The SUN!. Basic Facts Mass M = 2x10 30 kg = 300,000M E Radius R = 7x10 8 m = 7x10 5 km = 111R E...
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Transcript of The SUN!. Basic Facts Mass M = 2x10 30 kg = 300,000M E Radius R = 7x10 8 m = 7x10 5 km = 111R E...
The SUN!
Basic Facts
• Mass M = 2x1030 kg = 300,000ME
• Radius R = 7x108 m = 7x105 km = 111RE
• Mean Density = Mass/Volume = M/((4/3)R3)= 1400 kg/m3 = 1.4 g/cm3
• Distance = 1.5x1011 m = 1.5x108 km = 8.3 light-minutes
• Luminosity L = 3.9x1026 W (Solar Constant = 1350 W/m2)
• Mean Surface Temperature = Teffective = 5780 K
• Composition By Mass By Number
• H ~68% ~90%
• He ~31%~10%
• “Heavies” ~1% ~1%
The Sun Contains 99.8% of the Mass of the Entire Solar System!
We Rely on the Sun for…
…
• Source of energy• Plants-photosynthesis• Creates wind• Water cycle
The Sun’s Atmosphere
Photosphere
• All elements are gaseous • Get denser as you move toward the core• Photosphere is the “surface” we can see
Granulation
Chromosphere
• Density decreases but temperature increases• Oddity considering the rest of the sun
decreases in temperature as you move away from the core
Spicules
• Flamelike jets of gas that rise up into the chromosphere
The Corona
• Outermost part of the Sun’s atmosphere• Extends millions of miles into space
Reading
Solar Activity
Magnetic Field
Video
• http://www.usatoday.com/story/news/nation-now/2014/01/06/sun-magnetic-field-polarity-reverse/4306845/
Sunspots
• What are they?– Regions marked by lower temperatures– Dark spots on the solar surface
• Cause– Magnetic field exits one and enters the other– Messes up convection in granules and causes
cooling
Structure
• Umbra-dark region• Penumbra-lighter surrounding region
History
• 1610 Sunspots were first observed by Johannes and Fabricius
• 1612 Galileo explained sunspots
How They Are Used
• Rotation of the Sun• Weather?– Low sunspot activity– High sunspot activity
Little Ice Age
• Low solar activity-few sunspots • 1645-1715• Frozen rivers and year-round snow in unlikely
places
Sunspot Cycles
• Cycles every 11 years
Maunder Minimum
• Lowest point of solar activity
Prominences
• Magnetic field redirects the flow of the gases-out one and in the other
Coronal Mass Ejection
• http://csep10.phys.utk.edu/astr162/lect/sun/comet.mpg
• Causes on Earth
Solar Winds
• Flow of charged particles away from the sun• Continual• Greater at coronal holes and less at helmet
streamers
Fusion
• http://www.youtube.com/watch?v=pusKlK1L5To