Sun
The The Sun
Solar Characteristics Solar Structure Solar Features Sunspot Cycles Magnetosphere
Sun
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
One
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 Characteristics Solar Structure Solar Features Sunspot Cycles Magnetosphere
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 proton-proton reaction
Four hydrogen nuclei are converted into a helium nuclei Matter is converted to energy 600 million tons of hydrogen is consumed each second
Sun has enough fuel to last another five billion years
Hydrogen fusion in the core
Solar Interior
Solar cross-section 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 the at top exceeds 1 million K
A quiet solar corona
Solar temperatures rise in the corona
The Sun
Solar Characteristics Solar Structure Solar Features Sunspot Cycles Magnetosphere
Sun
Solar features
Plages
Bright centers of solar activity Occur above sunspot clusters Huge arching cloudlike structures that extend into the corona Condensations of material in the corona
Prominences
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 11-year cycle Large spots are strongly magnetized Pairs have opposite magnetic poles
Umbra and penumbra of a typical sunspot
The Sun
Solar Characteristics Solar Structure Solar Features Sunspot Cycles Magnetosphere
Sunspot Cycles
Maunder Minimum
Maunder minimum associated with the "little ice age"
Patterns of Sunspot Cycles
The Sun
Solar Characteristics Solar Structure Solar Features Sunspot Cycles Magnetosphere
Solar Rotation
Solar Rotation
Equatorial rotation is 24 days Polar rotation is 27 days
Sunspots
Close-up 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