July 21, 2004 Tea Break It took Voyager 20 years to get to Pluto. At the same speed, how long does it take to get to the nearest star? How long will it take to get to the center of the Galaxy?

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

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

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.

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

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.

July 21, 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)

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.

July 21, 2004 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

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

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

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.

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

July 21, ) 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/

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.

July 21, ) 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

July 21, 2004 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.

July 21, 2004 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.”

July 21, 2004 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?”

July 21, 2004 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…

July 21, 2004 Objects in the Universe An overview of what and where… Now that 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.

July 21, 2004 Now go back and check you images on the poster… Are they all in the correct spot? How do they need to be changed? Change them! Objects in the Universe An overview of what and where…

July 21, 2004 How old is the Universe? Insert Lindsay’s things here.

July 21, 2004 Reflection and Debrief

July 21, 2004 Reflection and Debrief (Evaluate) Now what do we know? What are the big ideas here? What do our students need to know? Is there anything else we need to know? Misconceptions (take notes)

July 21, 2004 Reflection and Debrief (Evaluate) What are some of the effective ways to teaching these topics? Standards??? (take notes)

July 21, 2004 Backup (CGRO)

July 21, 2004 CGRO ( )

July 21, 2004 BATSE

July 21, 2004 OSSE

July 21, 2004 COMPTEL

July 21, 2004 EGRET