Sunspot

Sunspots are temporary spots on the <a href="/facts/Sun%2527s_surface/32a139LB">Sun's surface</a> that are darker than the surrounding area. They are one of the most recognizable <a href="/facts/Solar_phenomena/28AnjNfE">Solar phenomena</a> and despite the fact that they are mostly visible in the <a href="/facts/Solar_photosphere/CadPCVHh">solar photosphere</a> they usually affect the entire <a href="/facts/Solar_atmosphere/CadPCVHh">solar atmosphere</a>. They are regions of reduced surface temperature caused by concentrations of <a href="/facts/Magnetic_flux/jQMVxrnD">magnetic flux</a> that inhibit <a href="/facts/Convection/E8vsCPhu">convection</a>. Sunspots appear within <a href="/facts/Active_region/7E8cWSGl">active regions</a>, usually in pairs of opposite <a href="/facts/Magnetic_polarity/vvrg6VSk">magnetic polarity</a>. Their number varies according to the approximately 11-year <a href="/facts/Solar_cycle/QrP4Egea">solar cycle</a>.
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). Larger sunspots can be visible from Earth without the aid of a <a href="/facts/Telescope/BDwYahhR">telescope</a>. They may travel at <a href="/facts/Relative_speed/bVyzQ02h">relative speeds</a>, or <a href="/facts/Proper_motion/ECByRQ8c">proper motions</a>, of a few hundred meters per second when they first emerge.
Indicating intense magnetic activity, sunspots accompany other active region phenomena such as <a href="/facts/Coronal_loop/v3b2m7BK">coronal loops</a>, <a href="/facts/Solar_prominence/ShLDJjCn">prominences</a>, and <a href="/facts/Magnetic_reconnection/0FeHqFkE">reconnection</a> events. Most <a href="/facts/Solar_flare/6kCvPKxD">solar flares</a> and <a href="/facts/Coronal_mass_ejection/YxbMGrkS">coronal mass ejections</a> originate in these magnetically active regions around visible sunspot groupings. Similar phenomena indirectly observed on <a href="/facts/Star/PFbd6ICx">stars</a> other than the Sun are commonly called <a href="/facts/Starspot/Hc16g7mJ">starspots</a>, and both light and dark spots have been measured.

Sunspot open-in-new

Sunspot