1. Ch. 26.1: Our Sun!

2. Size 1,000,000 Earths could fit inside
contains 99% of the solar system’s mass
Diameter of 1,400,000 km
If the sun were the size of a bottle cap, the largest known star would be the size of a football field!

3. Distance
150,000,000 km away from Earth (average) = 1 Astronomical Unit (AU)
93,000,000 miles
Light, traveling at 300,000 km/s takes 8.5 minutes to reach Earth

4. Energy Fusion of hydrogen (H2) into helium (He) gives sun it’s energy
4 H2 atoms = 1 He atom + energy
Intense heat and pressure causes these atoms to exist in the form of plasma

5. Layers The sun’s temperature decreases from core to surface
From the surface of the sun to the outer atmosphere, the temperature increases
The sun’s layers are heated by convection

6. Sun Layers (cont.) Sun’s Atmosphere Core 15,000,000 Radiative Zone
Layer/Zone
Temperature (°C)
Core
15,000,000
Radiative Zone
8,000,000
Convective Zone
1,500,000
Photosphere
6,000
Chromosphere
20,000
Corona
1,000,000-
3,000,000
Sun
Sun’s
Atmosphere

7. Photosphere (layer 4) surface of the sun
contains features such as sunspots and granules

8. Granules bubbles of hot gas visible on the surface of the sun
1,000 km in diameter
last about 20 minutes

9. Sunspots dark spots on surface of sun cooler than surrounding surface
result from complications in sun’s magnetic field
sunspots go from a min to a max and back to min in 11 year cycles

10. Solar Flares
sudden bursts of energy from the photosphere through the outer atmosphere
rise up suddenly in areas of sunspot activity
number of solar flares increases with the number of sunspots

11. Chromosphere (layer 5) inner layer of atmosphere
thousands of km’s off of surface
contain solar prominences  dense clouds of plasma suspended over surface by magnetic fields

12. Corona (layer 6) thin outer atmosphere
1,000,000 times less bright than photosphere
only visible during solar eclipse
responsible for solar wind

13. Solar Wind
constant stream of electrically charged particles from corona
fly in all directions from sun at 450 km/s
takes 2-3 days to reach Earth
solar flares & wind create auroras on Earth
particles interact with Earth’s magnetic field
Northern and Southern lights

14. Magnetic Storms
occur when solar flares are added to constant solar wind
auroras may be visible at mid-latitudes
electrical surges may disrupt cell phone service & damage electrical appliances