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Article Description:

 

Earth is a huge natural magnet

 

 

 

 

 

 

 

 

 

 

 

 

Earth’s Magnetic Field

Earth is a huge natural magnet. Research has proven the existence of Earth’s magnetic field, whose force extends far out into space, forming an invisible magnetosphere. The magnetosphere protects Earth from the solar wind, a flow of charged radioactive particles from the sun.

 

The Spinning Earth

Like all planets, Earth spins around a central axis with imaginary ends at the north and south poles. This spinning causes the sun to appear to rise and set each day, although the sun actually remains in the center of the solar system.

• Each complete rotation of Earth lasts about 24 hours, producing day and night.

• Earth rotates toward the east, so the sun seems to rise in the east and travel across the sky, setting in the west.

• During summer in the Northern Hemisphere, the North Pole is tilted toward the sun; sunlight falls on much more than half of the Northern Hemisphere.

• This causes the sun to appear to take longer to cross the sky, so the days are longer than the nights.

• During winter in the Northern Hemisphere, the South Pole is tilted toward the sun, so the nights are longer than the days in the Northern Hemisphere.

Drifting Westward

Earth’s magnetic field has magnetic north and south poles. It is the magnetic north pole that exerts a force on a compass needle, causing it to point north. Earth’s magnetic north and south poles are not located at the same places as the geographic North and South poles. The north pole that attracts a magnetic compass is located near Prince of Wales Island in Canada—about 1,600 kilometers (1,000 miles) from the true North Pole. The magnetic south pole is about 2,500 kilometers (1,500 miles) from the true South Pole.

 

Earth’s magnetic field appears to be drifting westward each year. It has been suggested that this westerly drift occurs because the core is rotating eastward a little slower than the outer, more solid parts of Earth.

 

Magnetic Field Reversal

The theory of plate tectonics has provided evidence that Earth’s magnetic field has reversed its polarity many times in the past. The last reversal occurred about a million years ago.

 

During a time of normal polarity, magnetic lines of force leave Earth near the geographic South Pole and reenter near the geographic North Pole. When a magnetic reversal takes place, the magnetic lines of force move in the opposite direction, leaving Earth near the North Pole and entering near the South Pole. In effect, the north magnetic pole and south magnetic pole exchange positions.

 

Many rocks contain an internal record showing the direction of Earth’s magnetic field at the time that the rocks were formed. For example, when the mineral magnetite forms from molten rock, atoms within its crystals respond to Earth’s magnetic field by pointing toward the north magnetic pole. As magnetite cools and hardens into rock, this magnetic record then becomes a permanent feature.

 

 

Earth’s Magnetic Field

• Inside Earth the heat generated by the decay of radioactive elements keeps streams of molten iron flowing through the outer core.

• The flow of molten iron generates electric currents that result in the formation of a magnetic field—similar to the way that electricity flowing through a coil of copper wire creates a magnetic field around the wire.

 

 

 

 

 

 

 

"Earth in Space: Earth’s Magnetic Field ." Southwestern Advantage Online. Southwestern Advantage, 2014. Web. 04 Sep 2014.