Posted: Wed, Nov 7, 2001, 4:07 PM ET (2107 GMT)
Solar scientists said Tuesday that they now have a better understanding of the structure of sunspots and how they stay together, thanks to data from the ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft. Data from a SOHO instrument allowed scientists to probe the region below the surface of a sunspot, giving an unprecedented view of the structure of these features. Sunspots form in regions where the Sun's magnetic field becomes concentrated; the field pinches off the flow of energy from lower regions, causing the surface to cool and darken. Scientists found that as the plasma on surface cools, it becomes denser and eventually falls at speeds of up to 5,000 km/h. This draws in surrounding plasma, which also cools and falls, setting up a cycle that persists as long as the magnetic field in the region is strong. The SOHO observations also showed that sunspots are relatively shallow, extending no more than about 5,000 km below the photosphere, or visible surface of the Sun.

Related Links:

•  NASA press release
•  ESA press release
•  BBC article