New twists to the inside story of the Sun
11 Dec 2001At a conference in San Francisco last night, scientists using the ESA-NASA SOHO spacecraft to probe the solar interior reported surprising new details about what goes on beneath the dark sunspots that blemish the Sun's bright face. What was previously thought to be a single broad tube of hot, strongly magnetized gas, rising towards the surface beneath a spot, turns out on closer examination to be many smaller magnetic structures that rise quickly from deep within the Sun.
And the rotation of a sunspot at the surface has been traced to a strong vortex of gas beneath the surface. Rotating sunspots are often associated with violent magnetic explosions affecting the Earth, so detecting such hidden gas flows in future may provide a way of predicting surface outbursts.
"These discoveries are showing us that the Sun's interior is much more complex and dynamic than we thought,", said Philip Scherrer of Stanford University who is in charge of the MDI instrument on SOHO, which registers sound waves coming from the interior at a million points on the surface. "Understanding violent solar activity, which is driven by turbulence within the Sun, will be more challenging."
SOHO is a project of international cooperation between ESA and NASA. The spacecraft was built in Europe for ESA and equipped with instruments by teams of scientists in Europe and the USA. NASA launched SOHO in December 1995, and in 1998 ESA and NASA decided to extend its highly successful operations until 2003.