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Pg. 46. Draw a rough sketch of the Milky Way galaxy and include the following (you may look up a picture of the galaxy on your phone or computer): the spiral arms Put a circle where the halo would be. Draw stars to represent the globular clusters
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Pg. 46 • Draw a rough sketch of the Milky Way galaxy and include the following (you may look up a picture of the galaxy on your phone or computer): • the spiral arms • Put a circle where the halo would be. • Draw stars to represent the globular clusters • Put a filled in circle where the nucleus and the nuclear bulge would be. • Where would the younger stars be located? • Where would the Population II stars be?
Other Galaxies and Cosmology Pg. 47
Classification of galaxies • Disk-like galaxies • Normal spirals- denoted by the letter S; normal nucleus • Barred spirals-denoted by SB; elongated central region from which the arms extend • Further broken down into a, b, and c categories that describe the arms and brightness • Elliptical galaxies • Not flattened into disks • No spiral arms • Classified from E0 (very round) to E7 (very elliptical)
Groups and Clusters of Galaxies • Milky Way belongs to a small groups called the Local Group • 35 known members (mostly dwarfs) • Most in inner region are elliptical, mix in the outer region • Clusters are organized into even larger groups called superclusters
The expanding universe • Edwin Hubble studied galaxies and their movements • Saw all were red-shifted • Farther from Earth the galaxies were, the faster they were moving away
Hubble’s Law • Made a graph of the speed at which the galaxy is moving away vs. the distance • v=Hd • v=speed (km/s) • d=distance to the galaxy (Mpc) • H=Hubble constant (slope of the line) • Once H is known, it can be used to measure far away galaxies
Quasars • In 1960, a new object was discovered • Emitted a lot of radio waves • Called quasars • Very bright and associated with galaxies • Very far away • When we observe it, we are really looking at it as it was years and years ago
Hubble’s Lawpg. 48 • Use the information on page 843 in the text book to determine Hubble’s constant. • Do numbers 1-4 on the Problem Solving Lab
Cosmology Pg. 49
Cosmology • The study of the universe and its origins and evolution
Models of the Universe • Big Bang: universe began as a point and has been expanding ever since • Steady-state theory: universe looks the same as it always has; doesn’t change with time
Support for the Big Bang theory • Scientists were picking up back ground noise in the form of radiation • Called cosmic background radiation • Interpreted to be radiation from the beginning of the Big Bang
The Inflationary Universe Model • Predicts that the universe is flat • Began as a fluctuation in a vacuum and expanded very quickly
Pg. 50 • Create a flow chart that describes the order of the following starting with the biggest to the smallest: • Planets • Universe • Galaxies • Solar systems • Galaxy groups • superclusters