1. Chapter 28 The Sun
Ch Structure of the Sun

2. The Core 10% of sun’s total diameter of 1,300,000 km.
Core temp. is about 15,000,000 C.
Dense gas, with very strong gravity making the core 10 times denser than iron.
Heat causes electrons to be stripped from core’s atoms…the exposed nuclei can be changed by nuclear fusion.

3. Hydrogen Fusion
Hydrogen protons undergo fusion in a five-step process.
Energy is released during each step in the process.
End result is a helium nucleus.
Mass of helium has about 0.7% less mass than the hydrogen that formed it.
Lost mass was converted to energy.

4. Mass into Energy
Einstein’s theory of relativity proposed that mass and energy were interchangeable according to the formula E=mc2.
E is energy produced.
m is mass.
c is the speed of light, 300,000 km/s.

5. Small amount of matter produces a very large amount of energy.
The sun converts 600 million tons of hydrogen into helium each second.
Other complex fusion reactions occur with nuclei of carbon, nitrogen, and oxygen, producing energy.

6. The Inner Zones
Two zones to pass through before energy produced in the core reaches the sun’s atmosphere.
Radiative Zone—surrounds the core. Energy moves from atom to atom.
Temp. is about 2,500,000 C.
Energy in the form of electromagnetic radiation.

8. Convective Zone—surrounds the radiative zone. Temp. about 1,000,000 C
Energy moves through by convection (heat transfer by moving gases or liquids).
Rising gases transfer heat to the surface.
Gases continuously rise and sink.

10. The Sun’s Atmosphere The three uppermost regions of solar gases.
Photosphere—innermost layer. The layer we see. Temp. about 6000 C. Grainy appearance called granulation due to convecting gases.
Considered the surface of the sun.

12. Chromosphere—layer above the photosphere
Chromosphere—layer above the photosphere. Thin layer that glows with reddish light. Temp. from 4000 to 50,000 C.

14. Corona—outermost layer. Gases blend into space
Corona—outermost layer. Gases blend into space. Heated to about 2,000,000 C by sun’s magnetic field. Prevents most atomic particles from escaping into space. Some do escape through holes, and form the solar wind.
Corona normally not seen, but becomes visible during a solar eclipse.