Magnetic Versus Geographic Poles and Precession
What causes Earth's Magnetic Field?
ð Spinning on axis
ð Earth's core: solid inner, liquid
outer, mantle
Geographic versus Magnetic Poles.
ð Geographic: Axis
of rotation
ð Magnetic: Field lines are vertical
Precession of the Earth
ð One revolution
every 26,000 years
ð North star changes
Reversal of Poles
ð Swapping of pole
locations
ð In the past 3.6 million years we believe there have
been at least 9 reversals
Declination angles
ð Angle
between geographic and magnetic poles
ð Varies
from 0 to 20 degrees depending on location.
ð Navigation
maps must be adjusted accordingly.
Rotation About Axis
Counterclockwise looking down on N Pole - about 1000 mph at the
equator
Rotation About the Sun About 67,000 mph |
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Earth's Poles
Geographic Versus Magnetic |
Precession
of Earth's Rotation Axis |
