The Solar System
Sun, Planets, Moons, Asteroids, Comets, Other stuff
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General overview:
Sun is at the center, by far the greatest mass.
Planets and most other parts orbit counter-clock wise, near the ecliptic plane.
Overall radius is about 1 light-year (or 105 AU) from the sun, including distant comets.
Copyright by Bill Arnett, from http://www.seds.org/nineplanets/nineplanets/gif/inner.gif .
When viewed from the outer edge of the planets, the earth's orbit almost vanishes!
Copyright by Bill Arnett, from http://www.seds.org/nineplanets/nineplanets/gif/outer.gif .
The diameters of the planets cover a wide range, from 0.18 to 10.85 times the earth's.
There are two classes of planets: terrestrial and giant (Pluto is neither, and may not even be a planet).
The Sun
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The sun: About 99.9% of the total mass. An ordinary star.
You can look up the masses of all the planets, add them up and convert to grams.
If you divide the total mass of the planets by the mass of the sun, you get less than 0.2%.
Image by NOAO, from http://www.sunspot.noao.edu/gifs/wl.gif
Anatomy of the Sun
Image Copyright by Calvin J. Hamilton, from Views of the Solar System at
http://spaceart.com/solar/eng/homepage.htm
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Photosphere (NASA image from http://www.seds.org/nineplanets/nineplanets/sol.html)
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The visible surface of the sun.
Yellowish light, due to thermal motion of the surface, at 5780 K.
386 billion billion Megawatts of radiated energy.
Sun spots: less hot, less bright areas on the surface.
Appear dark against the bright photosphere.
(NASA image from http://www.seds.org/nineplanets/nineplanets/sol.html)
For example: If Tsunspot = .9 Tsun , how bright is that spot, compared with the sun?
The intensity of light is proportional to T 4. So Bspot / Bsun = (Tspot / Tsun ) 4 .
Thus Bspot / Bsun = (.9) 4 = .66 , which means the spot is 2/3 as bright as the sun.
Sunspots result from twisted magnetic field lines.
Material is raised above the surface, where it cools slightly.
Spots appear in N and S magnetic pairs, one behind the other.
Migrate from upper parts of both hemispheres, toward equator.
Two 11 year cycles, reversing polarities with each cycle.
(NASA image from http://es91-server1.msfc.nasa.gov/ssl/pad/solar/sunspots.htm)
Granules: Cells of material on the surface, about 1000 Km across.
Convection causes them to rise/fall about every 20 minutes.
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(NASA image from http://es91-server1.msfc.nasa.gov/ssl/pad/solar/feature1.htm)
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Supergranules: Larger areas, about 35,000 Km across.
Rise and fall every few days.
(NASA image from http://es91-server1.msfc.nasa.gov/ssl/pad/solar/feature1.htm)
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Solar flares: Large loops of solar material, above the surface.
Pulled up to about half the solar radius by the magnetic field.
Produces lots of solar wind, disrupts radio communications.
(NASA image from http://spaceart.com/solar/cap/sun/sun.htm)
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Solar wind:
Streams of charged ions, moving out at about 250 Km/sec.
Produces Van Allen radiation belts, radio interference, aurora.
(NASA image from http://www.geo.mtu.edu/weather/aurora/images/space/red_aura.gif.)
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Chromosphere
Thin red layer, just above the photosphere.
Visible only with special red filters or during an eclipse.
About 2000 Km thick.
Temperature: 6000 - 10000 K.
Red color comes from a strong emission line of hydrogen.
(NASA image from http://www.athena.ivv.nasa.gov/curric/space/sun/sunanat.html)
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Corona
Blue-white streamers, extending out from the sun about twice Rsun .
Visible only during an eclipse.
Temperature: about 2 Million K.
(HAO image from http://www.hao.ucar.edu:80/public/slides/slide10.html)
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The Core
The
inner part of the sun, about 1/4 of the sun's radius.
Temperature: about 16 Billion K. Pressure: about
billion atmospheres.
Energy is produced by thermonuclear fusion of 4
hydrogens into helium.
core is the only place where temperature and
pressure are high enough for fusion.
Enough energy to last about 10 Billion years. About
Billion years is already gone.
Image Copyright by Calvin J. Hamilton,
from Views of the Solar System at
http://www.spaceart.com/solar/eng/Homepage.htm
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The Radiation Zone
Extends from the core (at .25xRsun), up to .86xRsun.
Temperature reduces from 10 million K to 500,000 K.
Photons of energy from the core ooze up by radiation thru stationary blankets of H and He.
Takes about a million years for the photons to zigzag through all the atoms.
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The Convection Zone
Extends from the radiation zone up to the surface.
Temperature ranges from 500,000 K to 6000 K.
Solar energy is carried by circulating "donuts" of boiling plasma.
Circulation causes large amounts of charged plasma to be stirred around.
Probably creates granulation and supergranluation, and energizes the corona and solar wind.
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The
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The planets (in order of distance from the sun):
o Mercury. The closest to the sun and hottest.
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Venus. Nearest the earth, physically most like the earth.
Copyright by Calvin J. Hamilton.
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Earth. So far, the only confirmed place for life.
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Mars. The red planet. Might be the next place to look for life.
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Jupiter. The most dominant planet, 2.5 times the mass of all other planets, combined.
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Saturn. The most obvious rings and the most satellites.
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Uranus. Spins sideways!
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Neptune. Right side up twin of Uranus.
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Pluto and Charon. Is is a planet? Binary planets?
Asteroids. Small, rocky chunks, mostly between Mars and Jupiter.
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Comets. Rocky snowballs, in large, eccentric, random orbits.
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Meteors. Small rocky fragments which collide with the earth.
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Interplanetary gas and dust.