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Transcript
Astronomy: Telescopes and Studying the Stars 2012-2013 Astronomy: Telescopes and Studying the Stars I. Telescope Overview II. Read Chapter 1, Section 3 (pages 18-23) III. Directed Reading Worksheet (questions 1-20) IV. Making a Simple Lens V. Lenses and Mirrors VI. Reading Road Map for “Stars” (p. 98 – 104) VII. Is White White? VIII. Bill Nye Video and Worksheet IX. Astronomy Alphabet Soup 2 Telescope Overview Astronomy is the study of all physical objects beyond Earth. Before astronomy became a science, people in ancient cultures used the seasonal cycles of celestial objects to make calendars and organize their lives. Over time, some people began to observe the sky for less practical reasons – mainly to understand Earth’s place in the universe. Today, astronomers all over the world are using new technologies to better understand the universe. Galileo, in the year 1609, was one of the first people to use a telescope to make scientific observations of celestial bodies. Although his telescope was very simple and was equivalent to only that of most modern binoculars, some of Galileo’s discoveries led him to determine that the planets are not just dots of light in the night sky; instead, the planets are physical bodies like the Earth. This doesn’t seem like much to us during the 21st century but 400 years ago it was a major revelation! For professional astronomers and amateur stargazers, the telescope is the standard tool for observing the sky. A telescope is an instrument that collects electromagnetic radiation from the sky and focuses (or concentrates) it for better observation. There are different kinds of telescopes: optical telescopes and non-optical telescopes. The first telescopes were optical telescopes. This was what Galileo used. If your Uncle Vong owns a telescope or if your parents buy one at Gander Mountain, it’s going to be an optical telescope. An optical telescope is the kind you look through with the naked eye to see distant objects. In its most basic form, an optical telescope consists of two lenses and a tube in which the lenses fit. Non-optical telescopes are relatively new inventions of science. They include radio telescopes, ultraviolet telescopes, infrared telescopes, gamma-ray telescopes, and X-ray telescopes. These kinds of telescopes are used only by research scientists (although research scientists also use some optical telescopes). The “VLA,” a radio telescope located in New Mexico, consists of 27 separate “dishes” that can be moved around on tracks similar to railroad tracks. Each dish is 25 m in diameter. When spread out to their maximum distance, they work as a single telescope that would be 30 km (nearly 19 miles) across! Keep in mind, though, that you can’t “see” through a non-optical telescope like through an optical telescope. Non-optical telescopes don’t detect electromagnetic radiation in the visible spectrum. These kinds of telescopes need to be connected to special cameras and computers so that the incoming radiation can be processed and turned into a form that we can actually see. Optical telescopes come in two different styles – refracting telescopes and reflecting telescopes. Based on what you already know about refraction and reflection, can you figure out what each one is like or what each one consists of? Think about it for a minute and discuss it with a classmate. On the bottom of this page, sketch what you think each telescope might look like on the inside. (Remember the basic components of an optical telescope and be sure to label your diagrams!) Refracting telescope Reflecting telescope 3 Diagrams of refracting and reflecting telescopes are shown below. How do your sketches and ideas compare to the real thing? Were you on the right track? _________________________________________________ _________________________________________________ _________________________________________________ Refracting telescope: Reflecting telescope: Most professional astronomers and serious amateurs prefer reflecting telescopes. Based on the diagrams above and what you already know about glass, visible light waves, and refraction, can you come up with any reasons why a reflecting telescope might be better than a refracting telescope? ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ 4 Name: __________________________________ Per. _______ Questions: Answer the following after reading the “Telescope Overview.” 1. Without looking back at the reading, write your own definition of astronomy. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. How did ancient cultures first use the sky? ___________________________________________________________________________ ___________________________________________________________________________ 3. Why do scientists study the sky? ___________________________________________________________________________ ___________________________________________________________________________ 4. Who was one of the first people to put a telescope to scientific use? ____________________ 5. How many years ago did this person first begin using the telescope to make scientific observations of the sky? __________________ 6. Would you be more likely to use an optical or non-optical telescope? ___________________________________________________________________________ 7. Do you consider an optical or non-optical telescope to be more technologically advanced? __________________________________________________________________________ 8. What is the main difference between a refracting telescope and a reflecting telescope? