Carolyn Williams, age 14, of Shreveport, Louisiana, for her question:

  Do we know the cause of the Van Allen Belts?

The Van Allen Belts were discovered by the first satellites sent aloft with the birth of the Space Age, just a few years ago. The first news about them was horri¬fying and even experts thought that these radiation belts would make future space travel impossible. But later investigations disqualified this gloomy prediction. More satellites measured the dimensions of the belts and their shape. These factors plus other data compiled on the ground helped scientists to grasp both the nature and possible cause of the Van Allen Belts.

These enormous regions exist high above the earth and their shapes suggest a relationship with the earth's immense magnetic field. What's more, they are radi¬ation belts of electrically charged particles like those emitted by the sun. The earth's magnetic field loops high above the equator and dips down to the two mag¬netic poles. Scientists suspect that its force attracts and holds clouds of solar particles heading for the earth. It holds them aloft in the Van Allen Belts, acting as an umbrella to shield us from too much solar radiation.