The last geomagnetic reversal for Earth was about 780,000 years ago.
地球上最后一次地磁倒转大约是78万年前。
We don't really know why but we have some theories that are being borne out in mathematical models.
除了有一些以数学模型来证实的理论以外，我们的确不知道地磁倒转的原因。
We also know that the magnetic field of the sun reverses as well every 11 years, whereas the Earth's reverses irregularly.
我们还知道太阳的磁场也发生倒转——每们年一次，而地球磁场的倒转并无规律。
Although magnetic reversals have occurred many times in the geologic past, it is not yet possible to predict when the next reversal will occur.
尽管在过去地质时期地磁场发生了多次倒转，但要预测下次倒转将在何时发生也还是不可能的。
Our research may also eventually learn more about the causes of changes and reversals of Earth's magnetic field.
我们的研究也会最终了解更多的有关地球磁场变化和倒转的知识。
We know from magnetic records locked in rocks that the Earth's magnetic field has reversed many times in the past.
我们从锁定在岩石中的磁记录中知道，地球磁场在过去倒转了很多次。
The historic reversal rate for Earth seems to be once every few hundred thousand years, but it has varied widely;
地球L地磁历史性的倒转似乎是每几十万年一次，但它的变化范围很大；
This paper introduces the formation of magnetic field, polarity reversal, secular variation and the use of geomagnetic polarity reversal or susceptibility in stratigraphic study.
本文介绍了地球磁场的成因、极性变化以及运用极性倒转划分对比地层和指示环境。
The time between magnetic reversals on the Earth is sometimes as short as 10,000 years and sometimes as long as 25 million years;
地球上的磁倒转之间的时间，短的有时候为1万年，长的有时候可达2500万年；
This reversal process can be seen in the pale magnetic record, locked into rocks of the ocean floor and in some lava flows.
这个倒转过程能在古地磁记录中看到，这些记录被锁定在海底的岩石里和一些熔岩流中。
In addition, the computer model has produced three spontaneous reversals of the geomagnetic field during the 300,000-year simulation.
此外，计算机模型已经在30万年的模拟过程中产生了三次地磁场的自发倒转。
The stochastic nature of the process probably explains why the time between reversals on the Earth varies so much.
这个过程的随机性特征可能解释为什么地球磁场倒转之间的间隔变化会如此之大。
No one can say with any certainty whether this represents a fluctuation or whether it is a decrease, which will eventually lead to a reversal.
没有人能够确定地说出这是否会代表将最终导致倒转的磁场波动或减退。
Occasionally, however, the dipole part of the field reverses, causing the locations of the north and south magnetic poles to switch.
不过，有时候磁场的偶极部分会倒转，导致了北磁极和南磁极的位置转换。
The act of inverting.
倒置，倒转颠倒的动作
It was twirled round and round till it was nearly twirled out of the ground.
靶子不住地旋转，直到它几乎转倒在地上。
The reversal process is not literally periodic as it is on the sun, whose magnetic field reverses every 11 years.
倒转过程不是真正具有像在太阳上那样的周期性，太阳磁场每11年出现倒转。
One that inverts or produces inversion.
倒转者倒转者或产生倒转者