Awesome Light III: Teacher Packet

Compiled by:

Morehead State University Star Theatre

with help from Bethany DeMoss

Table of Contents

Table of Contents 1

Corresponding Standards 2

Vocabulary 4

Starry Night Activity Pack (Primary) 6

The Milky Way (Middle Grades) 17

The Universe: Big Bang Balloon (High School) 21

References 24

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Corresponding Standards: Awesome Light III

Next Generation Science Standards

5-ESS1-1.

Support an argument that differences in the apparent brightness of the sun compared

to other stars is due to their relative distances from Earth. [Assessment Boundary:

Assessment is limited to relative distances, not sizes, of stars. Assessment does not

include other factors that affect apparent brightness (such as stellar masses, age,

stage).]

06-ESS1-2.

Develop and use a model to describe the role of gravity in the motions within

galaxies and the solar system. [Clarification Statement: Emphasis for the model is

on gravity as the force that holds together the solar system and Milky Way galaxy

and controls orbital motions within them. Examples of models can be physical (such

as the analogy of distance along a football field or computer visualizations of

elliptical orbits) or conceptual (such as mathematical proportions relative to the size

of familiar objects such as their school or state).] [Assessment Boundary:

Assessment does not include Kepler’s Laws of orbital motion or the apparent

retrograde motion of the planets as viewed from Earth.]

06-ESS1-3.

Analyze and interpret data to determine scale properties of objects in the solar

system. [Clarification Statement: Emphasis is on the analysis of data from Earth-

based instruments, space-based telescopes, and spacecraft to determine similarities

and differences among solar system objects. Examples of scale properties include

the sizes of an object’s layers (such as crust and atmosphere), surface features (such

as volcanoes), and orbital radius. Examples of data include statistical information,

drawings and photographs, and models.] [Assessment Boundary: Assessment does

not include recalling facts about properties of the planets and other solar system

bodies.]

HS-ESS1-1.

Develop a model based on evidence to illustrate the life span of the sun and the role

of nuclear fusion in the sun’s core to release energy that eventually reaches Earth in

the form of radiation. [Clarification Statement: Emphasis is on the energy transfer

mechanisms that allow energy from nuclear fusion in the sun’s core to reach Earth.

Examples of evidence for the model include observations of the masses and

lifetimes of other stars, as well as the ways that the sun’s radiation varies due to

sudden solar flares (“space weather”), the 11-year sunspot cycle, and non-cyclic

variations over centuries.] [Assessment Boundary: Assessment does not include

details of the atomic and sub-atomic processes involved with the sun’s nuclear

fusion.]

HS-ESS1-2.

Construct an explanation of the Big Bang theory based on astronomical evidence of

light spectra, motion of distant galaxies, and composition of matter in the universe.

[Clarification Statement: Emphasis is on the astronomical evidence of the red shift

of light from galaxies as an indication that the universe is currently expanding, the

cosmic microwave background as the remnant radiation from the Big Bang, and the

observed composition of ordinary matter of the universe, primarily found in stars

and interstellar gases (from the spectra of electromagnetic radiation from stars),

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which matches that predicted by the Big Bang theory (3/4 hydrogen and 1/4

helium).]

HS-ESS1-3.

Communicate scientific ideas about the way stars, over their life cycle, produce

elements. [Clarification Statement: Emphasis is on the way nucleosynthesis, and

therefore the different elements created, varies as a function of the mass of a star and

the stage of its lifetime.] [Assessment Boundary: Details of the many different

nucleosynthesis pathways for stars of differing masses are not assessed.]

HS-ESS1-4.

Use mathematical or computational representations to predict the motion of orbiting

objects in the solar system. [Clarification Statement: Emphasis is on Newtonian

gravitational laws governing orbital motions, which apply to human-made satellites

as well as planets and moons.] [Assessment Boundary: Mathematical

representations for the gravitational attraction of bodies and Kepler’s Laws of orbital

motions should not deal with more than two bodies, nor involve calculus.]

