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Anomalies hint at magnetic pole flip
From: Derrick Young
Date: 2002 Apr 12, 11:26 -0400
From: Derrick Young
Date: 2002 Apr 12, 11:26 -0400
don't know how many of you are aware of this - makes interesting reading - and another good reason to study/practice CELNAV. This is from the New Scientist (a British publication) - http://www.newscientist.com/news/news.jsp?id=ns99992152 derrick Anomalies hint at magnetic pole flip 19:00 10 April 02 Exclusive from New Scientist-The Earth's magnetic poles might be starting to flip say researchers who have seen strange anomalies in our planet's magnetic field. The magnetic field is created by the flow of molten iron inside the Earth's core. These circulation patterns are affected by the planet's rotation, so the field normally aligns with the Earth's axis - forming the north and south poles. But the way minerals are aligned in ancient rock shows that the planet's magnetic dipole occasionally disappears altogether, leaving a much more complicated field with many poles all over the planet. When the dipole comes back into force, the north and south poles can swap places. The last reversal happened about 780,000 years ago, over a period of several thousand years. Now Gauthier Hulot from the Institute of Earth Sciences in Paris and his colleagues think they have spotted early signs of another reversal. South African anomaly They used data from the �rsted satellite to study strange variations in the Earth's magnetic field. In particular, one large patch under South Africa is pointing in the opposite direction from the rest of the Earth's field and has been growing for hundreds of years. The anomalies have already reduced the overall strength of the planet's magnetic field by about 10 per cent. If they continue to grow at the same rate, the Earth's dipole will disappear within just two millennia. But �rsted is the first satellite to take a snapshot of the Earth's magnetic field for 20 years, and such scant data makes it difficult to predict future shifts. "We can't really tell what will happen," says Hulot. "But we speculate that we're in an unusual situation that might be related to a reversal." Journal reference: Nature (vol 416, p 620)
