DISCOVERY OF THE VAN ALLEN BELTS
Until 1958, scientists believed that space above our atmosphere was basically featureless. But that was before we started exploring space.
When the first US satellite,Explorer was launched, it measured small levels of radiation coming from the sun and outer space. But within minutes, as the spacecraft flew upward, radiation began to skyrocket. Soon it overwhelmed Explorers instruments. Scientists thought that the counter measuring the radiation had broken. But as the satellite descended, the radiation count fell too.
The intensity of particles had in-creased from 30 particles per second to over 45,0001 Dr. James Van Allen, who designed and built the radiation counter, studied the data. He concluded that the earth's magnetic field loops outward into space, trapping countless energetic particles. Later, as other space probes went farther into space, scientists discovered that radiation levels rise, decrease, and then rise again before dropping to a constant tower level—the solar wind. With this information, Van Allen made one of the most astounding maps in modern science. It showed two huge doughnut-shaped belts, one within the other, encircling the earth. Dr. James Van Allen and the Explorer satellite that first detected the radiation belts surrounding the earth in 1958
Recent findings have determined that the inner belt is made mainly of high-energy protons. These charged particles come from the radioactive decay of neutrons released from gas atoms in the earth's exosphere by cos-mic ray bombardment. The outer belt is mainly high energy electrons along with an always changing mixture of other ions from the solar wind and the earth's atmosphere.
So why was the discovery of the Van Allen belts important? It showed that certain areas of space are deadly to humans. Even rugged electronic instruments in satellites and space probes can't survive long there. It also showed how the earth acts like a colossal Iron magnet. In a complex, dynamic process, charged particles from the sun and earth Interact with the earth's magnetic force to form these two strange belts. As the solar winds whip around the belts, particles get trapped within the powerful magnetic fields. The particles spiral around for a few hours up to many years. Some make their way to the earth's atmosphere, and others weave back into space.
Space scientists are still working to understand this region known as the magnetosphere. Physicists have sent dozens of instruments into the magnetospheres of Earth and other planets.They have found some interesting things. Only planets with a magnetic field have these belts, and none of them are quite like the earth's. Jupiter's magnetosphere, for example, is one hundred times larger than the earth's. From the earth, Jupiter would look larger than the moon if we could see its magnetosphere. One fact is dear—God has shielded the earth and its living things from the sun's devastating radiation.