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Unformatted text preview: The Sun The Sun Solar Structure Solar Features Sunspot Cycles Magnetosphere Solar Characteristics Sun One of 200 billion stars that make up the Milky Way galaxy Only star close enough to allow the surface features to be studied An average star Composition of the Sun Hydrostatic Equilibrium Oscillating solar vibrations Interior movements may be deduced by monitoring surface oscillations. Downward moving gases (red) and up (blue). The Sun Solar Structure Solar Features Sunspot Cycles Magnetosphere Solar Characteristics Sun
Structure can be divided into five parts Core Atmosphere Photosphere Chromosphere Corona Core Nuclear fusion occurs here Nuclear reaction that produces the Sun's energy is called the protonproton reaction Sun has enough fuel to last another five billion years Four hydrogen nuclei are converted into a helium nuclei Matter is converted to energy 600 million tons of hydrogen is consumed each second Hydrogen fusion in the core Solar Interior Solar crosssection with corresponding graphs of: Density Temperature Atmosphere Consists of two parts: Radiation Zone 7,000,000 degrees Kelvin Energy movement by electromagnetic radiation Convection Zone 2,000,000 degrees Kelvin Energy movement by convection Solar Convection Transport of energy in the upper atmosphere is described as a seething sea of gas. Photosphere "Sphere of light" Sun's "surface" actually a layer of incandescent gas less than 500 kilometers thick Grainy texture made up of many small, bright markings, called granules, produced by convection Temperature averages approximately 5800 K (10,000F) Granules of the solar photosphere Photosphere Convective gases on the photosphere Each cell about the size of Texas Chromosphere Just above photosphere Literally the "color layer" Relatively thin, hot layer of incandescent gases a few thousand kilometers thick Top contains numerous spicules narrow jets of rising material The solar structure Spicules of the chromosphere Chromosphere Thin jets of gas Cannot escape the pull of gravity to create the solar wind Chromosphere Faint light of the chromosphere during a total solar eclipse Corona Outermost portion of the solar atmosphere Very tenuous Ionized gases escape from the outer fringe and produce the solar wind Temperature at the top exceeds 1 million K A quiet solar corona Solar temperatures rise in the corona The Sun Solar Structure Solar Features Sunspot Cycles Magnetosphere Solar Characteristics Sun Solar features Plages Prominences Bright centers of solar activity Occur above sunspot clusters Huge arching cloudlike structures that extend into the corona Condensations of material in the corona Solar Prominences A huge solar prominence Solar Prominences Ionized gases follow magnetic field lines Temperatures about 1 million degrees K Sun Solar features Flares Explosive events that normally last an hour or so Sudden brightening above a sunspot cluster Release enormous quantities of energy Eject particles that reach Earth in about one day and interact with the atmosphere to cause the auroras (the Northern and Southern Lights) Solar Flare A violent explosion and ejection of solar matter into space. Hot solar gases break free of the magnetic field confining it and bursts into space. Sunspots On the solar surface Dark center, the umbra, surrounded by a lighter region, the penumbra Dark color is due to a cooler temperature (1500 K less than the solar surface) Follow an 11year cycle Large spots are strongly magnetized Pairs have opposite magnetic poles Umbra and penumbra of a typical sunspot The Sun Solar Structure Solar Features Sunspot Cycles Magnetosphere Solar Characteristics Sunspot Cycles Maunder Minimum Maunder minimum associated with the "little ice age" Patterns of Sunspot Cycles The Sun Solar Structure Solar Features Sunspot Cycles Magnetosphere Solar Characteristics Solar Rotation Solar Rotation Equatorial rotation is 24 days Polar rotation is 27 days Sunspots Closeup of a sunspot pair Earth sized sunspot Appears dark because the temperature is 1500 K cooler than surrounding photosphere Creation of Solar Wind Coronal Mass Ejection Occurs a few times weekly. A magnetized "bubble" of solar material detaches from the sun. The Sun end of chapter Total Solar Eclipse, Mexico 1991 Active and irregular corona during sunspot maximum Caused by prominences and flares on the solar surface Neutrino Telescope 13,000 light detectors 50,000 tons of purified water Neutrinos are ejected from sun during hydrogen fusion Sunspots The Solar Realm ...
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- Summer '07