Solar Properties Has more than 99% the mass of our solar system Has more than 99% the mass of our solar system Diameter: 1,390,000 km Diameter: 1,390,000 km Mass: 2 x kg Mass: 2 x kg Distance from Earth: 1 AU (150 million km) Distance from Earth: 1 AU (150 million km) Average Density: 1.4 x 10 3 kg/m 3 Average Density: 1.4 x 10 3 kg/m 3 Rotation period: 25 days (equator); 35 days (poles) Rotation period: 25 days (equator); 35 days (poles)

More Sun Facts Surface gravity: 28x times Earth’s Surface gravity: 28x times Earth’s Age: about 5 billion years (middle- aged star) Age: about 5 billion years (middle- aged star) Solar Composition: mostly Hydrogen (70.4%) and Helium (28%) Solar Composition: mostly Hydrogen (70.4%) and Helium (28%) Source of energy in core: nuclear fusion (H  He) Source of energy in core: nuclear fusion (H  He) E = mc 2 explains how mass is converted into energy E = mc 2 explains how mass is converted into energy

The Sun’s Structure Core- sun’s interior; temps may be 15 million K; pressures are > than 200 billion atmospheres Core- sun’s interior; temps may be 15 million K; pressures are > than 200 billion atmospheres Nuclear fusion occurs here Nuclear fusion occurs here Radiative zone- energy transfer by radiation Radiative zone- energy transfer by radiation Convective zone- convection belts carry energy to sun’s surface; entire process takes about 20 million years Convective zone- convection belts carry energy to sun’s surface; entire process takes about 20 million years

Photosphere- lowest layer of Sun’s atmosphere; visible surface; avg. temp is 5800 K Photosphere- lowest layer of Sun’s atmosphere; visible surface; avg. temp is 5800 K Chromosphere- located above photosphere; glows red due to Hydrogen; avg. temp is 15,000 K; normally visible during total eclipse Chromosphere- located above photosphere; glows red due to Hydrogen; avg. temp is 15,000 K; normally visible during total eclipse Corona- outermost layer of sun’s atmosphere Corona- outermost layer of sun’s atmosphere

Surface Features Granules- bright spots that can be up to 625 mi across; are the tops of rising currents of hot gases; last for about 5 minutes Granules- bright spots that can be up to 625 mi across; are the tops of rising currents of hot gases; last for about 5 minutes Sunspots- temporary dark, “cool” blotches on surface of the photosphere; are Earth- sized; avg. temp is 4200 K Sunspots- temporary dark, “cool” blotches on surface of the photosphere; are Earth- sized; avg. temp is 4200 K Sunspot cycle- lasts 11 years; last maximum was Sunspot cycle- lasts 11 years; last maximum was

Solar flares- tremendous, explosive outburst of particles and radiation from the sun; usually last few minutes; occur near sunspots; last large one was April 2001 Solar flares- tremendous, explosive outburst of particles and radiation from the sun; usually last few minutes; occur near sunspots; last large one was April 2001 Solar prominences- fiery arch of ionized gas released from the chromosphere; may last a few months; related to sunspots Solar prominences- fiery arch of ionized gas released from the chromosphere; may last a few months; related to sunspots Solar wind- is a plasma (stream of ions); is faster, thinner, hotter than any wind on Earth; comes from coronal holes Solar wind- is a plasma (stream of ions); is faster, thinner, hotter than any wind on Earth; comes from coronal holes Coronal holes- less dense regions in sun’s corona; weak magnetic fields allow gases to escape Coronal holes- less dense regions in sun’s corona; weak magnetic fields allow gases to escape

Aurora Borealis “Northern lights” “Northern lights” Occur when charged particles (ions) from the sun disturb Earth’s magnetic field; the particles flow towards Earth along polar magnetic lines; collide w/ N and O atoms in Earth’s ionosphere and produce auroral light Occur when charged particles (ions) from the sun disturb Earth’s magnetic field; the particles flow towards Earth along polar magnetic lines; collide w/ N and O atoms in Earth’s ionosphere and produce auroral light Sun video Sun video Sun video Sun video

OOOHHHHH!! Pretty!!!