KY Department of Education Social Studies Standards

S.S 2.17 (5th

)

Students interact effectively and work

cooperatively with the many ethnic and cultural

groups of our nation and world.

S.S 2.17 (6th

)

Students interact effectively and work

cooperatively with the many diverse ethnic and

cultural groups of our nation and world.

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Awesome Light III Vocabulary

Older

Vocabulary Words Definition

Satellite 1. object put into orbit around Earth or another planet in order to relay communications signals or transmit scientific data

Galactic Plane Plane passing through a galactic center

Telescopes instrument used for viewing distant astronomical objects

Star a self-luminous gaseous spherical celestial body of great mass which produces energy by means of nuclear fusion reactions

Mars 1. third smallest planet in the solar system and the fourth planet from the Sun.

Jupiter Fifth planet from the sun and largest planet in our solar system

Comet A group of small objects orbiting the sun that are composed of ice and dust, when a comet approaches close enough to the sun it can produce a long luminous tail

Gas Giants 1. a class of a large, low-density planets composed primarily of hydrogen, helium, methane, and ammonia in either gaseous or liquid state (Jupiter)

Universe all of space and everything in it including the galaxies, stars, planets, gases, and dust etc.

Supernova explosive end to a star’s life that occurs when the star is no longer in equilibrium, caused when gravitational forces in the star are overcome by interior pressure pushing outward

Binary System two stars that orbit a common center of mass, appearing as a single star when visible to the unaided eye

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Awesome Light III Vocabulary

Younger

Vocabulary Words Definition

Satellite 2. object put into orbit around Earth or another planet in order to communicate with Earth

Telescopes Tool used for viewing distant objects in the sky

Star point of light in the sky

Mars 1. third smallest planet in the solar system and the fourth planet from the Sun.

Jupiter Largest planet in the solar system

Comet object in the sky that is identified by its long luminous tail

Gas Giants 2. a large, low-density planet (Jupiter)

Supernova explosive end to a star’s life

Binary System two stars that are close together and appear as one star

Constellations group of stars that form a pattern in the sky

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Starry Night Activity Packet From: Starry Night Education

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Lesson Plan G2The Stars

Introduction

We see the stars as tiny points of light in the sky.They may all look the same but they are not. Theyrange in size, color, temperature, power, andlife spans.

In these hands-on and Starry Night computerexercises, your students will explore the natureof stars. They will see how different from oneanother individual stars can be. They willobserve a glowing body as it changes tempera-ture and color. Your students will plot someproperties of stars and learn how these differentproperties of stars are related to one anotherand to the mass of the star. They will learn thatthe apparent visual brightness of a star is not agood indicator of its distance. In Starry Nightthey will examine several different stars andthey will see how some stars end their lives.

Key Concepts

� Stars are born, evolve and die.� Stars have a life cycle that depends on the

initial mass of the star.� The composition and structure of stars

changes at different stages in their life cycle.� Stars in the Milky Way can be different from the

Sun in size, temperature, age and brightness.� The Sun is a main sequence star.� Stars can be described as having apparent

magnitude, absolute magnitude and luminosity.� Other planets orbit around other stars.� Elements heavier than lithium are created in

the cores of stars.

Materials Required

Activity Part One• Small lamp with a clear (not frosted) bulb• Electrical socket with a dimmer switch

(rheostat)

Activity Part Two• Student worksheets• Pens or pencils

Activity Part Three• 1 small flashlight• 1 large and bright flashlight• A room that can be darkened

Time Required

Hands-on Activity Part One: 10 minutesHands-on Activity Part Two: 30 minutesHands-on Activity Part Three: 10 minutesStarry Night Computer Exercise: 35-45 minutes

Conceptual Background

All stars form from cold clouds of hydrogen gasthat collapse under their own gravity. The centerof the cloud heats up from the resulting increasein pressure and friction. Eventually the heat andpressure are great enough to force hydrogennuclei to fuse together and form helium nuclei.This nuclear fusion process releases energy andthe star shines with its own light.

