The Sun 24.3 A typical star powered by nuclear reactions Mostly the (fusion of hydrogen to form helium) Which releases energy

Structure of the sun 1.Solar Atmosphere 2.Solar interior (core)

Solar Interior a)Core - Where nuclear fusion of hydrogen into helium occurs b) Radiation Zone – energy moves outward as electromagnetic radiation c) Convection Zone – Area of convection where energy is being transferred away from the core

The Sun’s interior The sun produces energy by nuclear fusion During nuclear fusion – 4 hydrogen (4.032 atomic mass, 4 X 1.008) are changed (converted) into 1 helium (4.003 atomic mass) – Energy is released – tiny missing mass is converted into energy according to Einstein’s equation

The Sun’s interior cont… each second – Sun consumes ~ 600 million tons of hydrogen – Converting ~ 4 million tons into energy – As hydrogen is consumed, helium is produced forming the solar core Core is continually growing in size ~ 100 billion years of fuel left The sun will remain it’s currents size ~ 10 billion years before it grows in size and eventually consumes Earth

a)Photosphere Layer of gas and is the visible surface of the sun ~ 90% hydrogen ~ 10% helium 500 kilometers thick Appearance of boiling with up and down movements of gas convection of gas transfers energy Tiny amounts of other elements Solar atmosphere

b) Chromosphere Thin red layer of hot gases under low pressure Few thousand kilometers thick Found above the photosphere c) Corona Outermost layer of the solar atmosphere with low density layer of ionized gases  produce solar winds as protons and electrons escape from the gravity of the sun

sunspots Dark areas on the surface of the photosphere Areas with temperatures less than surrounding area # of sunspots varies in an 11 year cycle

Prominences Huge cloudlike arches of gases Solar Flares Explosive outbursts of sudden brightening above sunspot clusters Release high amounts of solar energy  Ultraviolet  Radio  X-ray