Earth is a Giant Magnet

Geospace
Look out star warriors and trekkers, Earth has its own protective force field -- the magnetosphere. Our planet's magnetic field extends tens of thousands of miles into space where it deflects the solar wind and other particle radiation away from Earth.

The gusty solar wind and CMEs buffet and distort Earth's magnetosphere, sometimes causing magnetic storms. Fortunately, our magnetic cocoon and atmosphere shelter us from the explosions of energy from the Sun.
Earth -- In the Path of the Storm
The Auroral Corona [Jan Curtis]
The aurora is a benign and beautiful sign that something electric is happening in the space around Earth. Named for the Roman goddess of dawn, auroras are Earth's biggest light show. Auroras appear most often in skies above Earth's polar regions -- hence the name Northern and Southern Lights.

Auroras occur when high-energy electrons from the magnetosphere are guided by Earth's magnetic field toward the polar regions and the atmosphere. There, they collide with oxygen and nitrogen, electrically exciting these gases so that they emit light, much like the glow of a fluorescent lamp.


Auroras form between 60 and 250 miles above Earth's surface. How powerful is a magnetic storm?
Magnetic Storms Rip Through Earth's Magnetosphere

Aurora and MoonGreen Aurora
Magnetic storms occur when a CME hits Earth's magnetosphere. Magnetic storms...
+ Generate million amp electric currents that distort the magnetosphere and flow down into our upper atmosphere
+ Disturb the Van Allen radiation belts, which become filled with "killer electrons" that can pierce the skin of a satellite and the cells of an astronaut
+ Cause spectacular, widespread auroras, even at low latitudes
+ Damage power systems on Earth and interfere with broadcasting
1989 Aurora
Aurora Rings the Poles
From the ground, the aurora looks like curtains of light. But photographs from space show us that the aurora is shaped like a giant, oval ring. Actually, two rings: there's a crown of light around each of Earth's magnetic poles.
Most of the high-energy, electrically-charged particles in Earth's atmosphere are trapped in two doughnut-shaped belts surrounding Earth: the Van Allen radiation belts. These belts of dangerous particles were the first major discovery of the Space Age.

Radiation Belts



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Last Modified: 1/20/2000 TMV