a cooler darker spot appearing periodically on the sun's photosphere; associated with a strong magnetic field
双语例句
Galileo was the first person to see mountains on the moon and sunspots on the sun. 伽里略是看到月球上山脉和太阳黑子的第一人。
Normally the number of sunspots peaks every 11 years, coinciding with the times when the sun's magnetic field is at its strongest. 一般来说，太阳黑子的数量每十一年达到一次顶峰，正巧和太阳磁场最强的周期一致。
