Why does the Sun shine?
The Weight of upper layers compress lower layers. The Gravitational equilibrium : gravity pulling in balances pressure pushing out. Also the energy balance : thermal energy released by fusion in core balances radiative energy lost from surface . Lastly the gravitational contraction provided energy that heated the core of the sun.
What is the Sun's structure?
Solar wind: flow of charged particles
Corona: outermost layer of solar atmosphere
Chromosphere: middle layer if solar atmosphere
Photosphere: visible surface of the sun
Convection zone: energy transported upward by rising hot gas
Radiation zone: energy transported upward by photons
Core: energy generated by nuclear fusion
How does nuclear fusion occur in the Sun?
High temps enable nuclear fusion to happen in the core . The sun releases energy by fusing four hydrogen nuclei into one helium nucleus. Proton-proton chain is how hydrogen fuses into helium in the sun.
How does the energy from fusion get out of the Sun?
Energy gradually leaks out of the radiation zone in the form of randomly bouncing photons. Also convection (rising hot gas) energy to the surface.
How do we know what is happening inside the Sun?
By Making mathematical models, Observing solar vibrations and Observing solar neutrinos.
What causes solar activity?
The solar activity is like "weather" on earth. Also sunspots, which are cooler than other parts of the sun's surface (4000K). Solar Flares are regions with strong magnetic fields.
How does solar activity vary with time?
The number is sunspots rises and falls in 11 year cycles. The sunspot cycle has something to do with the winding and twisting of the sun's magnetic field.
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