The Earth, it seems, will be safe when its magnetic field falters during the next reversal of its magnetic poles. A new model of the way the Earth interacts with the solar wind indicates that a replacement field will form in the upper atmosphere during the switch.
Scientists had previously thought that the planet would be left without a protective shield to stop lethal radiation from space reaching the surface.
The strength of the Earth's magnetic field is known to drop during "magnetic reversals", when the north and south poles swap places. Records of the field direction, frozen into sediments laid down on the seabed, show that the magnetic field has reversed hundreds of times in the past 400 million years.
In normal circumstances, the magnetic field protects the Earth's surface from dangerous high-energy particles, including particles from the sun and cosmic rays from deep space.
But as the field switches polarity, it can drop to below 10 per cent of its normal strength for thousands of years. Such a weakened field would allow lethal radiation to reach the Earth's surface, with potentially disastrous consequences for the atmosphere, the climate and particularly for life.
http://www.newscientist.com/news/news.jsp?id=ns99994985
Scientists had previously thought that the planet would be left without a protective shield to stop lethal radiation from space reaching the surface.
The strength of the Earth's magnetic field is known to drop during "magnetic reversals", when the north and south poles swap places. Records of the field direction, frozen into sediments laid down on the seabed, show that the magnetic field has reversed hundreds of times in the past 400 million years.
In normal circumstances, the magnetic field protects the Earth's surface from dangerous high-energy particles, including particles from the sun and cosmic rays from deep space.
But as the field switches polarity, it can drop to below 10 per cent of its normal strength for thousands of years. Such a weakened field would allow lethal radiation to reach the Earth's surface, with potentially disastrous consequences for the atmosphere, the climate and particularly for life.
http://www.newscientist.com/news/news.jsp?id=ns99994985
