Space is part of everybody's daily lives. Satellites transmit television, telephone and other information around the world, and watch over our changing environment. As it tracks destructive hurricanes on Earth, a satellite might itself be damaged by another kind of storm - one which occurs in space. These magnetic storms disrupt radio communications and have caused electricity blackouts.
Magnetic storms occur in geospace - the comet-like region of Space around the Earth including the magnetosphere. Geospace is big - it's more than a million kilometres long! It is not empty space, there just are not that many particles - if you brought all the particles down to the ground they would fit inside a typical supermarket! But what the particles lack in number they make up for in energy. Some particles zip around geospace at speeds close to the speed of light!
Geospace is where the atmospheres of the Sun and Earth meet. Every second, one thousand tonnes of ionised matter flow out from the Sun into space. This outflow is called the solar wind and hurtles past the Earth's magnetosphere at hundreds of kilometres per second! As it brushes past the magnetosphere's boundary it causes the ionised particles there to move along with it, like a breeze blowing over a wheat field moves the ears of wheat. Just as the movement of the ears of wheat at the top of the wheat stalk causes the stalk to bend and to move at all levels down to the ground, so too does the whole of geospace adjust to the motion at its boundary. In geospace magnetic field lines act like the wheat stalks, connecting the motions hundreds of thousands of kilometres away in space to winds just a hundred kilometres above the Earth's surface. Not only do ionised particles move with the magnetic field lines but they also move along them. As they rain down magnetic field lines towards the Earth they can collide with other neutral particles and emit a light called the AURORA. Since most of the magnetic field lines are rooted near the northern and southern magnetic poles, the aurora and the other effects of geospace are concentrated here.
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