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.

Solar PropertiesSolar PropertiesHas more than 99% the mass of our Has more than 99% the mass of our

solar systemsolar systemDiameter: 1,390,000 kmDiameter: 1,390,000 kmMass: 2 x 10Mass: 2 x 103030 kg kgDistance from Earth: 1 AU (150 Distance from Earth: 1 AU (150

million km)million km)Average Density: 1.4 x 10Average Density: 1.4 x 1033 kg/m kg/m33

Rotation period: 25 days (equator); 35 Rotation period: 25 days (equator); 35 days (poles)days (poles)

More Sun FactsMore Sun FactsSurface gravity: 28x times Earth’s Surface gravity: 28x times Earth’s Age: about 5 billion years (middle-Age: about 5 billion years (middle-

aged star)aged star)Solar Composition: mostly Hydrogen Solar Composition: mostly Hydrogen

(70.4%) and Helium (28%)(70.4%) and Helium (28%)Source of energy in core: nuclear Source of energy in core: nuclear

fusion (H fusion (H He) He)E = mcE = mc22 explains how mass is explains how mass is

converted into energyconverted into energy

The Sun’s StructureThe Sun’s StructureCore- sun’s interior; temps may be 15 Core- sun’s interior; temps may be 15

million K; pressures are > than 200 billion million K; pressures are > than 200 billion atmospheresatmospheresNuclear fusion occurs hereNuclear fusion occurs here

Radiative zone- energy transfer by Radiative zone- energy transfer by radiationradiation

Convective zone- convection belts carry Convective zone- convection belts carry energy to sun’s surface; entire process energy to sun’s surface; entire process takes about 20 million yearstakes about 20 million years

Photosphere- lowest layer of Sun’s Photosphere- lowest layer of Sun’s atmosphere; visible surface; avg. temp is atmosphere; visible surface; avg. temp is 5800 K5800 K

Chromosphere- located above Chromosphere- located above photosphere; glows red due to Hydrogen; photosphere; glows red due to Hydrogen; avg. temp is 15,000 K; normally visible avg. temp is 15,000 K; normally visible during total eclipseduring total eclipse

Corona- outermost layer of sun’s Corona- outermost layer of sun’s atmosphereatmosphere

Surface FeaturesSurface FeaturesGranules- bright spots that can be up to Granules- bright spots that can be up to

625 mi across; are the tops of rising 625 mi across; are the tops of rising currents of hot gases; last for about 5 currents of hot gases; last for about 5 minutesminutes

Sunspots- temporary dark, “cool” blotches Sunspots- temporary dark, “cool” blotches on surface of the photosphere; are Earth-on surface of the photosphere; are Earth-sized; avg. temp is 4200 K sized; avg. temp is 4200 K

Sunspot cycle- lasts 11 years; last Sunspot cycle- lasts 11 years; last maximum was 2001-2002maximum was 2001-2002

www.sciencenewsforkids.org

Solar flares- tremendous, explosive Solar flares- tremendous, explosive outburst of particles and radiation from the outburst of particles and radiation from the sun; usually last few minutes; occur near sun; usually last few minutes; occur near sunspots; last large one was April 2001sunspots; last large one was April 2001

Solar prominences- fiery arch of ionized Solar prominences- fiery arch of ionized gas released from the chromosphere; may gas released from the chromosphere; may last a few months; related to sunspotslast a few months; related to sunspots

Solar wind- is a plasma (stream of ions); is Solar wind- is a plasma (stream of ions); is faster, thinner, hotter than any wind on faster, thinner, hotter than any wind on Earth; comes from coronal holesEarth; comes from coronal holes

Coronal holes- less dense regions in sun’s Coronal holes- less dense regions in sun’s corona; weak magnetic fields allow gases corona; weak magnetic fields allow gases to escapeto escape

http://personal.tcu.edu/~mfanelli/imastro/sun

Aurora BorealisAurora Borealis

““Northern lights”Northern lights”Occur when charged particles (ions) from Occur when charged particles (ions) from

the sun disturb Earth’s magnetic field; the the sun disturb Earth’s magnetic field; the particles flow towards Earth along polar particles flow towards Earth along polar magnetic lines; collide w/ N and O atoms magnetic lines; collide w/ N and O atoms in Earth’s ionosphere and produce auroral in Earth’s ionosphere and produce auroral light light

Sun video

OOOHHHHH!! Pretty!!!