Stars are made of mostly hydrogen, which isthe most abundant element in the universe. Starsuse hydrogen as a building block to make heavierelements. As a star ages it fuses hydrogen intohelium, and later the helium will be fused intoa series of increasingly heavier elements. Asstars age and continue the fusion process, thepercentage of hydrogen in the stars decreasesand the percentage of other heavier elementsincreases. The heaviest elements are fused inthe most massive stars. This planet and all that itcontains, plus other planets in the solar systemand around other stars, comes from the star-for-mation process.

Most of the characteristics of a star are gov-erned by how much mass the star containswhen it first forms. Low mass stars survive forbillions of years. They burn their fuel slowlyand at low temperatures. They die a quiet deathand leave behind a small white dwarf star thatslowly cools into a black dwarf.

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High mass stars only survive for a few millionyears. They burn their fuel at extremely hightemperatures and rates. Big stars die in spectacularsupernova explosions. The supernova can leavebehind either a neutron star or a black hole.

Even in a telescope, stars are so far away thatthey look like tiny points of light. But stars comein a range of sizes, colors, temperatures, energyoutputs, and life spans. Most stars are small, dim,red, and cool. They are so small and dim thatwe can’t see them. When we look into the nightsky we see mostly the big, hot, and bright stars.

We think of the Sun as an average star. But ifwe look at all the stars in the Milky Way galaxy,we find that 90 per cent of them are smaller,dimmer and cooler than the Sun. So, althoughthe Sun fits in the middle of the range of stellarproperties, it is bigger, brighter and more powerfulthan most of the stars in our galaxy.

Activity Part One

Stars are hot, glowing objects. This activity is asimple demonstration that shows the relationshipbetween the temperature and color of anotherhot, glowing object. Our Earth-based experiencesoften give us the idea that blue is cool or cold,and red is hot, as in “red hot.” With stars, theopposite is true. It’s all a matter of scale.

1. Set up the lamp with the clear, unfrostedbulb so all the students can easily see it.

2. Plug the lamp into a rheostat or an electricaloutlet that is connected to a dimmerswitch.

3. Darken the room.

4. Turn on the lamp and dim it until it is justbarely on.

5. Ask the students to observe and note thecolor of the glowing filament in the bulb.

6. Slowly turn up the bulb so it gets brighterand brighter (hotter and hotter).

7. Have the students observe and note thechanging color of the glowing lamp filament.

Figure G2.1Set up to demonstrate the relationship between colorand temperature.

Activity Part OneDiscussion Questions

A. When the lamp is turned down very low,what color is the filament in the bulb?

B. When the lamp is turned on full power, isthe filament hotter or cooler than when it is turned down low?

C. What color is the filament when the lamp is turned on at full power?

D. What progression of colors did you observeas the lamp was turned from minimumpower up through full power?

E. At what power level did the lamp glowmost brightly? Why?

Many students think of something very hot asbeing “red hot.” They seldom think of blue asbeing a “hot” color. With the lamp turned downto a minimum, the filament glows a dim red

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Lamp with unfrosted bulb.

Rheostat(Dimmer switch)

ElectricalOutlet

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color. The filament glows because it is hot, but itcan get much hotter and glow much more brightly.

As the lamp is turned up the filament receivesmore power. It gets hotter and glows brighter.Its color progresses from dim red to orange toyellow to white. As it gets hotter it glowsbrighter. There is a relationship between thetemperature and the color of the glowing fila-ment. If the filament could be made to gloweven hotter, it would progress from white toblue in color. At even higher temperatures itwould glow with invisible ultraviolet light.

Most students have seen this color progressionfrom red through yellow to blue in the flame ofa propane torch or a propane camp stove. Thecool flame is red or orange and the hottestflame is blue. The same color progression holdstrue for the stars. The coolest stars at 3,000degrees Celsius glow red. The hottest stars havesurface temperatures in the tens of thousands ofdegrees and they glow with a fierce blue light.Such stars are extremely bright, powerful, andeasy to see from great distances. Much of theirradiation is in the form of energetic ultraviolet,X-ray and gamma radiation.

