Sun and Seasons

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Movie at http://sohowww.nascom.nasa.gov/bestofsoho/Movies/dynamo/dynamosm.mpg

Slide 10

Inside the Sun

Core

Radiative Zone

Convection zone

Image at http://solarscience.msfc.nasa.gov/interior.shtml

Slide 11

The Sun’s Atmosphere

Photosphere

Chromosphere

Corona

Photosphere image: http://science.msfc.nasa.gov/ssl/pad/solar/surface.htm

Chromosphere image: http://science.msfc.nasa.gov/ssl/pad/solar/chromos.htm

Corona image: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=191

Slide 12

Energy from the Sun

Nuclear chain reaction (hydrogen forming helium)

Releases radiation (gamma rays)

The gamma ray loses energy as it bounces around inside the Sun

It is finally released at the photosphere, primarily as visible light

Slide 13

Features in the Photosphere

Sunspots

Dark and small (but brighter than Full Moon and big as Earth)

Cool-- temperatures only 6,200 F (Sun’s surface is 10,000 F)

Associated with magnetic fields: one set of spots is positive, other is negative

Image at http://sohowww.nascom.nasa.gov/gallery/top10/top10_results.html

Slide 14

More on Sunspots

Our Sun has an activity cycle of 11 years

Sunspots appear at specific latitudes on Sun

Bands of latitude move towards equator during cycle

Slide 15

Solar Events

Flares (Explosions of energy on the surface of the Sun)

Prominences

Coronal Mass Ejections (massive clouds of plasma ejected from the Sun)

Movie: Six months with EIT 171 (Aug. 12, 2003 - Feb. 9, 2004)

Slide 16

Solar Wind

Blows charged particles and magnetic fields away from the Sun

Charged particles captured by Earth’s magnetic field

Create Auroras or Northern and Southern Lights

Slide 17

Auroras

Electrons from solar wind are captured by the Earth’s magnetic field

Interact with atoms in our atmosphere: oxygen and nitrogen make red and green; nitrogen can also make violet

Northern lights are Aurora Borealis, while southern are Aurora Australis

Animation of solar wind impacting the magnetosphere and creating aurora

Slide 18

Coronal Mass Ejection