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Magnetosphere (magnetic field)

Magnetosphere (magnetic field). Convection of liquid metals in the outer core creates the Earth's magnetic field. Extends outward from the Earth for several thousand kilometers

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Magnetosphere (magnetic field)

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  1. Magnetosphere (magnetic field) Convection of liquid metals in the outer core creates the Earth's magnetic field. Extends outward from the Earth for several thousand kilometers Deflects the Sun's solar wind. Without this field, the solar wind would directly strike the Earth's atmosphere. This could potentially have removed the Earth's atmosphere, rendering it nearly lifeless, as is hypothesized for Mars.

  2. Earth’s Magnetic Field • Earth is a giant dipole magnet • Magnetic poles are very close to the geographic poles • May result from different rotation speeds of outer core and mantle

  3. Polar Wandering In the 1950’s, research showed that the poles had been in different positions in the past. The apparent movement was called polar wandering. The best explanation for this movement is that the poles are stationary, and the continents moved.

  4. “Polar Wandering” * Further evidence for plate tectonics Misnomer - The magnetic poles haven’t moved…. the plates have moved.

  5. Magnetic Reversals • Earth’s present magnetic field is called normal. Magnetic north is near geographic north. • At various times in the past, Earth’s magnetic field has completely reversed, with magnetic south near the north geographic pole. This is referred to as a magnetic reversal.

  6. Magnetic Reverals • North magnetic pole switches with South magnetic pole • 4-5 during the last 10 my • No idea when it will flip again

  7. Magnetic Reversals • Measuring paleomagnetism and dating continental lava flows led to • the realization that magnetic reversals existed • the establishment of a magnetic reversal time scale

  8. What makes the Earth a magnet? Dynamo Theory: • magnetic field generation requires: - Rapid Rotation - Metal (electrical conductor) - Liquid Core

  9. Will a compass lead you directly to the geographic North Pole???

  10. Van Allen Belts - • Two regions surrounding Earth that capture high-energy charged particles • Particles originate in solar wind

  11. a) outer belt - contains mostly lighter electrons b) inner belt contains heavier protons

  12. We’d die in the Van Allen Belts

  13. Charged particles escape Van Allen belts near the North and South magnetic poles

  14. Charged particles then collide with air molecules, get excited, then… => Produce spectacular light show called AURORA

  15. “Northern Lights”

  16. more pics

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