Activity Part Two

This is a graphing activity that shows the rela-tionship between color, temperature and massin stars. Table G2a Star Comparison Chartgives data for 12 stars.

Your students will use this data to make aHertzsprung-Russell (H-R) diagram that plotsstar color versus temperature. A clear relation-ship will emerge. Astronomers call this curveon the graph the main sequence. The mainsequence is where stars spend most of theirlifetimes. Main sequence stars are powered byhydrogen fusion.

As you examine the data in Table G2a, you willnotice a pattern that follows through, more orless, in descending order, for color, temperature,mass and power.

The students’ plots should look similar to theone shown in figure G2.2.

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Table G2a Star Comparison Chart

Star Color Temperature in Mass in terms Power in Radius in terms Distance in degrees Celsius of solar mass Suns of Solar Radii Light Years

Sun Yellow 5,700 1 1 1 8 light min.Proxima Centauri Red 2,300 0.1 Unknown Unknown 4Barnard’s Star Red 3,000 0.1 0.01 0.2 6Epsilon Eridani Orange 4,600 0.1 0.4 0.8 11Alpha Centauri Yellow 6,000 1 2 1.4 4Altair White 8,000 3 12 2 17Vega White 9,900 3 61 3.3 25Sirius White 10,000 3 27 2 8.6Rigel White 10,000 3 52,000 92 777Regulus White 11,000 8 221 4.3 78Hadar Blue 25,500 20 79,000 24 526Alnilam Blue 27,000 20 112,000 44 1,360

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1. Give each student a Hertzsprung-Russelldiagram worksheet.

2. Use the data from Table G2a to plot each of the 12 stars on the H-R diagram. Starcolor is on the horizontal axis and star temperature is on the vertical axis.

3. Label each star’s data point with the nameof the star.

4. Draw a curve as best you can that joins thedata points smoothly.

5. On the outer vertical axis labeled “Mass in Solar Masses” mark the value of eachstar’s mass in terms of solar mass.

Activity Part TwoDiscussion QuestionsA. Is there a relationship between the color and

temperature of a star?

B. What is the relationship between color andtemperature?

C. Generally speaking, are the most massivestars also the hottest?

D. Look carefully at the data in table G2a. Canyou see a relationship between power, colorand temperature?

E. Where does the Sun fit into the pattern?

Stars come in different sizes and they producedifferent amounts of energy. The energy a starproduces is related to its temperature and color.White and blue stars burn their fuel at the highesttemperatures. They produce the most energy,and are the most powerful and most luminousstars. These stars are also the most massive stars.

Mass is everything to a star. More mass meansmore self-gravity so the star presses in on itselfmore strongly. This means it gets hotter in thecore than a smaller star, so it burns faster and at a much higher temperature. Because it burnshotter it also gives off more energy than asmaller, cooler star.

The Sun fits in the middle of the range of stellarproperties. It is a yellow star. Compared to otherstars, it is neither very hot nor very cool. It isneither very massive nor very powerful. Becauseof this we think of the Sun as an average star.

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Blue White Yellow Orange Red

AlnilamHadar

RegulusSirius

AltairRigelVega

SunAlpha Centauri

Epsilon EridaniBarnard’s Star

Proxima Centauri0

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Figure G2.2 Your students’ star plots should look similar to this illustration.

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Activity Part Three

The thing we notice first about stars is thatsome are brighter or dimmer. It looks as thoughthe brighter ones are closer to us and the dimmerones are further away from us. We have justlearned that stars vary a lot in the energy, andtherefore the amount of light, they produce.

This is a simple demonstration activity to provethat the apparent brightness of a star cannot beused to judge its distance.

