Published: 1:21PM Wednesday December 17, 2008
Source: Reuters
Source: Reuters/NASAThe Earth's protective magnetosphere has two large holes that are letting in disruptive solar winds
The Earth's protective magnetosphere has two large holes that
are letting in disruptive solar winds, scientists said.
Understanding how these holes form will help them better predict
the electrical storms that cause power grid blackouts and the
aurora, activity that will peak in 2012 as sunspots hit their
maximum level.
Scientists at the American Geophysical Union meeting in San
Francisco said they had been entirely wrong about how solar
particles that cause the storms were entering the Earth's
magnetosphere.
The magnetosphere is a bubble of magnetism that surrounds Earth and
protects us from solar wind.
Scientists once believed that the particles entered when the sun's
magnetic field was aligned opposite to that of the Earth's.
But findings presented at the meeting show that 20 times more
solar particles enter the Earth's magnetic field when it is aligned
in the same direction as the sun's magnetic field.
The alignment causes the two magnetic fields to connect and tears
holes in the Earth's magnetic field over the poles.
"What we observed was the breach in the levee," said Jimmy Raeder,
a physicist at the University of New Hampshire.
"This has taken us completely by surprise."
In June 2007, NASA's five THEMIS spacecraft probes flew through one
of the tears just as it was opening.
Sensors recorded a torrent of solar wind particles streaming
into the magnetosphere, said Raeder.
"The opening was huge - four times wider than Earth itself," said
Raeder.
"This kind of influx is an order of magnitude greater than what
we thought was possible."
Most of the particles are deflected back into space, but some
circulate in the magnetosphere, get energized, and cause electrical
storms that trigger power grid outages, cause problems for aircraft
flying over the poles, and can damage satellites in geosynchronous
orbit.
"There's a bigger risk because we have more stuff in space now,"
said Raeder.
Scientists said that the majority of solar storms take place midway
through and on the tail end of the solar cycle.
This 11-year cycle of activity is at its minimum now and electrical storms will be at their peak in 2012.
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