Monday, 28 April 2014

ASTRONOMY 101: EARTH'S MAGNETOSPHERE


The magnetosphere is a protective field that extends thousands of miles into space. Its magnetism affects everything from global communication to weather patterns. Created by the Earth’s spinning molten core, its existence means that the charged particles of the solar wind are unable to cross the magnetic field lines and are deflected around the Earth towards the poles. This causes beautiful auroras, sometimes appearing far south of their indigenous polar regions, like the recent displays in mid latitude zones.

This life-protecting magnetic field, has decreased by fifteen per cent over the last two centuries. Some scientists think this could be an indication that the Earth’s poles are about to exhibit a long overdue flip. The Earth would be exposed to ozone layer damaging solar winds while power supplies are wiped out, the climate is changed and cancer rates rocket.

A magnetosphere is that area of space, around a planet, that is controlled by the planet's magnetic field. The shape of the Earth's magnetosphere is the direct result of being blasted by solar wind. Image Credit: NASA/Goddard/Aaron Kaase
A recent Danish study concludes that the magnetosphere has far more influence on climate change than carbon dioxide levels, and says the Earth is experiencing a natural period of low cloud cover due to fewer cosmic rays entering the atmosphere.

In November three spacecraft were launched as part of the SWARM mission to uncover the threat of magnetic field change and map it more accurately. Historic evidence shows how dramatically the field has decreased and it appears that every few hundred thousand years the polarity flips so a compass would point south instead of north.

A continued decline of the field over billions of years, would see the Earth looking like Mars, a once oceanic world that has become dry and barren. However, the rate of decline is too fast for the Earth’s core to simply burn out, and it could be the Earth's poles are about to undergo another flip. If this occurs, it would cause the Earth’s magnetic shield to be weakened for thousands of years, opening up our defences and causing cosmic radiation to get through. 

Scientists point out that a magnetic flip would not be a catastrophic, and not all of the effects will be bad. The much sought-after spectacle of an aurora would be visible every night all over the Earth as solar winds hit the atmosphere.

There remains, however, much work yet to be done in understanding the properties of the Earth’s core, and how it generates the magnetosphere.



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