1. Place the small flashlight on a desk or tablenear the front of the room.

2. Place the large flashlight on a desk or tablenear the back of the room.

3. Have the students gather at the front of theroom so they can all see both flashlightseasily.

4. Turn on both flashlights.

5. Darken the room.

6. Observe and compare the apparent brightness of the two flashlights.

7. Move the two flashlights back and forthuntil they both appear to have the samebrightness.

Activity Part ThreeDiscussion Questions

A. If you didn’t know which flashlight waswhich, would you be able to tell which oneproduced the most light?

B. From this exercise, and the data in tableG2a, what conclusion can you draw aboutthe stars Rigel and Sirius?

This is one of the most fundamental questionsabout the stars. Is it bright because it is close,or is it bright because it is intrinsically bright?This is why astronomers must know the dis-tance to a star. Without knowing the distance,it’s hard to get meaningful information aboutthe other properties of the star. Some stars lookbright because they are very near the Sun. Otherslook equally bright but are many times furtheraway from the Sun. These more distant stars areextraordinarily bright. Without knowing thedistance it’s impossible to distinguish betweenthe two.

The two flashlights can be compared to the starsSirius and Rigel. Sirius is about twice as brightas Rigel, but Rigel is almost 100 times furtheraway than Sirius. Sirius is about 27 times aspowerful as the Sun, but Rigel has the power ofmany thousands of Suns. Sirius looks very brightbecause it is close. If Rigel were as close as Siriusit would be blindingly bright.

Figure G2.3Two flashlights of different power placed at different distances can be used to demonstrate that apparent brightness is not a good indicator of distance.

Large Flashlight ObserverSmall Flashlight

Far from observer the large flashlight looks dimmer than small flashlight

Close to observer small flashlight looks brighter than the large flashlight.

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Starry Night Computer ExerciseLesson G2: The StarsEven a cursory examination of the night sky showsthat not all stars are the same -- some are brighter,some are fainter. A more careful inspection will showthat star colors are not the same. But the difference issubtle. Astronomers can deduce a lot of information aboutstars from their properties. This exercise examines someof these.

Teaching Strategies

Students should be aware that all values entered inthe database are approximate and subject to errors.Indeed, different sources will give different values formost of the parameters.

Colors are difficult to detect and have been exaggeratedin Starry Night. If a more realistic appearance is desired,see Using Starry Night in the Appendix of this binderon how to change color saturation.

Stellar evolution is a complex subject but studentsshould be able to understand that in general, hotbluish stars are young, yellowish stars are middle-agedand large reddish stars are near the end of their life.

Students might be interested in using the interactiveH-R diagram on other stars. The status pane can beused whenever catalogued stars are visible in the mainwindow. (Some stars do not have sufficient data to beplotted on the H-R diagram)

If a small telescope is available, it is strongly suggestedthat observations of some colorful stars like Albireo beattempted.

Students can be expected to complete this exercise in35 to 45 minutes.

Conclusion

Stars are not simple points of light. After completing these activities and exercises, students should know that stars have a range of properties. They should understand that thecolor, temperature and mass of a star are inter-related. Students should know that the mass ofa star governs everything about the star. Studentsshould know the apparent brightness of a starcannot be used to judge its distance.

Lesson Specific ResourcesSkyGuide

Guided Tours>Our Solar System, the Stars andGalaxies> The Stars

Guided Tours>Our Solar System, the Stars andGalaxies> Nebulae

Guided Tours>Our Solar System, the Stars andGalaxies> Novas and Supernovas

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Lesson Plan G2 The StarsStudent Worksheet: Hertzsprung-Russell Diagram

Table G2a Star Comparison Chart

Use the information in this table to help build your own H-R diagram.

