Answer:

sunspot

Answer	Crossword Clue
SUNSPOT	On an 11-year cycle
SUNSPOT	Dark solar area
SUNSPOT	One may be 50,000 miles in diameter

SUNSPOT	Solar phenomenon
SUNSPOT	Solar "blemish"
SUNSPOT	Solar event caused by magnetic activity
SUNSPOT	Shortwave-reception factor
SUNSPOT	Factor in shortwave reception
SUNSPOT	Solar storm
SUNSPOT	Spectrohelioscope viewing
SUNSPOT	Solar phenomenon.

SUNSPOT	Celestial phenomenon.
SUNSPOT	Freckle
SUNSPOT	Source of disruption to satellites
SUNSPOT	It's got magnetic pull
SUNSPOT	Solar blemish
SUNSPOT	Solar blot
SUNSPOT	Solar dark patch