英语听力:自然百科 地球力场 Earth's Force Field—3(在线收听) |
In polar regions where the magnetic field is / weakest, auroras glow in the sky. These dazzling displays of colored lights form when solar particles slam into gases in our atmosphere causing them to glow. The stronger the solar wind, the more dramatic the auroras. Although beautiful, there is a sign of the ferocious battle between our magnetosphere and the invading stream of solar radiation. You know magnetic field , face-on radiation all across the planet. But scientists have made an alarming discovery: face-on radiation is hitting earth. Out here in the Atlantic Ocean, just off the coast of Brazil, sits a region with a rapidly weakening magnetic field. It’s known as the South Atlantic Anomaly. It’s around 3 million square miles and growing. Everyday, cosmic radiation reaches closer to the earth’s surface. We don’t fully understand the origin of this anomaly, but the consequences could be dire. NASA's scientists monitor the anomaly’s impact on technology.
The combination of the energetic particles found in the South Atlantic Anomaly as well as new particles being ejected there by solar storms, you know, have resulted in many total failures of communication spacecrafts. Satellites can be permanently damaged when they pass over the anomaly. Vital instruments on the billion-dollar Hubble space telescope have to be shut down for protection when it enters the area. As the magnetic field continues to weaken over the South Atlantic, radiation is reaching increasingly lower altitudes, and could start to affect more than just technology. Professor Peter Alson believes air passengers would be the first to the risk.
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原文地址:http://www.tingroom.com/lesson/zrbaike/2011/259935.html |