Sloshing Inside Earth Changes Protective Magnetic Field
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Oct 20, 2009, 2:36:41 AM10/20/09
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Sloshing Inside Earth Changes Protective Magnetic Field
Jeremy Hsu
Staff Writer
SPACE.com Mon Aug 18, 6:45 AM ET
Something beneath the surface is changing Earth's protective magnetic
field, which may leave satellites and other space assets vulnerable
to high-energy radiation.
The gradual weakening of the overall magnetic field can take hundreds
and even thousands of years. But smaller, more rapid fluctuations
within months may leave satellites unprotected and catch scientists
off guard, new research finds.
A new model uses satellite data from the past nine years to show how
sudden fluid motions within the Earth's core can alter the magnetic
envelope around our planet. This represents the first time that
researchers have been able to detect such rapid magnetic field
changes taking place over just a few months.
"There are these changes in the South Atlantic, an area where the
magnetic field has the smallest envelope at one third [of what is]
normal," said Mioara Mandea, a geophysicist at the GFZ German
Research Center for Geosciences in Potsdam, Germany.
Even before the newly detected changes, the South Atlantic Anomaly
represented a weak spot in the magnetic field — a dent in Earth's
protective bubble.
Bubble bobble
The Earth's magnetic field extends about 36,000 miles (58,000 km)
into space, generated from the spinning effect of the electrically-
conductive core that acts something like a giant electromagnet. The
field creates a tear-drop shaped bubble that has constantly shielded
life on Earth against much of the high-energy radiation flowing from
the sun.
The last major change in the field took place some 780,000 years ago
during a magnetic reversal, although such reversals seem to occur
more often on average. A flip in the north and south poles typically
involves a weakening in the magnetic field, followed by a period of
rapid recovery and reorganization of opposite polarity.
Some studies in recent years have suggested the next reversal might
be imminent, but the jury is out on that question.
Measuring interactions between the magnetic field and the molten iron
core 1,864 miles (3,000 km) down has proven difficult in the past,
but the constant observations of satellites such as CHAMP and Orsted
have begun to bring the picture into focus.
Electric storm
Mandea worked with Nils Olsen, a geophysicist at the University of
Copenhagen in Denmark, to create a model of the fluid core that fits
with the magnetic field changes detected by the satellites.
However, the rapid weakening of the magnetic field in the South
Atlantic Anomaly region could signal future troubles for such
satellites. Radiation storms from the sun could fry electronic
equipment on satellites that suddenly lacked the protective cover of
a rapidly changing magnetic field.
"For satellites, this could be a problem," Mandea told SPACE.com. "If
there are magnetic storms and high-energy particles coming from the
sun, the satellites could be affected and their connections could be
lost."
The constant radiation bombardment from the sun blows with the solar
wind to Earth, where it flows against and around the magnetic field.
The effect creates the tear-drop shaped magnetosphere bubble, but
even the powerful field cannot keep out all the high-energy particles.
Topsy-turvy history
A large sunspot set off a major radiation storm in 2006 that
temporarily blinded some sun-watching satellites. Astronauts on the
International Space Station retreated to a protected area as a
precaution to avoid unnecessary radiation exposure.
The Earth's overall magnetic field has weakened at least 10 percent
over the past 150 years, which could also point to an upcoming field
reversal.
Mandea and Olsen hope to continue refining their model with updated
observations, and perhaps to eventually help predict future changes
in the Earth's magnetic field.
The study was detailed in the May online edition of the journal
Nature Geoscience.
Top Ten Strangest Things in Space
Top Ten Unexplained Phenomena
101 Amazing Earth Facts
Original Story: Sloshing Inside Earth Changes Protective Magnetic
Field
SPACE.com offers rich and compelling content about space science,
travel and exploration as well as astronomy, technology, business
news and more. The site boasts a variety of popular features
including our space image of the day and other space pictures,space
videos, Top 10s, Trivia, podcasts and Amazing Images submitted by our
users. Join our community, sign up for our free newsletters and
register for our RSS Feeds today!
