sunspot
/ˈsʌnspɒt/noun
- Astronomy a spot or patch appearing from time to time on the sun's surface, appearing dark by contrast with its surroundings【天文】太阳黑子。
Sunspots are regions of lower surface temperature and are believed to form where loops in the sun's magnetic field intersect the surface; an individual spot may persist for several weeks. The number of sunspots on the solar surface fluctuates according to a regular cycle, with times of maximum sunspot activity recurring every eleven years.