英语听力：自然百科 地球力场 Earth's Force Field—1（在线收听） |
The solar system is a hostile place. Earth is under attack from deadly cosmic radiation. Life here is only possible, because it's protected by the magnetosphere, an invisible force field that cocoons the planet. But new evidence reveals that this vital shield is weakening. A region above the South Atlantic is experiencing dangerous levels of radiation. Is earth losing its magnetic shield? “It's not a matter of if the earth's magnetic field will disappear someday. it's a matter of when.”
And what will happen to life if it does?
Like a giant umbrella, Earth's magnetosphere shields us from the steady stream of cosmic radiation that fills our solar system. Exposure to this is deadly.
“The magnetic field coming out from the Earth makes a big bubble around the Earth，the magnetosphere that protects us from the most violent actions of the sun.”
Many of the charged particles in the solar wind have enough energy so that they would represent a hazard to human beings if they made direct contact with the surface environment.
If you're on the path of these oncoming charged particles zipping out from the sun, if you're not inside some shield, you're dead.
Without the magnetosphere, all life is vulnerable to these high-energy cosmic particles. They penetrate living tissue and cause severe damage to cells.
“As the field becomes weaker and weaker, the effects of space radiation will be felt at lower and lower and progressively lower altitudes, so possibly one outcome of a reduced magnetic field would be through increased exposure to radiation, higher rates of cancer among populations.” |
| 原文地址：http://www.tingroom.com/lesson/zrbaike/2011/259933.html |