Star Color Temperature in Mass in terms Power in Radius in terms Distance in degrees Celsius of solar mass Suns of Solar Radii Light Years

Sun Yellow 5,700 1 1 1 8 light min.Proxima Centauri Red 2,300 0.1 Unknown Unknown 4Barnard’s Star Red 3,000 0.1 0.01 0.2 6Epsilon Eridani Orange 4,600 0.1 0.4 0.8 11Alpha Centauri Yellow 6,000 1 2 1.4 4Altair White 8,000 3 12 2 17Vega White 9,900 3 61 3.3 25Sirius White 10,000 3 27 2 8.6Rigel White 10,000 3 52,000 92 777Regulus White 11,000 8 221 4.3 78Hadar Blue 25,500 20 79,000 24 526Alnilam Blue 27,000 20 112,000 44 1,360

Blue White Yellow Orange Red0

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Starry Night Computer Exercises Name:

Lesson G2: The Stars Class:

Instructions for the Student

Click on the SkyGuide pane, choose Student Exercises > G – Stars > G2: The Stars and follow the instructionsgiven. Record your answers to the questions in the spaces provided. Leave the last column blank for now.

Right click on each star and choose “Show Info” from the menu. Under the headings “Position inSpace” and “Other Data” you will find all the information you need to complete the chart.

Star Database

Star Color Distance Radius Apparent Temperature Luminosityfrom Sun in compared magnitude in Kelvinslight years to Sun

Sirius

Aldebaran

Pollux

Capella

Procyon

Orange

Return to SkyGuide to complete the rest of the exercise.

Question 1: Colorful stars

a) Do all stars have approximately the same temperature? Explain.

b) What seems to be the color of stars that have a temperature in the 3000’s degrees?

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Lesson G2: The Stars

c) Pick any other orange star in the main window and enter its name and temperature in the table.Was your prediction in b) correct?

d) Are all stars about the same size?

e) Do stars always appear brighter when they’re closer to us? Explain.

f) Do bigger stars always appear brighter to us? Explain.

Question 2: In the beginning

Why are stars born in a nebula?

Question 3: Going out gently

Why is the central star of the nebula difficult to see?

Question 4: Going out with a bang

The Crab Nebula requires a telescope to see. Telescopes were not invented until the 1600’s. Howcould the supernova have been seen in 1054?

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Lesson G2: The Stars

Question 5: The H-R Diagram

All the stars shown in the main window are plotted on the H-R diagram. Point to any star in themain window and a red dot will show its position on the H-R diagram. Go ahead, try it!

a) Now let’s fill in the last column on your Star Database. Record to what group each star in yourdatabase belongs. (i.e. red giant, main sequence etc)

b) To what group do you think the star Rigel belongs? (Hint: read the introduction carefully)

Return to SkyGuide to complete the Extra Credit for this exercise.

Extra Credit

a) What appear to be the colors of Albireo and its companion?

b) What do the colors of these two stars tell us about their surface temperatures?

c) How would you find Albireo in the summer sky?

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The Milky Way From: The University of Texas at Austin (McDonald Observatory)

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24 S TA R D AT E / U N I V E R S O T E A C H E R G U I D E

Stretching across the dark night sky, not easily visible when the Moonis in the sky, is a faint irregular glowing strip of light. For thousands ofyears peoples of various cultures tried to explain what they saw, some-times using stories. Here are some examples:

ChineseThe seventh Princess of Heaven fell in love with a poor herdsman andran away to marry him. When her mother sent soldiers to bring herhome, the herdsman chased them away. Seeing her daughter’s husbandrunning, the mother dropped a silver pin to make a silver stream to sepa-rate the lovers forever. Eventually, her father allowed her to have anannual reunionwith her husband— black birdsescorted heracross the stream.The Milky Way isthat silver stream.The young loversare the stars Vegaand Altair oneither side of it.

NavajoWhen the world was created, the people gathered around Black God toplace stars in the sky. Coyote was frustrated by how long it was taking.He threw the bag of stars over his head, forming the Milky Way.

EgyptianThe goddess Isis spread large quantities of wheat across the sky. We seethis bounty as the Milky Way.

African BushmenThe Milky Way is made of the ashes of campfires.

PolynesianThe Milky Way is a long, blue, cloud-eating shark.

GreekThe Milky Way is along the circular path where the Sun once movedacross the sky. It looks different than the rest of the sky because the Sunscorched it.

