Preface

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Preface

• This presentation compliments the 2 reading
  assignments that go with ch. 22.
• The slides identified with a Q are associated
  with the Reading Assignment on the Sun.
• The slides identified with a q are associated
  with the Reading Assignment on Intro. to
  Astronomy.
• In both of the above cases the number refers to
  the question from the reading guide.

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THE SUN

• Chapter 22

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Q1. Galileo Galilei

• Galileo made a good discovery great. Galileo
  discovered that our Moon had craters, that
  Jupiter had its own moons, that the Sun has
  spots, and that Venus has phases like our Moon.

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Q2. McMath Solar Telescope
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2a. Solar Telescope
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2b.
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2d.
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Q2e.
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2c.
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Q4. Suns Diameter
One Earth
The Sun is 110 times the diameter of the Earth
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Q5.
MOON
SUN
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Q9-12. Three Regions of Suns Atmosphere
corona
chromosphere
photosphere
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Q12 The Corona
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Q13. Three Regions of Suns Atmosphere
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Q8. Three Regions of Suns Atmosphere
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Q14 Sun Spots
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Q14 Sun Spots
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• Sunspot cycle

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• Sunspot cycle

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Q18. Solar Wind
A Stream of electrically charged particles
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Q19. What are Solar Flares?

• Source of solar winds.
• "A sudden, rapid, and intense variation in
  brightness.
• Outbursts of light that rise up suddenly in areas
  of sunspot activity.

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Q19a. When does a Solar Flare occur?

• A solar flare occurs when the magnetic energy
  built up in the solar atmosphere is released
  suddenly.
• Radiation from across the electromagnetic
  spectrum is released (radio waves to x-rays and
  gamma rays).
• The amount of energy involved in this release is
  the equivalent of millions of hundred megaton
  hydrogen bombs.

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Q20. Auroras Northern Lights
Finland
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• Southern Lights from Kangaroo Island, South
  Australia

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Q20. Auroras
Luceville, QuebecCanada
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Q20. Auroras
Cleary Summit, Alaska, USA
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• Aurora in west Texas skies.

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• Auroras can happen on other planets. A NASA
  satellite, the Hubble Space Telescope, took this
  image of an Aurora on Saturn's north and south
  poles

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Q21. Magnetic Storms
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Q21. Magnetic Storms
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Q22 What happens when hydrogen atoms fuse
together to form helium in the sun?

• The left over mass is converted to energy
• E mC2

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Q24 When will the Sun die?

• 5 billion years
• 5,000,000,000 years
• 5 x 109 years

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Q25 Ulysses spacecraft
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PART II Reading Assignment on Intro. to Astronomy
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q1. Geocentric solar system
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q2. Ptolemy
Geocentric solar system
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q3. Heliocentric solar system
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q3. Heliocentric solar system
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q3b. Copernicus
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q5. Tycho Brahe
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q5. Tycho Brahe Observatory
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q6. Johannes Kepler
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q7. First Law of Planetary Motion

• 1. Planets move around the Sun in ellipses, with
  the Sun at one focus.

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q8. Aphelion vs. Perihelion

• Study this picture.
• What is the aphelion (a feel yon) of an
  elliptical orbit? The Perihelion (pir y heel yon)?

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q9. Second Law of Planetary Motion

• 2. The equal area law Each planet moves
  around the sun in such a way that an imaginary
  line joining the planet to the sun will sweep
  over equal areas of space in equal periods of
  time.

x1
y2
30 days
30 days
A
B
y1
x2
Area of A Area of B
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q10. Third Law of Planetary Motion

• 3. The Harmonic Law
• The period of a planet squared is equal to the
  cube of its distance to the sun.

P2 D3
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q10. Keplers Third Law
Period (of a planet)
the time it takes for the planet to travel once
around the sun
What is the period of Earth?
365 days
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q10. Keplers Third Law
Astronomical Unit (AU)
The distance between the Earth and Sun
1 AU
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q10. Keplers Third Law
The farther the planet is from the Sun
the longer is its period of revolution
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q11. Galileo
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q11. Galileos observations

• Millions of stars where only thousands could be
  seen before

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q11. Galileos observations

• Craters mountains on moon

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q11. Galileos observations

• Observed Venus and discovered it went through
  phases like our moon.

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q11. Galileos observations

• Discovered 4 moons orbit around Jupiter

• What was significant about this?

• It supported the theory of a heliocentric system

• Why

• It showed not everything orbits the Earth as in a
  geocentric system.

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Galileos Observations
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q13. Issac Newton
Universal Law of Gravitation
The gravitational force between two objects is
directly related to the masses of the two objects
but
Huh? Can you explain that to me?
inversely related to the square of the distance
between the centers of the two objects.
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q13. Issac Newton
Universal Law of Gravitation
The gravitational force between two objects is
directly related to the masses of the two objects.
Small Masses
Gravitational Force
Large Masses
The gravitational force is greater between
objects of greater mass.
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q13. Issac Newton
Universal Law of Gravitation
The gravitational force between two objects is
inversely related to the square of the distance
between the two objects
Short Distance
Gravitational Force
Longer Distance
The gravitational force is less between objects
further apart.
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q15. Gravitational phenomena

• Speed of a planet increases as it approaches the
  Sun and decreases when its further away. Why?
• Mercury, closest planet to the sun travels at a
  higher speed in its orbit then other planets.
  Why?

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q15. Gravitational phenomena

• Newton used law of gravitation to calculate the
  masses of the planets from the dimensions of
  their orbits.
• Tides are caused by the moon as it revolves
  around the earth. Why?

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q15. Gravitational phenomena

• Gravitational force explained the long orbits of
  comets and provided proof that they are part of
  the solar system.
• The need to reach a certain speed (escape
  velocity) before leaving the gravitational pull
  of a planet or moon.

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q16. Escape Velocity

• Which planet has the greater mass?

• Which planet requires the greater escape velocity?

• Earth
• 11.2 KM/sec.
• Mars
• 5 KM/sec.

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q16. Escape Velocity

• The minimum velocity needed to escape the
  gravitational pull of a celestial body.
• Escape velocity is directly related to the mass
  of the celestial body.

greater
Escape velocity
less
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q16. Escape Velocity
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