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 5 Name: _________________ Directed Reading Worksheet Chapter 1, Section 3 (P.18-23) 1. What do telescopes do with electromagnetic radiation? _________________________________________________________ _________________________________________________________ _________________________________________________________ 2. The simplest telescope contains two lenses-an objective lens and a lens located in the ___________________ of the telescope. 3. As many as ___________________ stars are visible in the sky without a telescope. 4. Why do most professional astronomers use reflecting telescopes? _________________________________________________________ _________________________________________________________ _________________________________________________________ 5. Which of the following is NOT true of reflecting telescopes? a. They use curved mirrors to collect light. b. Flaws in the glass don’t affect the collected light. c. Different colors of light are focused in one place. d. Lenses gather and focus light. 6. Why is a mountaintop the best place on Earth to put a telescope? _________________________________________________________ _________________________________________________________ _________________________________________________________ 7. The clearest images of objects in deep space are produced by a telescope in space. True or False? 8. Our bodies sense infrared radiation as _____________________. 9. James Clerk Maxwell discovered that light is a form of ________________ radiation. 6 Each of the following wavelengths is either blocked or unblocked by the Earth’s atmosphere. In the space provided, write B if the wavelength is blocked and U if the wavelength is unblocked. 10. ______ infrared radiation 11. ______ radio waves 12. ______ gamma rays 13. ______ X rays 14. A different type of telescope or ___________________________ is needed for each type of electromagnetic radiation. 15. In figure 24, what is the cloudlike object that goes across each picture? _________________________________________________________ _________________________________________________________ Mark each of the following statements True or False. 16. ___________ Optical telescopes are much larger than radio telescopes. 17. ____________ Small quantities of radio radiation reach Earth from objects in space. 18. Why can chicken wire be used as the surface of a radio telescope? _________________________________________________________ _________________________________________________________ _________________________________________________________ 19. In the ___________________ __________________ __________________ many radio telescopes are linked to work as one giant telescope. 20. The Chandra telescope is the most powerful infrared telescope ever built. True or False? 7 Making a Simple Lens Have you ever wondered what it is about a magnifying lens that makes it magnify? In this activity you’ll make a simple magnifying lens with a single drop of water! Materials: Piece of newspaper Piece of overhead transparency Beaker of water Plastic pipette Paper toweling Procedure: 1. Spread the piece of paper toweling on your table. 2. Lay the cut out piece of newspaper on the paper toweling. 3. Place the piece of overhead transparency on top of the newsprint. 4. Using the plastic pipette, carefully place a drop of water on top of the transparency. Don’t let the tip of the pipette touch the transparency or the water on the transparency! 5. You should look at the newsprint to see if its appearance has changed. 6. Look at the water drop from its side. Notice what shape it has. 7. Repeat steps 5, 6, 7, and 8 over adding one drop of water at a time. 8. Keep doing this as long as you can make the newsprint’s appearance change. Challenges: 1. Place a drop of water on the transparency and then pick up the transparency and move it away from the newspaper. What happened? 2. Attempt to place an air bubble inside of a water droplet. What happened? 8 Name: _________________________ Questions: 9. Sketch the shape of the water drop while it was on the transparency. In other words, sketch the water drop as it appeared while looking at it from its side, not while looking down on it. 10.What did the water drops do to the newsprint’s appearance? ________________________________________________________________ ________________________________________________________________ 11.Why do you think the water drops made the newsprint appear larger? ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ 12. Imagine that you are the first person in the world to have ever discovered this interesting characteristic of water. What could you have done with your knowledge? What “tools” could you have invented? ________________________________________________________________ ________________________________________________________________ _______________________________________________________________ 13.Water isn’t always very easy to work with, especially in this way. What do you think you could possibly use instead of water to achieve similar results? ________________________________________________________________ 9 Lenses & Mirrors Have you ever gone through a fun house and noticed how your appearance changes when you look at yourself with different shaped mirrors? Have you ever looked through a telescope or binoculars? These devices are made possible through the use of lenses and mirrors. Lenses and mirrors cause electromagnetic waves to be either refracted (bent) or reflected (bounced off) and this can cause images to appear larger, smaller, or even distorted. Materials: convex lens concave lens plane mirror concave mirror convex mirror metric ruler Concave Lens Concave Mirror Plane Mirror Convex Mirror Convex Lens Procedure: After you have the different lenses and mirrors at your desk, identify them with the diagrams in figure 1. If you are unable to identify them ask your teacher for help. Questions: 1. Which two of the above can make objects appear larger? ___________________________________ __________________________________ 2. List two of the above that can make objects appear smaller. ___________________________________ 10 __________________________________ 3. After experimenting with the various lenses and mirrors, complete the table below: Hold Lens or Mirror a distance of 10 –15 cm from an object with writing Type of Lens or Mirror Size of Image (Larger, Smaller, Same) Image Appearance (Right-side up, Upside down, Backwards) Hold Lens or Mirror at arms length and look at a distant object with writing Image Appearance Size of Image (Right-side up, (Larger, Smaller, Upside down, Same) Backwards) Concave Mirror Concave Lens Convex Mirror Convex Lens Plane Mirror 4. What type of lens would be used to make a magnifying glass? ________________________________________________________________________ 5. What type of mirrors do stores use to help prevent shoplifting? ________________________________________________________________________ 6. What is meant by the statement, “Mirrors cause images to be reversed”? ________________________________________________________________________ ________________________________________________________________________ 11 Name: _____________________________ Per.: _______ Reading Road Map for “Stars” p. 98-104 Use this Reading Road Map to guide you through the “Stars” section in your Astronomy textbook. The “Location” category tells you what to read; the “Speed” category tells you how carefully to read it; the “Mission” category tells you what you have to answer in the provided space. Have a great trip!! Location Speed Mission 1. What are stars? Top of p. 98 2. How do astronomers study stars? 3. Is Betelgeuse hotter or cooler than Rigel? “Color of Stars” (p. 98) 4. How can you tell? “Composition of Stars” (p. 98) 5. In what way is a spectrograph similar to a prism? 6. A star, therefore, produces a __________________ with various lines in it. “Hot, Dense Gas” (p. 99) 7. Emission lines are …. “Making an ID” (p. 99) 8. If you’re a scientist looking at a gas through a spectroscope and you see 2 green stripes and no red or orange stripes, what gas(es) would you probably not be looking at? Figure 2 (p. 99) 9. T or F A star’s atmosphere is cooler than the star itself. “Trapping the Light” (p. 99) “Cosmic Detective Work” (Figure 3 p. 100) 12 MINIMUM SPEED 80 10. An absorption spectrum is produced when ________________ passes through a ________________ gas. 11. Identify the element in the gas by comparing the position of the dark lines in its spectrum with the bright lines in Figure 2. Figure 3 (p. 100) 12. Stars were originally classified by (choose the best!) a. How big they were b. What gases they contained c. Where they were located 13. Stars are now classified by… “Classifying Stars” (p. 100) “Differences in Temperature” (p. 100-101) 14. The hottest stars are what color? “Differences in Brightness” (p. 101) 16. The magnitude of a star refers to how _____________ the star is. “How Bright Is That Star?” (p. 102) 17. Do you think all the street lights in the picture are all of the same actual brightness? In other words, do you think they all have the same kind of light bulb in them? 15. The hottest stars contain what element? “Apparent Magnitude” (p. 102) 18. Does the closer light in Figure 5 have an apparent magnitude greater or lesser than the light farthest away in the picture? “Absolute Magnitude” (p. 102) 19. Do you think the lights in Figure 5 have absolute magnitudes that are fairly equal? 20. What is a light year? “Distance to the Stars” (p. 103) “Motions of Stars” (p. 103) “Apparent Motion” (p. 104) “Actual Motion” (p. 104) 21. Why do astronomers use light years as a unit? MINIMUM SPEED 80 22. Why do we see different stars at different times of the year? (Looking at the bottom of Figure 6 might help you understand this.) 23. The sun and stars appear to move across Earth’s horizon because Earth is _________________. 