ACTIVITY 1Show students a picture of the Milky Way. Read several of the selectionsabove. Tell them to work in groups to make up a story and picture thatexplains how someone living thousands of years ago in their locationmight have explained it. When the pictures are done, have each grouppresent its report. For a link to Social Studies, have them choose a civi-lization to research to discover what important elements of their cultureare reflected in these stories.

The Milky WayAAGGEE OOFF TTHHEE MMIILLKKYY WWAAYYThe Milky Way arches high overhead

this evening.This subtle band oflight is the combined glow ofmillions of stars, which outline

the flat disk of our Milky Way Galaxy.Everything about the Milky Way is

gigantic. Its disk spans 100,000 light-years, and contains hundreds of bil-lions of stars. And according to a teamled by University of Texas astronomerChris Sneden, it’s about 14 billionyears old, give or take a few billion.

Astronomers arrived at this age bymeasuring the age of a single star.Thegalaxy can’t be any YOUNGER than itsoldest stars, so this technique yields aMINIMUM age for the Milky Way.

Astronomers determined the star’sage by measuring its chemistry. Theyfound that it contains only minutetraces of anything heavier than hydro-gen and helium, the two lightest ele-ments.That alone shows that the starmust have formed early in the historyof the Milky Way, since heavier ele-ments were forged inside stars, thenexpelled into space, where they couldbe incorporated into NEW stars.

One of the most important tracersof the star’s age is a radioactive ele-ment called thorium.The star containsonly about half as much thorium asexpected.Thorium has a half-life of 14billion years. In other words, in 14 bil-lion years, half the star’s thoriumshould have turned into other ele-ments. Since half of the thorium hasdisappeared, astronomers deduce thatthe star is about 14 billion years old —and so is the Milky Way.

Sun

Globular Clusters

100,000 light-years

27,000 light-years

Edge-on Milky Way

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S TA R D AT E / U N I V E R S O T E A C H E R G U I D E 25

BACKGROUNDGalileo, the first person to look at the sky with a telescope, discoveredthat the Milky Way is actually made up of countless faint stars. Otherastronomers discovered it also had many star clusters and nebulae(clouds of gas and dust). In the 20th century, astronomers put togetherclues from many types of observations to deduce that we live at the edgeof a spiral arm in the Milky Way galaxy. Because we are in the arm, welook at the rest of the galaxy edge-on and don’t easily see its structure. Ifwe could take a picture of the Milky Way from a vast distance, we wouldsee it as a majestic cosmic pinwheel. The Sun is just one of hundreds ofbillions of stars in the Milky Way galaxy. The stars in the arms areyoung, and many of them are hot and blue. The stars in the core andbetween the spiral arms are mostly older and redder.

ACTIVITY 2Examine color pictures of spiral galax-ies. Using them as examples, take yel-low and red fluorescent poster paint tomake a nucleus-shape in the center of apiece of black paper. Add blue spiralarms swirling out from the center.Within the arms, glue small pieces ofcotton balls to indicate the gaseous neb-ulae. Add a flag attached to a toothpicksaying “You are here” to indicate theSun’s position about two-thirds of theway from the center, on the edge of aspiral arm.

NATIONAL SCIENCE EDUCATION STANDARDS

• Content Standard in 9-12 Science asInquiry (Abilities necessary to do sci-entific inquiry)

• Content Standard in 9-12 Historyand Nature of Science (Science asa human endeavor, Historical per-spectives)

Seen from a distance, our Milky Way galaxy would look something like the twomajestic spirals at left. From our earthly vantage point, infrared telescopes canpeer through the intervening dust into the heart of the Milky Way (above, in red),27,000 light-years away.

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© April 2011 The University of Texas at Austin • McDonald Observatory

The Milky Way

Texas Essential Knowledge and Skills

Science, grade 8:

§112.20.(b)-8(A) describe components of the universe, including stars, nebulae, and galaxies, and use models such as the Herztsprung-Russell diagram for classification.

§112.20.(b)-8(B) recognize that the Sun is a medium-sized star near the edge of a disc-shaped galaxy of stars and that the Sun is many thousands of times closer to Earth than any other star.