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http://news.yahoo.com/s/space/20080818/sc_space/sloshinginsideearthcha
ngesprotectivemagneticfield
Jeremy Hsu
Staff Writer
SPACE.com Mon Aug 18, 6:45 AM ET
Something beneath the surface is changing Earth's protective magnetic
field, which may leave satellites and other space assets vulnerable
to high-energy radiation.
The gradual weakening of the overall magnetic field can take hundreds
and even thousands of years. But smaller, more rapid fluctuations
within months may leave satellites unprotected and catch scientists
off guard, new research finds.
A new model uses satellite data from the past nine years to show how
sudden fluid motions within the Earth's core can alter the magnetic
envelope around our planet. This represents the first time that
researchers have been able to detect such rapid magnetic field
changes taking place over just a few months.
"There are these changes in the South Atlantic, an area where the
magnetic field has the smallest envelope at one third [of what is]
normal," said Mioara Mandea, a geophysicist at the GFZ German
Research Center for Geosciences in Potsdam, Germany.
Even before the newly detected changes, the South Atlantic Anomaly
represented a weak spot in the magnetic field — a dent in Earth's
protective bubble.
Bubble bobble
The Earth's magnetic field extends about 36,000 miles (58,000 km)
into space, generated from the spinning effect of the electrically-
conductive core that acts something like a giant electromagnet. The
field creates a tear-drop shaped bubble that has constantly shielded
life on Earth against much of the high-energy radiation flowing from
the sun.
The last major change in the field took place some 780,000 years ago
during a magnetic reversal, although such reversals seem to occur
more often on average. A flip in the north and south poles typically
involves a weakening in the magnetic field, followed by a period of
rapid recovery and reorganization of opposite polarity.
Some studies in recent years have suggested the next reversal might
be imminent, but the jury is out on that question.
Measuring interactions between the magnetic field and the molten iron
core 1,864 miles (3,000 km) down has proven difficult in the past,
but the constant observations of satellites such as CHAMP and Orsted
have begun to bring the picture into focus.
Electric storm
Mandea worked with Nils Olsen, a geophysicist at the University of
Copenhagen in Denmark, to create a model of the fluid core that fits
with the magnetic field changes detected by the satellites.
However, the rapid weakening of the magnetic field in the South
Atlantic Anomaly region could signal future troubles for such
satellites. Radiation storms from the sun could fry electronic
equipment on satellites that suddenly lacked the protective cover of
a rapidly changing magnetic field.
"For satellites, this could be a problem," Mandea told SPACE.com. "If
there are magnetic storms and high-energy particles coming from the
sun, the satellites could be affected and their connections could be
lost."
The constant radiation bombardment from the sun blows with the solar
wind to Earth, where it flows against and around the magnetic field.
The effect creates the tear-drop shaped magnetosphere bubble, but
even the powerful field cannot keep out all the high-energy particles.
Topsy-turvy history
A large sunspot set off a major radiation storm in 2006 that
temporarily blinded some sun-watching satellites. Astronauts on the
International Space Station retreated to a protected area as a
precaution to avoid unnecessary radiation exposure.
The Earth's overall magnetic field has weakened at least 10 percent
over the past 150 years, which could also point to an upcoming field
reversal.
Mandea and Olsen hope to continue refining their model with updated
observations, and perhaps to eventually help predict future changes
in the Earth's magnetic field.
The study was detailed in the May online edition of the journal
Nature Geoscience.
Top Ten Strangest Things in Space
Top Ten Unexplained Phenomena
101 Amazing Earth Facts
Original Story: Sloshing Inside Earth Changes Protective Magnetic
Field
SPACE.com offers rich and compelling content about space science,
travel and exploration as well as astronomy, technology, business
news and more. The site boasts a variety of popular features
including our space image of the day and other space pictures,space
videos, Top 10s, Trivia, podcasts and Amazing Images submitted by our
users. Join our community, sign up for our free newsletters and
register for our RSS Feeds today!
Email Story
IM Story
Printable View
http://news.yahoo.com/s/space/20080818/sc_space/sloshinginsideearthcha
ngesprotectivemagneticfield
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