Van Allen Belts and Aurorae

Charged particles experience a force when they move through a magnetic field. This is how a television works. An electron gun fires a beam of electrons, a cathode ray, and electromagnets direct the beam to fall on the screen and build up a picture.

With a strong enough beam you can get charged particles to move in circles, trapped in a magnetic bottle.

Van Allen Belts

In 1958 Dr. James van Allen proved the existence of belts of charged particles trapped by the Earth's magnetic field. The particles, mostly protons and electrons, may originally come from the Sun. They now bounce back and forth from pole to pole in two belts as shown below. The outer belt extending to about 24,000 km. The belts are actually doughnut shaped.

The charged particles are dangerous to astronauts (fast moving electrons are beta radiation). However astronauts are exposed to a huge amount of radiation anyway when they go into space, mostly from the Sun. The belts can interfere with the delicate equipment in satellites.

How could astronauts be protected from the harmful effects of space radiation?

Aurorae

The aurora borealis are otherwise known as the northern lights. It is now understood that theses are caused by charged particles from the solar wind striking the atmosphere and making the molecules they hit emit light.

The Sun emits a huge amount of charged particles all the time, this is the solar wind. These particles take about 2 days to reach Earth. When they do they are deflected by the Earth's magnetic field and many particles enter the atmosphere at the poles.

In what countries might you see the aurora borealis?

pic   NASA 

The aurora australis occurs close to the south pole.