1. Topic: The Sun
PSSA: D/S8.D.3.1

2. Objective: TLW describe the characteristics of the layers of the sun.
TLW describe the process by which the sun produces energy.
TLW describe different types of solar activity.

3. MI #1: What is the Sun?
The sun is a large ball of gas (mainly hydrogen and helium) that is held together by gravity and produces energy through the process of nuclear fusion.

4. MI #2: Layers of the Sun
Corona – the outer atmosphere; seen from Earth during total solar eclipses.
Chromosphere – region below the corona; only about 30,000 km thick.
Photosphere – the visible part of the sun that can be seen from Earth

5. MI #3: Layers of the Sun
Convective Zone – a region about 200,000 km thick where gases circulate.
Radiative Zone – dense region that is cooler than the core
Core – the center of the sun; this is where nuclear fusion occurs; temperature can reach 15 million° C.

6. MI #4: Nuclear Fusion
Nuclear fusion is the process by which two low mass nuclei fuse together to form a new nucleus.
Typically this is hydrogen nuclei fusing to form a helium nucleus.

7. MI #5: Sunspots
A sunspot is a cooler, darker region of the photosphere that has a strong magnetic field.
Sunspots appear in cycles; the typical cycle lasts about 11 years.

8. MI #6: Solar Flares
Solar flares are regions of the sun with extremely high temperatures and brightness that send huge streams of electrically charged particles into the solar system.
They are associated with sunspots and can disrupt radio communication on Earth.

9. So What…? Real Life Application
Understanding the sun and nuclear fusion is important because the sun is the Earth’s primary source of energy.