The phrase "large sunspot" refers to a dark and cooler area on the surface of the sun that appears bigger than usual.
Sentences with «large sunspot»
This ultraviolet image of the sun shows large sunspot group AR 9169 as the bright area near the horizon. (space.com)
And the time lapse between the appearance of large sunspots and aurora borealis at relatively low latitudes is about five days. (scientificamerican.com)
[Related: Largest Sunspot in 24 Years Wows Scientists, But Also Mystifies] (space.com)