24. The actual movement of stars is hard for us to observe because they are soooooo _____________ away. 13 Is White White? White light is made up of many different colors and these colors depend on the wavelength of the light. Light, however, that appears white might not be made up of exactly the same wavelengths as other light that appears to be white. Scientists have also learned that different chemical elements and combinations of chemical elements produce light made of different wavelengths of visible light. Instead of using a prism to separate out the different colors (wavelengths) that make up the light, scientists use a spectroscope. How does a spectroscope cause light to separate out into its various colors (wavelengths)? It uses diffraction. Diffraction is simply the bending (and separation) of light as it travels through a very narrow slit. Different wavelengths bend different amounts as they travel into a different medium? Different wavelengths do the same thing when they travel through a tiny slit. Your spectroscope has thousands of tiny slits in it!!!! This makes the light separate a lot so that it’s easy to see the different colors. How do you think astronomers can tell what chemical elements stars are made up of when they can’t get anywhere near the stars? They use spectroscopes! It isn’t always easy, though, because stars are made up of combinations of elements so it actually turns out to be a puzzle to figure it all out. Materials: Spectroscope Various Light Sources Colored Pencils (ROYGBIV) Procedure: 1. Look at the light source through the spectroscope. Follow your teacher’s instructions on how to properly use the spectroscope. 2. Color in the box to match what you see through the spectroscope. If the colors blend into one another, make sure you show that. If the colors are separate lines, make sure you show that, too. If some colors are stronger or weaker, show that, also. In other words, try to copy exactly what you see through the spectroscope! 1. Sunlight or Incandescent Light Bulb R O Y G B I V I V 2. Fluorescent Light (Ceiling Lights) R 14 O Y G B 3. Yellow Bug Light R O Y G B I V O Y G B I V Y G B I V Y G B I V Y G B I V I V I V 4. Ne (neon) R 5. N (nitrogen) R O 6. H (hydrogen) R O 7. He (helium) R O 8. ____________________________ R O Y G B 9. ____________________________ R O Y G B 10. Did you notice the numbers in your spectroscope? What do you think they are for? Discuss this with a classmate and write your answer below. ______________________________________________________________________________ ______________________________________________________________________________ 15 Name: _____________________ “Outer Space” (Bill Nye video) 1. Most of what we’ve learned about outer space we’ve learned the same way that people have learned about it for centuries – by _____________________________________________________________. 2. By looking at the stars, we’ve learned about ___________ ___________. 3. Everything “out there” is made of the _____________ _______________ as we are. 4. Some groups of billions of stars look to us like single stars because they’re so _______________ _______________ . 5. Light travels _______________ kilometers every second. This is about three-fourths of the distance to the moon in one second! 6. Things in the universe are so far apart that it can take light _______________ and _______________ of years to get from one place to another. 7. A light year is the _______________ that _______________ travels in one year. 8. Light travels about _______________ kilometers in one year. 9. Some of the stars we can see right now might not even _______ ________. 10.A constellation is a _____________________________________________ that we’ve given a name to help us find certain stars or to recognize them. 11.One of the easiest stars to find in the northern hemisphere is the _______________ _______________ , sometimes called ____________ . 12.Eventually, in about _______________ years, Earth’s northern axis will be pointing to the star Vega instead of _______________ . 16 13.Each star is like a _______________ . 14.Astronomers use astrolabes to find out about the _______________ of stars and to find _______________ . 15.The goal of scientists in general, and astronomers in particular, is to ___________________________________________________________ . 16.About _______________ years ago, a man named Eratosthenes figured out that Earth is _______________ and he was able to calculate the _______________ of Earth. 17.The ingredients to make virtually anything in the universe are __________. 18.Atoms come from _______________ . 19.Water is _______________ - which is _______________ parts H (hydrogen) and _______________ part O (oxygen). 20.To make all the different kinds of atoms, you need the force of _______________ stars and _______________ of years. 21.We are made of the same “stuff” as _______________ . 22.We have to study stars to understand what __________________________. 23.Since this video started, the light coming out of the television has traveled about ______________________________ kilometers. 17 Name:_______________ Astronomy Alphabet Soup Materials: Paper & Pencil Procedure: 1. Here are 64 letters: M, A, N, N, T, S, Y, O, O, L, M, E, A, D, L, G, Y, T, S, U, P, L, R, A, N, R, T, S, M, A, N, M, E, O, R, O, O, E, X, A, A, C, O, N, E, T, N, O, O, C, S, T, L, A, T, E, R, T, I, O, I, S, E, T. 2. The goal is to unscramble the letters to make ten astronomy-related words (Hint: the first word is in these instructions). You can unscramble the letters using a single sheet of paper and a pencil, but it may be easier if you write each of the letters on a separate slip of paper and then arrange the slips of paper. 3. Some of the words are easy; others are a little harder. Aside from the first word, all the words are natural objects in space (heavenly bodies). You must use up all the letters. Answers: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 18 M A N N T S Y O O L M E A D L G Y T S U P L R A N R T S M A N M E O R O O E X A A C O N E T N O O C S T L A T E R T I O I S E T 19 20