# Chapter 29.1 Structure of the Sun

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Chapter 29.1 Structure of the Sun
Std 1e: Students know the Sun is a typical star and is powered by nuclear reactions, primarily the fusion of hydrogen to form helium. Objective 1: Explain how the sun converts matter into energy in its core Objective 2: Compare the radiative and convective zones of the sun Objective 3: Describe the 3 layers of the sun’s atmosphere

The Sun’s Energy 300,000x larger than Earth
Spectrograph – a device used to break up the sun’s light into a spectrum Used to determine the amount of elements in the Sun

Composition of the Sun Both Hydrogen and Helium occur in the sun 75% of sun’s mass is hydrogen Hydrogen and helium together make up 99% of the sun’s mass

Nuclear Fusion Nuclear fusion - the process by which nuclei of small atoms combine to form a new more massive nucleus Fusion releases huge amounts of energy and has 3 steps: *each step releases energy

Step 1) Two hydrogen nuclei (or protons) collide and fuse.
One proton will become a neutron (release of positron) It is a proton-neutron pair

Step 2) Another proton combines w/ the pair making a 2 proton 1 neutron nucleus

Step 3) Two of these nuclei (2 pro 1 neu) collide and fuse.
2 protons are released. The remaining 2 protons and 2 neutrons fuse forming a helium nucleus

The Final Product Nuclear fusion of 2 hydrogen nuclei combines to produce a helium nucleus The helium nucleus is only 0.7% mass of the hydrogen nucleus from which it formed The lost mass is converted into energy, which causes the sun to shine and it’s high temperature

Mass Changing in Energy
The sun’s energy comes from nuclear fusion The mass lost during fusion becomes energy Subatomic particles are released = Neutrinos

Einstein’s equation (E=mc2) can be used to calculate how mass (or matter) can be converted into energy E = energy produced m = mass or amount of matter c = speed of light (3,000,000km/s) Astronomers used this equation to explain the huge quantities of energy produced by the sun

Objective 1: Explain how the sun converts matter into energy in its core
What provides the sun with its energy? Nuclear fusion What 2 elements make up the sun’s mass? Hydrogen and helium In the equations E = mc2, what does the c represent? Speed of light (3,000,000 km/s)

The Sun’s Interior Has 3 parts: 1) The Core 2) The Radiative Zone
3) The Convection Zone

1] The Core The center of the sun, it’s 25% of sun’s diameter
Temp = 15,000,000 °C – Converts matter into energy!

2] The Radiative Zone The layer surrounding the core
Temps range from 2,000,000-7,000,000 °C. Energy moves outward in the form of electromagnetic waves, or radiation

3] The Convection Zone Surrounding the Radiative Zone
About 2,000,000 °C. Energy in this zone moves by convection As gases move outward from this zone it losses energy, becomes more dense and sinks Therefore, energy is transferred

Objective 2: Compare the radiative and convective zones of the sun
What are the 3 parts of the sun’s interior? Core, convection zone, and radiative zone What is the temperature of the core? 15,000,000 °C How does energy move in the radiative zone? Electromagnetic waves (radiation) What surrounds the radiative zone? Convection zone

The Sun’s Atmosphere Surrounding the Convection Zone is the sun’s atmosphere (the uppermost region of solar gases) The 3 layers are: 1) Photosphere 2) Chromosphere 3) Corona

1] The Photosphere The innermost layer
Made of gases that have risen from the convection zone Much of the energy given off is in the form of visible light, this light is seen from Earth

2] Chromosphere (above the photosphere)
A thin layer of gases From 4,000-50,000 °C. The gases move away from the photosphere forming narrow jets of hot gas that shoot outward

3] The Corona (outermost layer of the atmosphere)
Solar Wind - has a strong magnetic field, electrons and electrically charged particles stream out into space *The chromosphere and the corona can only be seen from Earth during a solar eclipse

Objective 3: Describe the 3 layers of the sun’s atmosphere
What are the 3 layers of the atmosphere? Photosphere, chromosphere and corona What is the innermost layer? Photosphere What is the layer above the photosphere? Chromosphere What has a strong electromagnetic field and electrically charged particles stream into space? Solar winds