The Sun

1
The Sun

• Chapter 28

2
Structure of the Sun

• Hydrogen makes up 92 the suns content
• Hydrogen Helium almost 100 of sun
• Three basic regions the core, the inner zones,
  and the atmosphere
• Inner zones and atmosphere are further divided
  into smaller layers
• Boundaries between layers are not distinct

3
Layers of the Sun
4
The Core

• The center of the sun
• Makes up 10 of suns diameter
• Temperature 15,000,000 degrees Celsius
• Made up entirely of gas (liquid and solids cant
  exist at this temperature)
• Mass is 300,000 times greater than the earths
  mass
• Force of gravity is much greater on sun than on
  earth

5
The Core

• Enormous heat and pressure changes structure of
  atoms within core
• Nuclear fusion occurs
• H Pressure Heat Helium Energy

6
The Inner Zones

• Radiative Zone zone surrounding the core
• Temperature 2,500,000 degrees Celsius
• Energy moves from atom to atom in form of
  electromagnetic waves
• Convective zone around the radiative zone
• 1,000,000 degrees Celsius
• Energy produced at core moves through this zone
  by convection (transfer of energy by moving
  liquids or gases)

7
The Suns Atmosphere

• Atmosphere uppermost region of solar gases
  (Three layers)
• Photosphere (innermost layer of the atmosphere)
• Made up of gases bubbling up from the convective
  zone
• Temperature 6,000 degrees Celsius
• Energy given off as visible light
• Considered surface of sun

8
The Suns Atmosphere

• Chromosphere
• Thin layer of gases that glow with a reddish
  light
• Temperature range from 4,000 to 50,000 degrees
  Celsius

9
The Suns Atmosphere

• Corona (Outermost layer of the suns atmosphere)
• Blends into space
• Relatively thick
• prevent most atomic particles from the suns
  surface from escaping
• Some ions and particles do stream out holes in
  corona
• Called solar winds, flow to distant parts of the
  solar system

10
Check Point!

• Describe the most common type of nuclear fusion
  in the sun
• What are the two end products of fusion in the
  sun?
• Will the amount of hydrogen and helium in the sun
  increase or decrease over the next few million
  years?
• What layer of the suns atmosphere can normally
  be seen?

11
Solar Activity

• Sunspots-Cool, dark areas of gas within the
  photosphere that are caused by powerful magnetic
  fields
• Magnetic fields produced by up-and-down movement
  of gases within the suns rotation
• Sunspot Cycle-11 year cycle of sunspots
• Increases for eleven years then decreases
• Movement of sunspots indicates sun rotates on
  axis

12
Prominences and Solar Flares

• Prominences-great clouds of glowing gases that
  form huge arches that reach high above the suns
  surface (Fig. 28.5)
• Solar Flares-sudden outward eruption of
  electrically charged atomic particles
• Magnetic Storm-particles from solar flare flung
  out into space causing sudden disturbance in
  earths magnetic field

13
Auroras

• Auroras-spectacular effect of a magnetic storm
• Electrically charged particles approach the earth
  and are guided toward the earths magnetic pole
  by the magnetosphere
• Particles strike gas molecules in upper
  atmosphere producing green, red, blue, or violet
  sheets of light
• A.K.A Northern Lights or Southern lights
  depending on pole that you observe

14
Check Point!

• How long is the sunspot cycle?
• How are prominences different from solar flares?
• What causes auroras?

15
Formation of the Solar System

• Solar System-includes the sun and the bodies
  revolving around the sun
• Solar Nebular Theory- (Marquis de Leplace)
• The sun and planets condensed out of a spinning
  nebular (cloud of gas and dust)
• Heat from collisions and pressure from gravity
  caused center of solar nebula to become hotter
  and denser
• Hydrogen fusion began and the sun was formed

16
Formation of Planets

• Planetesimals-small bodies of matter in the solar
  nebula
• Planetesimals joined together through collisions
  and through the force of gravity to form larger
  bodies called protoplanets
• Protoplanets condensed into planets and moons
• Distance from sun determines makeup of planets

17
Formation of the Planets

• Four closest planets (Mercury, Venus, Earth and
  Mars)
• Contain heavier elements like iron
• Next four planets (Jupiter, Saturn, Uranus, and
  Neptune)
• Formed in cold regions of the solar nebula
• Icy material of planets mainly frozen gases
• Less dense material

18
The Solid Earth

• As the earth developed denser materials flowed to
  its center
• Three distinct layers formed
• Core-dense composed mostly of iron and nickel
• Mantle-thick layer of rock
• Crust-thin crust of less dense solid material

19
The Atmosphere

• Collisions with earth increased its mass and thus
  its gravity
• Enabled it to capture some hydrogen and helium
  that was abundant in the solar nebula
• First atmosphere lost as result of solar
  explosion or solar wind
• Second Atmosphere resulted from explosion within
  earth (Volcanic eruptions released water vapor,
  carbon dioxide, ammonia and methane)

20
The Atmosphere

• Sunlight caused ammonia and some water vapor to
  change into nitrogen, hydrogen and a little
  oxygen
• Hydrogen very light and escaped into space
• Cyanobacteria and early green plants caused
  oxygen to increase
• Oxygen levels increased to current levels
• Ozone layer-forms shield around earth and its
  inhabitants from harmful ultraviolet radiation of
  the sun

21
The Oceans

• Water Vapor began to condense, it began to fall
  to earth as rain and formed oceans in the lower
  surface areas
• Water absorbs carbon dioxide hence CO2 levels
  lowered in the atmosphere resulting in
  concentrations of chemicals in atmosphere similar
  to what they are now

22
Check Point!

• What two forces caused the solar nebula to
  develop into the sun?
• How were planetesimals different from
  protoplanets?
• What gas in the atmosphere was absorbed by the
  oceans as they formed?
• Explain the following statement Volcanic
  eruptions aid in the creation of an atmosphere.

23
Venus Transit