CHAPTER 25: STARS AND GALAXIES

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CHAPTER 25STARS AND GALAXIES
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I. STARS
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A. ADVANCEMENTS IN ASTRONOMY

• NICHOLAS COPERNICUS
• TYCHO BRAYE
• JOHANNES KEPLER
• GALILEO
• NEWTON

see board
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B. THE SUN

• THE ONLY STAR IN OUR SOLAR SYSTEM
• MADE MOSTLY OF HYDROGEN AND HELIUM
• MAKES UP 99.86 OF THE MATTER IN THE SOLAR SYSTEM

see board for drawing
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C. STARS

1. BRIGHT, HOT SPHERES OF GAS
2. SOME STARS APPEAR BRIGHTER THAN OTHERS

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C. STARS(cont.)

• The color of a star indicates its
  temperature.
• Astronomers study the composition of stars by
  observing their spectra (its visible light color
  break down).

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1) MAIN SEQUENCE STARS

• BLUE 25,000-50,000
• BLUE-WHITE 11,000-75,000
• WHITE 6,000-7,500
• YELLOW 5,000-6,000
• ORANGE 3,500-5,000
• RED 3,000-3,500

All in degrees Celsius
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2) VARIABLE STARS

• STARS THAT EXPAND AND CONTRACT (CAUSING THEM TO
  GIVE OFF DIFF. AMTS. OF LIGHT)
• MULTIPLE STAR SYSTEM

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D. LIFE CYCLE OF A STAR

• NEBULA
• MAIN SEQUENCE
• GIANTS
• WHITE DWARF
• NOVA
• NEUTRON STAR
• BLACK HOLE

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see diagram on board
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II. GROUPINGS OF STARS
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• A. SOLAR SYSTEM
• B. CONSTELLATIONS
• C. GALAXIES
• (ELLIPTICAL, SPIRAL, IRREGULAR)
• D. CLUSTERS
• E. UNIVERSE

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F. THEORY OF RELATIVITY

• A THEORY OF THE NATURE OF SPACE, TIME, AND MATTER

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2Emc

• Eenergy
• mmass
• cspeed of light
• (299,792,458 ² km/sec)

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Einstein showed that mass is never lost, but
it may change to energy or a different form of
matter
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G. Big Bang Theory

• States that a fireball exploded 10-20 billion
  years ago and matter and energy spread apart in
  all directions.

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Big Bang Theory (cont.)

• Materials from the explosion formed clouds and
  from the clouds galaxies were formed during the
  next 1/2 billion years.

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• 1st generation stars the first stars to form in
  a galaxy
• 2nd generation stars form from the clouds of
  gas and dust from dying 1st generation stars

Ex. Our Sun
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H. SETI Search for Extraterrestrial Intelligence

• Uses radio telescopes.
• They constantly listen to radio signals in hopes
  of receiving signals from outer space.

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THE END