1. The Sun
Section 26.1

2. Energy From the Sun
The sun gives off huge amounts of electromagnetic radiation which can be used for energy.
How does the sun produce energy?
-In the central region by the fusion of hydrogen nuclei into helium nuclei.

3. Forces in Balance
The sun has been a mainly stable source of energy for the Earth for billions of years.
The sun must be in equilibrium in relation to the inward and outward forces for it to be stable.
Temperature, pressure, and density at any depth remain constant over time.

4. Forces in Balance (cont.)
The sun remains stable because the inward pull of gravity balances the outward push of thermal pressure from nuclear fusion.
The sun will remain stable as long as there is a stable energy source within it.

5. The Sun’s Interior
Can you see inside the sun? Astronomers use math models and observe vibrations that are similar to earthquakes on Earth to determine the Sun’s inside.
Suns interior consists of the core, radiation zone, and convection zone.

6. The Sun’s Interior (cont.)
Core- Central region, where nuclear fusion occurs. It’s diameter is 400,000 kilometers.
Radiation Zone- Region of highly compressed gas. Energy is transferred by the absorption and radiation of electromagnetic waves.

7. The Sun’s Interior (cont.)
FACT: Energy takes more than 100,000 light years to pass through it.
1 light year = 5,878,000,000,000 miles.
Light years are the distance light can travel in a vacuum.
Convection Zone- Outer layer of the sun’s interior. Energy from the radiation zone passes through here.

8. The Sun’s Atmosphere
Outside the convection zone is the suns atmosphere.
3 Layers
1) Photosphere- Innermost layer. Not solid, called the sun’s surface. Bubbly appearance.
2) Chromosphere- Middle layer. High temperature and emits a reddish light.
3) Corona- Outermost layer of the sun’s atmosphere. Extends millions of kilometers above chromosphere.

9. Solar Wind
The gases of the corona thin out into the solar wind, a stream of electrically charged particles.
These particles flow outward from the sun through the solar system.

10. Solar Wind (cont.)
The Earth’s magnetic fields deflects these particles, but enter near the poles and produce auroras.

11. The Sun

12. Features of the Sun’s Atmosphere
1) Sunspots- Areas of gas in the photosphere that are cooler than the surrounding gases. Small, dark looking regions on the sun’s surface.
2) Prominences- Huge loops of gas that erupt from sunspot regions. Some reach heights of 100,000 kilometers.
3) Solar Flares- A sudden release of energy from the sun. Temperatures reach 20 million Kelvin.