|Earth is a Giant Magnet
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 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.
|How high are auroras?
||A magnetic storm produces about a million megawatts of electricity, enough to power the United States.
||Magnetic Storms Rip Through Earth's Magnetosphere
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
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.