快猫短视频

HANG on to your compass鈥攖he Earth鈥檚 poles might be starting to flip. So say researchers who鈥檝e seen strange anomalies in our planet鈥檚 magnetic field.

The magnetic field is created by the flow of molten iron inside the Earth鈥檚 core. These circulation patterns are affected by the planet鈥檚 rotation, so the field normally aligns with the Earth鈥檚 axis 鈥攆orming the north and south poles.

But the way minerals are aligned in ancient rock shows that the planet鈥檚 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. They used data from the 脴rsted satellite to study strange variations in the Earth鈥檚 magnetic field. In particular, one large patch under South Africa is pointing in the opposite direction from the rest of the Earth鈥檚 field and has been growing for hundreds of years. The anomalies have already reduced the overall strength of the planet鈥檚 magnetic field by about 10 per cent. If they continue to grow at the same rate, the Earth鈥檚 dipole will disappear within just two millennia.

But 脴rsted is the first satellite to take a snapshot of the Earth鈥檚 magnetic field for 20 years, and such scant data makes it difficult to predict future shifts. 鈥淲e can鈥檛 really tell what will happen,鈥� says Hulot. 鈥淏ut we speculate that we鈥檙e in an unusual situation that might be related to a reversal.鈥