Astronomy, grades 9-12:

§112.33.(c)-4(A) research and describe the use of astronomy in ancient civilizations such as the Egyptians, Mayans, Aztecs, Europeans, and the native Americans.

§112.33.(c)-4(B) research and describe the contributions of scientists to our changing understanding of astronomy, including Ptolemy, Copernicus, Tycho Brahe, Kepler, Galileo, Newton, Einstein, and Hubble, and the contribution of women astronomers, including Maria Mitchell and Henrietta Swan Leavitt.

§112.33.(c)-6(C) examine the scale, size, and distance of the stars, Milky Way, and other galaxies through the use of data and modeling.

§112.33.(c)-12(B) recognize the type, structure, and components of our Milky Way galaxy and location of our solar system within it.

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The Universe: Big Bang Balloon From: Discovery Channel School’s Curriculum Center

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hands-onactivities

The UniverseBig Bang Balloon

Background InformationIn the 1920s astronomer Edwin Hubble used the red shift of the spectra of stars todetermine that the universe was expanding. By carefully observing the light fromgalaxies at different distances from Earth, he determined that the farther somethingwas from Earth, the faster it seemed to be moving away. This relationship has becomeknown as Hubbleís Law, and itís just one piece of a bigger puzzle known as the BigBang theory.

Developed over many years and by many people, the theory states that about 15 billionyears ago the universe was compressed into an infinitely small space, known as theprimordial atom. It exploded in a sudden burst of energy and created a small, superdense,extremely hot universe that began to expand in all directions. Over time things cooled,and tiny bits of matter clumped together to form stars and galaxies. As a result of thisexplosion, all of these objects are still moving away from each other. In this experiment,you'll create a simple model to learn how the universe expands over time.

What You Needï 12-inch (30-cm) round latex balloonï a permanent felt-tip marking penï 24-inch (60-cm) piece of stringï metric ruler

What to Do1. Inflate your balloon until it is about 4 inches (10 cm) in diameter, but do not

tie the end.2. Using the felt-tip marker, make six dots on the balloon in widely scattered

locations. Label one dot "home" and the others A-E. The home dot representsthe Milky Way galaxy, and the others represent galaxies formed in the earlyuniverse.

3. Without letting air out of the balloon, use the string and ruler to measure thedistance from home to each dot. Record the distances in the worksheet tableunder the heading "Time 1."

4. Inflate the balloon so that its diameter is about 2 inches (5 cm) bigger. Againmeasure the distances to each of the dots, and record the distances under "Time2" on the worksheet.

5. Inflate the balloon in 2-inch (5-cm) increments three more times. After eachinflation, measure and record the distances on the worksheet.

6. Answer the follow-up questions on the worksheet.

http://www.discoveryschool.com/curriculumcenter/universe

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hands-onactivities

The Universe

http://www.discoveryschool.com/curriculumcenter/universe

Big Bang Balloon Worksheet

Name:

How did the distance from the home dot to each of the other galaxies change each time youinflated the balloon?

Did the galaxies near home or those farther away appear to move the greatest distance?

Record your measurements below.

How could you use this model to simulate the ìBig Crunch,î a time when all the galaxies mightcollapse in on themselves?

Distance Time 1 Time 2 Time 3 Time 4 Time 5from home

Dot A

Dot B

Dot C

Dot D

Dot E

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References for Activities

Starry Night Activity Pack

"Starry Night." Starry Night. Starry Night, n.d. Web. 14 July 2014.

The Milky Way

"Classroom Activities and Resources." McDonald Observatory. The University of Texas at

Austin, McDonald Observatory, Apr. 2011. Web. 14 July 2014.

<http://mcdonaldobservatory.org/teachers/classroom>.

The Universe: Big Bang Balloon

The Universe. Boston: Pearson Prentice Hall, 2006. Dsicovery Channel Schools. Discovery

Channel School's Curriculum Center. Web. 14 July 2014. <www.discoveryschool.com>.

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