Heating Coronal Loops
Extending above the photosphere or visible surface of
the Sun, the faint,
tenuous solar corona can't be easily seen
from Earth, but it is
measured to be hundreds of times hotter than the photosphere itself.
What makes
the solar corona so hot?
Astronomers have long
sought the source of the corona's heat in
magnetic
fields which loft monstrous loops of
solar
plasma above the photosphere.
Still,
new and
dramatically
detailed observations
of
coronal loops from
the orbiting
TRACE satellite are now pointing more closely to the
unidentified energy source.
Recorded in extreme ultraviolet light,
this
and other TRACE images
indicate that most of the heating occurs low in the corona, near the
bases of the loops as they emerge from and return to the solar
surface.
The new results confound the
conventional theory which relies on heating the loops uniformly.
This tantalizing TRACE image shows
clusters of the
majestic, hot coronal loops which span 30 or more
times the diameter of planet Earth.