- Top: sunspot region 2192 during the
partial solar eclipse in 2014
 and in September 2011.
- Middle: sunspot close-up in the visible spectrum (left) and in
UV, taken by the
- Bottom: A large group of sunspots stretching about 320,000 km (200,000 mi) across.
Sunspots are temporary
phenomena on the
photosphere that appear as spots darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of
magnetic field flux that inhibit
convection. Sunspots usually appear in pairs of opposite magnetic
 Their number varies according to the approximately 11-year
Individual sunspots or groups of sunspots may last anywhere from a few days to a few months, but eventually decay. Sunspots expand and contract as they move across the surface of the Sun, with diameters ranging from 16 km (10 mi)
 to 160,000 km (100,000 mi).
 The larger variety are visible from Earth without the aid of a
 They may travel at
relative speeds, or
proper motions, of a few hundred meters per second when they first emerge.
Indicating intense magnetic activity, sunspots accompany secondary phenomena such as
reconnection events. Most
solar flares and
coronal mass ejections originate in magnetically active regions around visible sunspot groupings. Similar phenomena indirectly observed on
stars other than the Sun are commonly called
starspots, and both light and dark spots have been measured.