The
STEREO spacecraft shows average activity on the sun.
A
close-up view of the top of the sun seen in profile shows thousands of little
spurts, like small blow torches, shooting out all over the sun.
These
spurts are called "spicules."
The spicules are plasma jets that shoot through the Sun's atmosphere or corona
at about 55,900 miles per hour (90,000 kph). Discovered in 1877 by Angelo
Secchi, they remain largely unexplained, in part because observations are
difficult for these objects with a brief lifespan of about 5 minutes, and the relatively
small diameter of 300 miles (500 kilometers). They are caused by shock waves
formed when sound
waves at the solar surface leak into the solar atmosphere. More than
100,000 spicules occur at any given time on our star's surface.
The
image was taken in extreme ultraviolet light on August 3, 2007.
-- ESA/NASA and SPACE.com Staff
Credit: ESA/NASA
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