Science- Unit 1 Space Chapter 9

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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 huge collection of stars, planets, gas, and dust that is held together by gravity
  3. Star cluster
    a collection of stars held together by gravity
  4. Open cluster
    a collection of 50 to 1000 stars; open clusters appear along the main band of the Milky way
  5. Globular cluster
    a collection of 100 000 to a million stars, arranged in a distinctive spheical shape; globular clusters appear around the centre of the milky way
  6. Local group
    the small group of galaxies that includes the Milky Way
  7. supercluster
    a gigantic cluster of 4 to 25 clusters of galaxies, which is hundreds of millions of light-years in size
  8. Shapes of galaxies
    Come in different shapes or sizes, they can either be classified as a spiral or elliptical galaxy, if they do not fit either of these catagories they are called irregular galaxies
  9. Spiral galaxy
    looks like a pinwheel when viewed from above, from the side a plate with a bulge in the centre
  10. Elliptical galaxy
    range from a perfect circle to a streched out ellipse, tend to contain the oldest stars in the universe, are the biggest
  11. Irregualr galaxy
    galaxies that do not have a regular shape, such as spiral arms or a central bulge
  12. Cosmology
    the study of the universe
  13. Doppler 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
  14. Redshift
    the effect in which objects moving away from an observer have thier wavelengths lengthened, toward the red end of the visible spectrum
  15. Blueshift
    the effect in thich objects moving toward an observver have thier wavelengths shortened, toward the blue end of the visible spectrum
  16. Big bang
    the event that may have triggered the expansion of the universe 14 billion years ago
  17. Cosmic microwave background (CMB) radiation
    the radiation left over from the big bang which fills the universe
  18. Dark matter
    the most abundant form of matter in the universe, invisible to telescopes
  19. Dark energy
    a form of energy that makes up nearly three quarters of the universe; has the effect of increasing the expansion of the universe
Card Set
Science- Unit 1 Space Chapter 9
Grade 9 science unit 1 space
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