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Unformatted text preview: Atmosphere 79% nitrogen, 20% oxygen • Much of the oxygen due to life: photosynthesis o Magnetic field Caused by the outer iron core – currents produce magnetic field Polarity reverses every 300,000 years Traps most of the energetic charged particles from outer space If we didn’t have the magnetic field, these particles would often mutate our cells- wouldn’t be conducive to life on earth o Northern and Southern Lights Produced by charged particles hitting our atmosphere o Tides –Differential forces of the Moon, mostly Force by Moon on Earth • Greatest on near side, smaller on the center, smallest on far side • 2 tides per day, not 1 • Act as if all of the mass were in the center of the Earth Tides separated by about 12 hours Sun doesn’t affect as heavily because it is so much further away • Sun’s differential force is only ½ of the moon’s...
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- Fall '08
- Solar System, Magnetic Field, Planet, rocky outer parts