Geomagnetic activity, the natural variations in Earth's magnetic field, it fluctuates in 11-year cycles.
地磁活动是地球磁场的自然变化，其波动周期为11年。
2
As solar activity waned at the end of one of the Sun's 11-year cycles, the new data shows the amount of light and heat reaching the Earth rose rather than fell.
The sun's internal dynamics were the subject of intense interest over the last few years as the normal waxing and waning of solar activity did not follow past cycles as closely as anticipated.