The surface of the Earth is made of giant tectonic plates that move. As some plates move farther apart, sea floor spreading is observed. At mid-ocean ridges, magma rises from the Earth and solidifies to fill the gap. The Earth’s magnetic field leaves it’s imprint on this material and allows us to examine the direction and magnitude of the magnetic field in the past. Every few hundred thousand years the field changes directions (a compass will point to the South pole instead of the North pole).
Since the 19th century the magnitude of the Earth’s magnetic field has weakened by about 10%. Here is some basic information from NASA on Earth’s Inconstant Magnetic Field. Much research is going on to attempt to understand the Origin of the Earth’s Magnetic Field.
I think the questions on everybody’s mind is what is going to happen in the future and how will it affect us? Some very doomsday scenarios are predicted. I don’t think the end of the world or end of humanity is likely but this is another phenomenon to which we should pay attention.
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