The Sun The interior of the sun has three layers: the core, where energy is produced by nuclear fusion the radiative zone, where energy is transported by radiation the convection zone, where energy is transported by convection

Layers The Core The center of the sun, where the energy is produced, 27,000,000 ° F, approximately 347,500 km thick

Layers Radiative Zone Very dense, about 300,000 km thick

Layers Convective Zone About 200,000 km thick where gases circulate

Layers Photosphere The visible part (but not solid) we can see from Earth that is about 100 km thick.

Layers Chromosphere A thin, irregular region just below the corona, only 30,000 km thick

Layers Corona The sun’s outer layer, anywhere from 10 km to 100,000 km thick

The Sun’s Basic Layers

Features in the Photosphere Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Solar Events Flares (Explosions of energy on the surface of the Sun) Prominences Coronal Mass Ejections (massive clouds of plasma ejected from the Sun) Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Coronal Mass Ejection The eruption of a huge bubble of hot gas from the Sun This series of images of coronal mass ejections taken with LASCO C3 (May 1-31, 1997) at http://sohowww.nascom.nasa.gov/bestofsoho/Movies/C3May97/C3May97sm.mpg Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 CME’s effects on Earth Can damage satellites Very dangerous to astronauts Power problems Animation of a CME leaving the Sun, slamming into our magnetosphere. http://sohowww.nascom.nasa.gov/bestofsoho/Movies/recon/reconsm.mpg Lunar and Planetary Institute