t d s r d e m S o a n e e r o p t l i i a e r n e t b o n t i e t d e a d o p s i d n a s t y u n a i l t t a n o t . o t , n o i c p e y o o i t p e e t u r d s u d r r i a o e r t o u e R o u r t u r o o f h r t q c g G G S : m 4 o _ o y r _ o t . e t s i _ d ) o n e e i _ n s o n v l " i i l i _ i r b m 2 a r _ d e a t m " e r o s _ p t ) t i i c e _ r e o a t " n e _ d e e n 2 o s r A p i d _ s t e " y e i _ l t a n v t h t . n r _ a t o e c p o i p e i _ e t u r ; o s u d r t h _ a o r e f t o u e r c n _ t r o v o h e a _ r t c g G S e c d i _ t i u h _ n t c r _ s e a _ d r b _ e u p . _ t u p k u s _ s o t y _ a f R r t i t o p _ g o n o t e _ n f c g e h . _ d i t i e _ d t e n m i d t e _ a n i t d e t l p _ e o i n l r a p _ m c e p o e i u _ o d t l g k o r m _ u a ( r c a t a o _ o t p c G S _ S g M n _ ( e _ : t _ m E e _ n s S s e _ h t e U s m : s s g g e D s A n n e m E i i s s g l a T s n n a n n i i N S i A u o m r t ) ) i E m m d e t e s s i n p r r l ( ( G s e v u e e b w i k k e t t d G o s s s o d e e u u r r a a U t n n p Sun's period of rotation the Sun's period of rotation and I D D T01234 T01234 G Q S S a

Problem: How can we determine the Sun’s period of rotation?

Introduction

You and your buddy are having a “camp out.” It’s 4:00 AM. You’ve awakened so many times that you’ve lost count. What was it this time? Was there some little sound, the tent flapping in the gentle breeze, or the purr of a cat, or maybe the snapping of a twig? You feel safe enough in your own back yard, snuggled warmly in your sleeping bag. You aren’t really scared, but you hear every tiny sound that never before seemed so loud; night seemed to drag on forever. Finally, the first hint of daylight appears as your eyelids grow heavy and your brain starts wondering, “What causes day and night?”

You might answer, “Earth’s rotation,” but you’ve heard others say, “Earth’s revolution.” Which response is correct? If you mean Earth’s spinning on its axis, then “rotation” is correct. As Earth rotates, the Sun comes into view at daybreak. Earth continues to spin, so that the Sun appears to move across the sky until it sets at night. The Sun is no longer visible, but Earth continues to rotate until the Sun comes into view the next morning. One complete rotation takes about 24 hours, or one day. In contrast, “revolution” means the motion of a body around a point in space or another body. Earth’s tilt on its axis and its revolution around the Sun give us seasons. After about 365 rotations, or one year, our Earth has revolved around the Sun one time.

We know from personal experience that Earth rotates because we experience day and night and we know that the Sun does not revolve around Earth. What about our Sun, that sphere of glowing gas rising just beyond the eastern horizon? Does it rotate? To find out, we can use one of the Sun’s most prominent features, sunspots.

Ancient Chinese, Japanese, and Greek literature refer to observations of spots on the Sun; however, the first recorded telescopic observations of sunspots were not made until 1610 by Galileo, an Italian astronomer. After many years of speculation, we are still not sure what causes sunspots, but we do know some interesting details about them.

Here, Christopher Scheiner, a contemporary of Galileo’s, and a fellow Jesuit scientist trace sunspots in Italy, in about 1625. 1 Student Guide, Activity 4: Rotation Period of the Sun © Space Science Institute, 1999. All Rights Reserved. A large sunspot can sometimes be 20 times larger than Earth (courtesy, Space Environment Center/NOAA)

Current theory says that sunspots are caused by horseshoe shaped magnetic fields, buried just below the Sun’s surface, that prevent the flow of hot gases from below. Like a horseshoe magnet, sunspots have both a magnetic north and south pole. The spot where the magnetic field is located cools slightly compared to its surroundings. Because the spot is cooler, it looks darker.

Sunspots occur in 11 year cycles where the sunspot number increases from a minimum of almost zero to a maximum of over 100 spots. After one 11 year cycle, the poles of the horseshoe shaped magnetic fields switch and another cycle begins. Consequently, we have an overall 22 year magnetic cycle as well as an 11 year sunspot cycle.

At the beginning of an 11 year cycle, several spots appear at about 30½ north and south latitudes. As the cycle progresses, you can track the sunspots’ motion. Generally, individual sunspots or groups of sunspots do not shift significantly in latitude over time. However, they do seem to move across the face of the Sun. What do you think could be the reason for this? Could we use this apparent motion to determine the Sun’s period of rotation?

