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Cht . 4 Telescopes and Characteristics of Stars

Cht . 4 Telescopes and Characteristics of Stars. I. Telescopes – 1608 Galileo found moons! Light - (EM radiation) must be captured and enLARGED ! EM - radio, microwave, infrared, uv , x-rays, gamma. (Really, Mike, I see you except for games!)

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Cht . 4 Telescopes and Characteristics of Stars

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  1. Cht. 4 Telescopes and Characteristics of Stars • I. Telescopes – 1608 Galileo found moons! • Light - (EM radiation) must be captured and enLARGED! • EM - radio, microwave, infrared, uv, x-rays, gamma. • (Really, Mike, I see you except for games!) • Visible red lift . .violet right. Yellow middle..

  2. Now you must: • Make your own EM spectrum on paper (copy page 119) and come up with a short saying to remember the 7 different forms. Microwave is between radio and infrared.. • Make an HR Diagram – copy from 132 of book. Make supergiants, giants, main sequence, and white dwarfs – circle them as they do but name your own stars – put at least 3 in each group and summarize what these groups of stars represent as far as brightness and temperature.

  3. EM Spectrum – includes all the different types of EM waves!

  4. Light through a prism = spectrum

  5. Reflecting Telescope – largest today are this kind. Like a microscope - gathers and focuses light – but this uses a mirror!

  6. Refracting Telescope – uses convex lens to gather and focus light

  7. Telescopes of the Past

  8. Radio Telescopes - - focus radio waves on small antennas

  9. Observatories – building w/1 or more telescopes • Located on mountains or in space Light pollution is reason. Mauna Kea – 4200 m above sea level.

  10. Telescopes in Space • X rays, gamma rays, and most UV radiation is blocked by our atmosphere. Hubble telescope is in space – has 2.4 meter mirror – gives visible light, uv, and infrared radiation.

  11. Pictures taken by the Hubble • The Cat’s Eye Nebula

  12. The Sombrero Galaxy 28 million light years away

  13. The Trifid Nebula 9000 light years away!

  14. Constellations – groups of stars. This one is Cassiopeia • We use these to locate objects in night sky

  15. How do we classify stars? • Color – red is coolest, yellow middle, blue hot • Temperature – 3200 degrees C – red • 6000 is our sun • 20000 is blue

  16. Size as well as chemical composition • Our sun is medium, some are giant stars or supergiants. Some are smaller than sun. White dwarfs – Earth size • Neutron stars – 12 miles in diameter • Chem. Composition of most is 73% H, 25% He, and 2% other. • Spectrograph breaks light into colors and gives an image of spectrum. See page 128.

  17. Brightness of stars depends on size and temp. • Cool, large star (BG) can give off lots of light! • Small, hot star (Rigel) shines brightly! • How bright from Earth depends on its distance from us and how bright it TRULY is. • Apparent Brightness (brightness as seen from Earth). A close star may appear brighter . . • Absolute brightness – brightness it would have if it were at a standard distance from Earth. • Astronomers must find apparent brightness and its distance from Earth!

  18. Measuring distances to Stars – the light year. . .168,000 miles per second! • Parallax – the change in position of object when you look at it from different position.

  19. The Hertzsprung – Russell Diagram (HR diagram) – used to understand how stars change over time. Main sequence – diagonal area. More than 90% of stars are in Main sequence.

  20. Another example of HR Diagram

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