Coronal Hole
Explanation:
This ominous, dark shape sprawling across the face of the
active Sun is a
coronal
hole -- a low density region extending above
the surface
where the solar magnetic field opens freely into
interplanetary space.
Studied extensively
from
space since the 1960s in
ultraviolet
and
x-ray light,
coronal holes are known to be the source of
the high-speed
solar wind, atoms and electrons
which flow outward along the open
magnetic field lines.
During periods of low activity,
coronal
holes typically cover
regions just above the Sun's poles.
But
this coronal hole, one of the largest seen
so far in the current
solar
activity cycle, extends from
the south pole (bottom) well into northern hemisphere.
Coronal holes
like this one may last for a few solar rotations
before the magnetic fields shift and change configurations.
Shown in false-color, this picture of the Sun on January 8th
was made in extreme ultraviolet light by the
EIT
instrument on board the space-based SOHO observatory.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
