Breathtaking Images of Astral Auroras
Auroral activity results from atomic particles spiralling into the earth's north and south polar atmosphere along magnetic field lines and then colliding with atmospheric molecules. The earth's magnetic field flips its poles every few thousand years and the present weakening of the field seems to indicate the approach of a field flip. Reuters

Going by data collected by the European Space Agency (ESA) satellite array Swarm, the earth's magnetic field may flip sooner than predicted earlier. The present data suggests the magnetic north is moving toward Siberia.

The data shows the earth's magnetic field, which extends 600,000 kms above the surface, has been weakening over the past six months, even though not uniformly. The most likely reason for this weakening is believed to be the magnetic flip cycle. Earth's magnetic field has flipped many times over in the last billion years.

The biggest weak spots in the magnetic field as recorded by magnetometers aboard Swarm were over the Western Hemisphere, while it has strengthened over areas like the southern Indian Ocean.

"Such a flip is not instantaneous, but will take many hundreds, if not a few thousand years," Rune Floberghagen, Swarm mission manager told Live Science.

What the data from Swarm shows is that the magnetic field is weakening faster than in the past. Previous estimates revealed the field was weakening about 5% per century, but the latest data shows a weakening at 5% per decade.

In essence, this means the full flip could occur sooner than the 2,000 years it was expected to take.

Every 11 years, at the peak of the 11-year solar cycle, the sun's magnetic polarity also reverses. Earth's magnetic field reversals happen much less frequently. The time between geomagnetic reversals can vary, and is not known accurately, but the average time between reversals appears to be in the order of hundreds of thousands of years.

However, there have been no evidence of danger to life or radiation damage during previous polarity flips. At the worst, power grids and communication systems could be affected. Unlike on the sun, Earth's magnetic field will not go to zero when it reverses.

The earth's magnetic field acts like a giant invisible bubble that shields the planet from the dangerous cosmic radiation from the sun and the space beyond. The field exists because Earth has a giant ball of iron at its core surrounded by an outer layer of molten metal. Owing to the change in the core's temperature accompanied by the earth's rotation, the magnetic field lines are created in the outer core.