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8th Grade Chapter 2 Lesson 2
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8th Grade Chapter 2 Lesson 2

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8th Grade Chapter 2 Lesson 2 Presentation Transcript

  • 1. 8 th Grade: Chapter 2 Lesson 2 Pgs. 68-74 For Student Use Only
  • 2. Visible Light
    • Light:
      • Astronomers use the telescope to look at the world.
        • There are 2 types of visible light telescopes:
          • Refracting Telescope: Uses lenses to gather light and form an image
          • Reflecting Telescope: uses lenses and mirrors to produce an image
  • 3. Visible Light
    • Refracting Telescope:
      • It is made from a closed tube with an objective lens (large convex lens) at the top and an eyepiece (small convex lens) at the bottom.
        • Objective lens- collects light, bends (refracts) rays of light
        • Focal point- the point where light rays converge (meet)
        • Eyepiece: magnifies the image and enlarges the picture
  • 4. Visible Light
    • Reflecting Telescope:
      • Uses a large curved mirror in place of an objective lens
      • Lenses refract different colors of light at different angles and makes it hard to keep images sharp; BUT, mirrors reflect colors at the same angle and produce a sharper image
      • When parallel beam of light falls onto parabolic mirror, they reflect and are brought to focus at a point in front of the mirror.
  • 5. Visible Light
    • Reflection Telescopes:
      • Largest Reflecting Telescope:
        • 394 inch (10 meter) main mirror
        • Located in Hawaii
        • W. M. Keck Observatory
  • 6. Visible Light
    • Telescopes:
      • Astronomers use telescopes and cameras.
        • Use of camera help astronomers study the composition of stars.
        • Certain gases allow certain colored light to pass through due to the make up of gas.
          • Absorption Lines: dark lines that show which light has been absorbed.
  • 7. Visible Light
    • Light Spectrum:
      • Spectroscope: a device that splits light into a spectrum for analysis
      • Spectrograph: device used to study the spectra produced by the spectrascope
        • These devices help scientists know what elements are in each stars
  • 8. Visible Light
    • Radio Astronomy:
      • The weather often causes problems for optical telescopes.
        • Clouds, smog, and haze can hinder view of the stars.
        • Scientists use radio waves to also study stars. These can be studied rain or shine and can see things the eye cannot.
          • Radio Telescope- instrument that collects radio waves from space.
  • 9. Visible Light
    • Radio Astronomy:
      • The largest fully maneuverable radio telescope is in Germany
        • Effelsberg telescope is 328 foot long
      • Largest Stationary Radio Telescope:
        • Built in a natural depression in the mountains of Puerto Rico.
        • It is 1000 ft. across
  • 10. Visible Light
    • Singing Stars:
      • Radio Telescopes let astronomers listen to stars (and the radio waves that it produces)
        • Pulsars- are stars that produce rapid bursts of radio waves
      • Revelations:
        • Computer technology has helped astronomers study even more with Radio Astromomy.
  • 11. Visible Light
    • Radio Telescopes:
      • Scientists have used radio telescopes to take pictures of Venus
    • Radio telescopes have also helped to discover BLACK HOLES
      • Black Hole: an object that is so massive and dense that that not even light is fast enough to escape from its surface.
  • 12. Visible Light
    • Overcoming Obstacles:
      • Astronomers probing the heavens with visible light have always contended with several obstacles to their observations.
        • Extreme Faintness of the light
        • Earth’s atmosphere:
          • Air currents make the stars twinkle, but ruin pictures.
  • 13. Visible Light
    • Overcoming Obstacles:
      • NASA put a telescope above the thickest part of the atmosphere
        • This was to overcome the shimmering of the stars
      • Telescopes are put in space to help overcome obstacles.
        • Hubble Space Telescope helps astronomers see into space