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

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

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