1. Locate the major group of sunspots on the photographs in Figure 5.

2. Place the plastic overlay (Figure 4) on the photographs so that you can determine the latitude and longitude for the major sunspot group. Each vertical and horizontal line equals 100 latitude and longitude, respectively.

3. Estimate how far the sunspot group moves between day one and day two by subtract- ing the smaller longitude from the larger. Record this longitude change in the Table below. Estimate this number to the nearest whole degree.

4. Repeat the same process for the next days up to day four and record your results.

5. The Earth revolves around the Sun at a rate of 360 degrees in one year (365 days) or an average motion of about 10 per day. Since Earth revolves around the Sun in the same direction as the Sun rotates, our motion seems to chase after the sunspots. Thus, the apparent movement of sunspots is less than the real rotation by about 10 per day. Therefore, you must compensate for the orbital motion of Earth by adding 10 to your computed apparent daily motion.

6. Let us assume that sunspots are features whose position on the Sun does not change very much over the course of a solar rotation. Use the following proportion to calculate the Sun’s period of rotation (in days):

corrected longitude change = 360 degrees 1 day X days

7. Find the average rotational period and record it in the Table below. Calculate to the nearest tenth of a day. Be prepared to share your result with the class.

Sunspot Motion Table - For Student Use

Change in Corrected Period of Longitude of Longitude Longitude Rotation Sunspot Group (Ex: Day 2 - Day 1) Change (Solve for "X")

Day 1

Day 2

Day 3

Day 4

Average Rotational Period =

1. Since the sunspot group appears to move across the Sun’s surface, what kind of solar motion does this suggest?

2. Based on your calculations, what is the Sun’s average period of rotation?

3. If the sunspot group had changed latitude would you have been able to calculate the number of degrees of change per day as easily? Why or why not?

4. Answer the problem question at the beginning of this activity. Include in this discussion what you learned about the Sun and what more you would like to learn about the Sun.

Answer Key

Activity 1: Features of the Sun

No Question and Answer section.

Activity 2: Sunspot Number Variations

1. Approximately 11 years.

2. & 3. Answers will vary. Students should use the pattern made by their graphs, including the 11 year average variation between both the sunspot maximum and sunspot minimum, to predict the shape of future cycles. Add 11 years to the last minimum to predict the next minimum. Add 11 years to the last minimum to predict the next minimum; add 11 years to the last maximum to predict the next maximum. More sophisticated predictions take into account the shape of each cycle as well as long term trends.

4. Answers will vary.

5. Accept any reasonable answers. A. Number of sunspots in maxima seems to be increasing. B. Sharper rise than decline in the slope of most cycles. C. Spikes of rising sunspot numbers appear on the declining side of some cycles. D. An undulating pattern of sunspot maxima (pattern within a pattern). E. Double peaks. F. The number of sunspots in each maximum appears to be increasing. (Is this a pattern or a result of better data collecting techniques?)

6. Data over a short period may be a temporary anomaly. Example: Global Warming could be a relatively short term trend.

7. Answers will vary.

8. Students should use their graphs to determine the maximum number of sunspots for each cycle in their prediction.

9. Answers will vary.

2. Answers will vary.

Activity 4: The Sun’s Period of Rotation

1. Rotation

2. Answers will vary. Observations indicate that the Sun’s equatorial regions rotate around its axis every 25 days, while the areas around its poles may take as long as 33 days.

3. No, since the amount of time for the feature to reappear would change because of changes in latitude as well as in longitude.

4. Answers will vary. Students should summarize their procedure and discuss what more they would like to learn about the Sun.

THE SUN Prominence Chromosphere

Radiation Zone Sunspot

Convection Zone

Core

Granulation

Spicules

Photosphere

Coronal Hole High Speed Solar Wind Corona Figure 2

Visible Sun (Courtesy, Yohkoh Telescope)

Solar Eclipse (Courtesy, Steve Albers)

Extreme Ultraviolet (Courtesy, Naval Research Laboratory) Figure 3

H-alpha sun (Courtesy, NOAA/SEC)

Solar Flare (Courtesy, National Optical Astronomy Observatory)

0 300 30 200 200

100 100

00 00

-100 -100

-200 -200

-300 -300

NOTE: Each horizontal or vertical line = 100 latitude or longitude, respectively.

Instructions: Copy this onto transparencies for use with Figure 5. Figure 5. Sun Rotation Series

Day 1 Day 2

Day 3 Day 4 Sunspots can be used to determine how long it takes the Sun to rotate about its axis. These visible solar images were taken by the Japanese Yohkoh spacecraft, during February 12th through the 15th, 1996. © Space Science Institute, 1999. All Rights Reserved.