Chapter 9 glossary terms

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Chapter 9 glossary terms
2013-01-16 20:18:50

Chapter 9 glossary terms for Mrs.Day
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  1. Milky way
    The galaxy that includes the solar system; appears as a hazy white band in the night sky
  2. Galaxy
     A collection of stars, dust, gas and planets all held together by gravity
  3. Star cluster
    A collection of stars held together by gravity
  4. Open clusters
    A collection of 50 to 1000 stars; open clusters appear along the main band on the Milky Way
  5. Globular clusters
    A collection of 100,000 to 1,000,000 stars that is arranged in a spherical shape and are found in the centre of the Milky Way
  6. Local group
    A small group of Galaxies (40) that include the Milky way
  7. Supercluster
    A gigantic cluster of 4 to 25 cluster galaxies that is hundreds of millions of light-years away
  8. Shapes of galaxies
    Spiral- A galaxy that looks like a spiral with extended arms comming out of it; we are locates in a spiral galaxy

    Oliptical- A galaxy that looks circular or ellipse that contains some of the oldest stars in the galaxy

    Irregular- A galaxy that dose not have a distictive shape but contains new and old stars
  9. Cosmology
    The study of the universe
  10. Doopler effect
    The change in frequency of a light source due to its motion relative to an observer; also, the change in pitch of a sound due to the motion of the source relative to an observer
  11. Redshift
    The effect in which objects moving away from an observer have their wavelenghts lenghthened
  12. Blueshift
    The effect in which objects moving toward the observer have their wavelenghts shortened
  13. Big bang
    The event that may have triggered the expansion of the universe 14 billion years ago
  14. Cosmic microwave radiation
    The radiation left over from the Big bang whcih fills the universe
  15. Dark matter
    The most abundant form of matter in the universe; inviasble to telescopes
  16. Dark energy
    A form of energy that makes up nearly 3 quarters of the universe; has the effect of increasing the expansion of the universe