Earth's magnetic field overdue a flip -
The discovery by NASA rover Curiosity of evidence that water once flowed on Mars - the most Earth-like planet in the solar system - should intensify interest in what the future could hold for mankind.
The only thing stopping Earth having a lifeless environment like Mars is the magnetic field that shields us from deadly solar radiation and helps some animals migrate, and it may be a lot more fragile and febrile than one might think.
Scientists say earth's magnetic field is weakening and could all but disappear in as little as 500 years as a precursor to flipping upside down.
It has happened before - the geological record suggests the magnetic field has reversed every 250,000 years, meaning that, with the last event 800,000 years ago, another would seem to be overdue.
"Magnetic north has migrated more than 1,500 kilometres over the past century," said Conall Mac Niocaill, an earth scientist at Oxford University. "In the past 150 years, the strength of the magnetic field has lessened by 10 percent, which could indicate a reversal is on the cards."
While the effects are hard to predict, the consequences may be enormous. The loss of the magnetic field on Mars billions of years ago put paid to life on the planet if there ever was any, scientists say.
Mac Niocaill said Mars probably lost its magnetic field 3.5-4.0 billion years ago, based on observations that rocks in the planet's southern hemisphere have magnetisation.
The northern half of Mars looks younger because it has fewer impact craters, and has no magnetic structure to speak of, so the field must have shut down before the rocks there were formed, which would have been about 3.8 billion years ago.
"With the field dying away, the solar wind was then able to strip the atmosphere away, and you would also have an increase in the cosmic radiation making it to the surface," he said.
"Both of these things would be bad news for any life that might have formed on the surface - either wiping it out, or forcing it to migrate into the interior of the planet."
RIGHT HERE, RIGHT NOW
Earth's magnetic field has always restored itself but, as it continues to shift and weaken, it will present challenges - satellites could be more exposed to solar wind and the oil industry uses readings from the field to guide drills.
In nature, animals which use the field could be mightily confused - birds, bees, and some fish all use the field for navigation. So do sea turtles whose long lives, which can easily exceed a hundred years, means a single generation could feel the effects.
Birds may be able to cope because studies have shown they have back-up systems that rely on stars and landmarks, including roads and power lines, to find their way around.
The European Space Agency is taking the issue seriously. In November, it plans to launch three satellites to improve our fairly blurry understanding of the magnetosphere.
The project - Swarm - will send two satellites into a 450 kilometre high polar orbit to measure changes in the magnetic field, while a third satellite 530 kilometres high will look at the influence of the sun.
Read more -
http://www.reuters.com/article/2012/10/03/us-science-earth-magneticfield-idUSBRE8920X620121003
The discovery by NASA rover Curiosity of evidence that water once flowed on Mars - the most Earth-like planet in the solar system - should intensify interest in what the future could hold for mankind.
The only thing stopping Earth having a lifeless environment like Mars is the magnetic field that shields us from deadly solar radiation and helps some animals migrate, and it may be a lot more fragile and febrile than one might think.
Scientists say earth's magnetic field is weakening and could all but disappear in as little as 500 years as a precursor to flipping upside down.
It has happened before - the geological record suggests the magnetic field has reversed every 250,000 years, meaning that, with the last event 800,000 years ago, another would seem to be overdue.
"Magnetic north has migrated more than 1,500 kilometres over the past century," said Conall Mac Niocaill, an earth scientist at Oxford University. "In the past 150 years, the strength of the magnetic field has lessened by 10 percent, which could indicate a reversal is on the cards."
While the effects are hard to predict, the consequences may be enormous. The loss of the magnetic field on Mars billions of years ago put paid to life on the planet if there ever was any, scientists say.
Mac Niocaill said Mars probably lost its magnetic field 3.5-4.0 billion years ago, based on observations that rocks in the planet's southern hemisphere have magnetisation.
The northern half of Mars looks younger because it has fewer impact craters, and has no magnetic structure to speak of, so the field must have shut down before the rocks there were formed, which would have been about 3.8 billion years ago.
"With the field dying away, the solar wind was then able to strip the atmosphere away, and you would also have an increase in the cosmic radiation making it to the surface," he said.
"Both of these things would be bad news for any life that might have formed on the surface - either wiping it out, or forcing it to migrate into the interior of the planet."
RIGHT HERE, RIGHT NOW
Earth's magnetic field has always restored itself but, as it continues to shift and weaken, it will present challenges - satellites could be more exposed to solar wind and the oil industry uses readings from the field to guide drills.
In nature, animals which use the field could be mightily confused - birds, bees, and some fish all use the field for navigation. So do sea turtles whose long lives, which can easily exceed a hundred years, means a single generation could feel the effects.
Birds may be able to cope because studies have shown they have back-up systems that rely on stars and landmarks, including roads and power lines, to find their way around.
The European Space Agency is taking the issue seriously. In November, it plans to launch three satellites to improve our fairly blurry understanding of the magnetosphere.
The project - Swarm - will send two satellites into a 450 kilometre high polar orbit to measure changes in the magnetic field, while a third satellite 530 kilometres high will look at the influence of the sun.
Read more -
http://www.reuters.com/article/2012/10/03/us-science-earth-magneticfield-idUSBRE8920X620121003
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