Ch. 26.1: Our Sun!

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!

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

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

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

Layers (cont.)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’sAtmosphere

Photosphere (layer 4)

surface of the sun

contains features such as sunspots and granules

Granules

bubbles of hot gas visible on the surface of the sun

1,000 km in diameter

last about 20 minutes

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

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

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

Corona (layer 6) thin outer

atmosphere

1,000,000 times less bright than photosphere

only visible during solar eclipse

responsible for solar wind

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

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