Definition
Dark, relatively cooler regions on the surface of the sun caused by intense localized magnetic activity. Sunspots appear in cycles averaging about 11 years and are associated with increased solar flare activity, which disturbs the Earth's ionosphere and disrupts high-frequency (HF) radio communications and navigation signals.
Plain English
Dark patches on the sun caused by strong magnetic activity. They come and go in a roughly 11-year cycle, and when there are lots of them, they can mess with long-range radio signals on Earth.
Context Anchor
Seen in aviation weather and space-weather discussions, especially when long-range communication, satellite navigation, or radio reception may be affected.
Why Pilots Care
High sunspot activity can trigger radio blackouts on HF frequencies and reduce GPS accuracy, directly affecting communication and navigation on oceanic or remote routes.
Intuition Check
Sunspots are not dirt, shadows, or weather on the Sun. In aviation, the important point is that they are signs of solar activity that can affect signals reaching aircraft.
Example Sentence 1
Increased sunspot activity that week disrupted HF communications, forcing the crew to rely on satellite voice for their oceanic crossing.
Example Sentence 2
After a major solar flare linked to sunspots, the aircraft lost HF contact for nearly twenty minutes.