2. July 21, 2004

3. Topics of the Day The Electromagnetic Spectrum (1 hour) –Everyday detectors and Shields Powers of Ten Size and Scale of the Universe (.5 hour) Objects in the Universe (.5 hour) Scaling the Universe Now what do we know and what else should we know?

4. July 21, 2004 GEMS Activity 2 - Sources Question: Name some visible sources of light in the room Question: Is the screen at the front of the room a light source? Definition: Sources of light are objects that emit light energy Flashlight Projector Laptop Monitor But it seems to be emitting light? Oh, I see the screen is reflecting the light, not emitting it.

5. July 21, 2004 Question: Can you tell me where there are light detectors in this room? GEMS Activity 2 - Detectors Question: Are there any other light detectors that you know of? Those two openings on either side of our noses! Solar Calculators Motion Sensitive Light Switches Cameras

6. July 21, 2004 GEMS Activity 2 – Transmitters and Shields Question: What are some things that don’t allow light through? Is it safe to say these things “Shield the Light”? Question: What are some materials we know of that do allow light to either completely or partially pass through it? –Is it safe to say these things “Transmit the Light”?

7. July 21, 2004 GEMS Activity 2 – Invisible Sources In addition to visible sources of light in the room there are many invisible sources of light too. Question: Can anyone name any invisible sources of light in the room? Infrared Heat Lamps UV Black Light Infrared Remote Yes! Us.

8. July 21, 2004 GEMS Activity 2 – Invisible Sources of Light There are 6 different stations throughout the room, each with three setups. They are equipped with a source of invisible light and a detector for detecting that light. In a moment we will break up into groups. Each station will have a set of materials. These materials are potential shields.

9. July 21, 2004 GEMS Activity 2 - Procedure Each group will go from station to station. You have about 5 minutes per station. As scientists we are obligated to make a prediction about how we think each material will behave. DO THIS FIRST! Then test each material at each station to see if it is a Transmitter (T) or a Shield (S) for that particular type of light. Try to determine the common properties of the materials that block the different types of light

10. July 21, 2004 Stations: AM Radio Infrared lamp Flashlight FM Radio Remote control “Black” light Let’s Get Busy!

11. July 21, 2004 GEMS Activity 2 – What did we learn? Question: What property of the materials we tested caused radio waves to be blocked? Question: Are all the plastics we tested translucent/transparent to infrared light? Question: If someone had no sunscreen while at the beach what could they cover their face with to keep from getting sun burned by UV light?

12. July 21, 2004 GEMS Activity 2 – Reflection Each group should pick a station. Try to figure out which of your materials can reflect the invisible light of that station. Try and use what you have learned in the previous section to test your ideas in this section. Question: What did you find out?

13. July 21, 2004

14. Seeing the Light VLA MAP SIRTF EUVE Chandra GLAST HST/Keck

15. July 21, 2004 Looking back through space and time Constellation-X JWST, FIRST WMAP, Planck LISA, GLAST Big Bang inflation first stars, galaxies, and black holes clusters and groups of galaxies microwave background matter/radiation decoupling Early Universe Gap First Stars Gap

16. July 21, 2004 Powers of Ten Earth diameter ~1.3 x 10 4 km

17. July 21, 2004 Powers of Ten Solar System diameter ~5.9 x 10 9 km

18. July 21, 2004 Size and Scale of the Universe Image courtesy of The Cosmic Perspective by Bennett, Donahue, Schneider, & Voit; Addison Wesley, 2002

19. July 21, 2004 Earth Planet where we all live Comprised primarily of rock Spherical in shape 12,700 km in diameter It would take 17 days to circumnavigate the globe driving a car at 100 km/hr At the speed of light, it would take 0.13 seconds to go all the way around Earth.

20. July 21, 2004 Sun Star that Earth orbits Composed primarily of hydrogen and helium gas Uses nuclear fusion in its core to generate heat and light to allow itself to resist the crushing weight of its own mass Spherical in shape 1.39 Million km in diameter

21. July 21, 2004 Earth & Sun The Sun’s diameter is 109 times greater than that of Earth Over 1 million Earths would fit inside the Sun’s volume Earth orbits the Sun at an average distance of 150 million kilometers. This distance is called an Astronomical Unit (AU) It would take 11,780 Earths lined up side to side to bridge the 1 AU between Earth and Sun.

22. July 21, 2004 8.5 planets, thousands and thousands of planetoids and asteroids, billions of comets and meteoroids Mostly distributed in a disk about the Sun Sun blows a constant wind of charged gas into interplanetary space, called the Solar Wind The Solar System Boundary between Solar Wind and interstellar space at 100 AU from the Sun (200 AU diameter)

23. July 21, 2004 The Solar Neighborhood The region of the Galaxy within about 32.6 light- years of the Sun (65 light- years diameter) is considered its neighborhood. Here stars move generally with the Sun in its orbit around the center of the Galaxy This region is inside a large bubble of hot interstellar gas called the Local Bubble. Here the gas temperature is about 1 million degrees Kelvin and the density is 1000 times less than average interstellar space. Direction of Galactic Rotation To Center of Galaxy The image is 390 light-years across.

