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Passport Science Space Unit – Part 1 of 3 PowerPoints (Textbook reference Chapters 12, 13, 14, 15 and 16) 1 What is astronomy? •Stars •Nebula •Planets •The Sun •The Great Andromeda Galaxy by George Greaney •Star clusters •Galaxies •Galaxy clusters •Dark matter •Black holes What is astronomy? Astronomy is a science that attempts to understand the make-up and the M83 in Hydra history of the universe.Galaxy by George Greaney M33, The Pinwheel Galaxy in Triangulum by George Greaney What is astronomy? M33, The Pinwheel Galaxy in Triangulum by George Greaney Basically, if its off this planet its a study of some realm of astronomy. As one might imagine that covers an awful lot of subjects, even more than we know right now. •NGC 253, galaxy in Sculptor Key Ideas • Galaxies: clusters of stars; different shapes • Stars: Sun; differ in size, temperature and color; source for all bright objects • Gravity: planets, stars, solar system • Know the appearance, composition, position and size, and motion of objects in our solar system • Astronomical units for measuring 7 What is a Meteor? What is a Star? ? ? ? What is an Open Cluster? What is a Nebula? What is a Comet? ? ? ? What is a Quasar? What is a Black Hole? What is an astronomer ? Galileo Galilei (1564-1642) A night watchman with a college education? An astronomer is a scientist, skilled in mathematics, physics, and astronomy. Most professional astronomers work for universities or government agencies. Galileo Observatory in Italy Source: The Berkeley Cosmology Group Few astronomers spend much time looking through a telescope. Most operate telescopes from a control room or even from their computer at home via the Internet. Typical astronomers only spend one or two weeks each year observing, and the rest of their research time analyzing their data. Source: Applied Theoretical and Computational Physics Division Los Alamos National Laboratory Astronomer Serena Kim at work At Cerro Tololo in Chili What is an amateur astronomer? Amateurs and their tools What is an amateur astronomer? Although the term has different meanings for different people, a basic definition would include anyone who looks into the sky, and wants to see or learn more. What is space like? • No air • No gravity-when you’re not very close to a planet, sun, or moon • No wind • No friction • No real “up” or “down” • No pressure The Expanding Universe 15-5 • The Big Bang Theory 15 What is a “galaxy”? (Textbook reference 15-4) • A large group of stars outside of our own Milky Way • Made of billions to trillions of stars – Also may have gas and dust • Spiral, or elliptical, or irregular shaped – The Milky Way Galaxy is a spiral galaxy. Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2007/41/results/50/ Spiral galaxy--Andromeda NOAO/AURA/NSF Images at http://www.noao.edu/image_gallery/html/im0606.html and http://www.noao.edu/image_gallery/html/im0685.html Elliptical Galaxies Images at http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/2007/08/image/a/format/large_web/results/50/ and http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/1995/07/results/50/ Irregular Galaxies NASA and NOAO/AURA/NSF Images at http://hubblesite.org/newscenter/archive/releases/galaxy/irregular/2005/09/results/50/ , http://www.noao.edu/image_gallery/html/im0560.html , and http://www.noao.edu/image_gallery/html/im0993.html Our Galaxy: the Milky Way • has about 200 billion stars, and lots of gas and dust • is a barred-spiral (we think) • about 100,000 light-years wide (a measure of distance) • our Sun is halfway to the edge, revolving at half a million miles per hour around the center of the Galaxy • takes our Solar System about 200 million years to revolve once around our galaxy The Milky Way Image at http://news.nationalgeographic.com/news/bigphotos/1945371.html Mapping the Milky Way How do we know what our galaxy looks like? We can see – stars – star clusters – nebulae – galaxies Reviewing Galaxies • Groups of stars, planets, and space debris • Irregular, Elliptical, Spiral • Milky Way is our galaxy 23 What Is a Star? Image of the Sun from Goddard Space Flight Center What is a Star? Our Sun is the closest star. At the simplest, a star is just a ball of gas that has condensed out of interstellar material. The largest part of its lifetime is spent as a main sequence star during which hydrogen is being converted to helium balancing gravitational contraction so that the radius and energy output remain almost constant. Source: The British Astronomical Association Stars (Textbook reference 15-2 and 15-3) • Bodies of gases that give off tremendous amounts of radiant and heat energy • Constellations are patterns of stars used for navigation, storytelling, honoring heroes Life Cycle of a Star Video 26 Nearby Stars: Name Distance from Earth Sun 93 million miles (8 light minutes) Proxima Centauri 4.22 Light Years Alpha Centuri A,B 4.39 Light Years Barnards Star 5.94 Light Years Wolf 359 7.8 Light Years Lalande 21185 8.3 Light Years Sirius A,B 8.6 Light Years Image courtesy of Dave Dockery Astronomical Society of Las Cruces Source: The British Astronomical Association Evolution of Stars 28 How do Black Holes form? 29 Black Holes • Remains of a neutron star that has collapsed due to intense gravity 30 Hertzsprung-Russell Diagram Video on the Hertzsprung-Russell Diagram The Doppler Effect: Spectroscopy Video Red Shift – stars moving away from Earth Blue Shift – stars moving toward Earth 31 Hertzsprung-Russell Diagram The coolest stars are bluewhite in color. Images from http://www.nasa.gov/centers/goddard/news/topstory/2007/spectrum_plants.html and http://sunearthday.gsfc.nasa.gov/2009/TTT/65_surfacetemp.php Using a Star’s Spectrum • We can use a star’s spectrum to classify it. NOAO/AURA/NSF image at http://antwrp.gsfc.nasa.gov/apod/ap010530.html