24. You Are Here The Milky Way Galaxy is a giant disk of stars 160,000 light-years across and 1,000 light-years thick. There are over 100 Billion stars in the Milky Way The Spiral arms are only 5% more dense than average, and are the locations of new star formation The Sun is located at the edge of a spiral arm, 30,000 light-years from the center It takes 250 Million years for the Sun to complete one orbit The Milky Way Galaxy

25. July 21, 2004 The Local Group Contains 3 large spiral galaxies--Milky Way, Andromeda (M31), and Triangulum (M33)—plus a few dozen dwarf galaxies with elliptical or irregular shapes. Gravitationally bound together—orbiting about a common center of mass Ellipsoidal in shape About 6.5 million light-years in diameter

26. July 21, 2004 The Local Supercluster A cluster of many groups and clusters of galaxies Largest cluster is the Virgo cluster containing over a thousand galaxies. Clusters and groups of galaxies are gravitationally bound together, however the clusters and groups spread away from each other as the Universe expands. The Local Supercluster gets bigger with time It has a flattened shape The Local Group is on the edge of the majority of galaxies The Local Supercluster is about 130 Million light-years across

27. July 21, 2004 The Universe 1.3 Billion light-years Surveys of galaxies reveal a web- like or honeycomb structure to the Universe Great walls and filaments of matter surrounding voids containing no galaxies Probably 100 Billion galaxies in the Universe The plane of the Milky Way Galaxy obscures our view of what lies beyond. This creates the wedge-shaped gaps in all-sky galaxy surveys such as those shown here.

28. July 21, 2004 The Universe Computer Simulation The observable Universe is 27 Billion light-years in diameter.

29. July 21, 2004 1) The Standard Ruler Use knowledge of physical and/or geometric properties of an object to relate an angular size with a physical size to determine distance. Ex: Parallax, Moving Clusters, Time Delays, Water MASERs Considered to be a direct or absolute measurement. There are two basic methods for measuring astronomical distances R d  d = R/Tan()  R/

30. July 21, 2004 Trigonometric Parallax Requires very precise measurements of stellar positions, and long baselines Need telescopes with high resolution, and must observe over several years. Hipparchos satellite measured distances to tens of thousands of stars within 1,500 light-years of the Sun.

31. July 21, 2004 2) The Standard Candle Use knowledge of physical and/or empirical properties of an object to determine its Luminosity, which yields distance via the Inverse Square Law of Light. Ex: Cepheid Variables, Supernovae, TRGB, Tully-Fisher Considered to be relative until tied to an absolute calibration. b = L/4d 2

32. Cepheid Variable Stars There is a kind of giant star whose surface pulsates in and out with a regular period. That period of pulsation is related to the Luminosity of the star. LMC contains hundreds of known Cepheids all at the same distance. Which allows for robust determination of the Period Luminosity Relationship.

33. To measure cosmological distances a ladder of methods is used to reach further out into the Universe. Each “rung” in the ladder of distance measuring methods depends on the calibration of the methods “below.”

34. Objects in the Universe An overview of what and where… Science Concepts: The scale and structure of the Universe is vast and complex. Objects in space are viewed across the whole electromagnetic spectrum. The Earth is one of many planets, in one of many solar systems, in one of many galaxies in our Universe. Goals: To give students a better grasp of where objects viewed by scientists in our Universe are located relative to Earth. To give the students a better understanding of how and why scientists view objects. To give students a better understanding of the structure and evolution of our universe and the objects it contains. Guiding Question: “What’s in the Universe?”

35. Where does everything go What do they know about these objects? Size, Distance, Age, and where are they relative to us. Are they inside our Solar System (near by), outside our Solar System but inside the Milky Way (Far), or outside the Milky Way (really far)? Now you try it! In groups take the little images of the objects and place them on the poster where you think they should be located in our Universe. Note these objects are images in various wavelengths. Objects in the Universe An overview of what and where… After you have placed your images on the poster… In your groups discuss the image cards together. With the information given on the cards fill out the worksheet so you have a better understanding of where those objects should be in our Universe. Now go back and check you images on the poster… Are they all in the correct spot? How do they need to be changed?

36. At the Inquiry Station: 2 Activities What do we know about what is out there The next phase of this inquiry station takes the students through a brief tour of the invisible universe. This is an activity from the GEMS Invisible Universe book produced by the Swift mission. Each object placed on the poster has a card associated with it. The students are asked to read these cards aloud in small groups. The cards contain a wealth of information for each object including its size of the object, the wavelength, the distance, and well known facts about similar objects. Once they review all of the cards the students then revise how they placed the objects on the poster.