NSF PR 98-10 - February 17, 1998
This material is available primarily for archival
purposes. Telephone numbers or other contact information
may be out of date; please see current contact information
at media
contacts.
Scientists Seek First Glimpse of Solar Features during
February 26 Solar Eclipse
Scientists from several research institutes will aim
new detectors at the sun's corona during the February
26 solar eclipse, searching for structures they've
never before observed. The researchers are funded
in part by the National Science Foundation (NSF),
and are from several research institutes, including
the National Center for Atmospheric Research (NCAR)
in Boulder, Colorado. The scientists will use NSF's
C-130 Hercules aircraft to conduct many of their studies.
This eclipse, which takes place in totality over the
Caribbean, promises to be one of the most heavily
studied in recent history. The data scientists gather
could lead to better prediction of the coronal mass
ejections that launch solar storms -- the magnetic
disturbances that play havoc with communications and
electric power grids here on earth. The expedition
to be conducted in late February has been inspired
by new theories and new technology, the researchers
say.
The corona, or outer atmosphere of the sun, is a million
times dimmer than the solar disk itself. Scientists
can observe the corona at any time using a coronagraph
-- an instrument that blacks out the disk -- but sunlight
scattered by earth's atmosphere masks the very faint
coronal light. A "real" eclipse gives much better
results, because the moon blocks sunlight before it
reaches the earth's atmosphere and is scattered.
Solar physicists can't send instruments too close
to their subject because its heat would melt their
probes. In spite of that, however, the structure of
the magnetic fields of the corona has been theorized
since the late 1800s. These fields, while weak, are
sufficiently strong that they underlie and organize
everything that happens in the corona.
"Nobody has actually measured the strength of the
magnetic field under average coronal conditions, because
it's so weak," explains NCAR solar physicist Philip
Judge. Because of the faint signal, exacting observations
must be made with minimal interference from the earth's
atmosphere. Detection instruments mounted on the C-130
aircraft will enable scientists to make the needed
measurements, as the aircraft can fly above most of
the absorption introduced by water vapor into the
earth's atmosphere.
Detection of the magnetic field's signal could build
the case for constructing a measuring device called
a coronal magnetograph. The kinds of questions that
could then be addressed include the nature of the
evolution of coronal fields during the solar cycle,
and what launches solar flares and the coronal mass
ejections that cause disrupting "space weather." The
late February effort is a first step, maintains Judge.
"We won't really know what's going on in the corona,
until we can measure the magnetic field."
A new infrared camera will also make its debut on
the C-130. The camera's infrared array detector was
recently declassified for peacetime use. It will be
used to detect interplanetary dust particles, invisible
to sensors so far. The glare of the sun normally obscures
such infrared emissions, so an eclipse is a rare opportunity
to look for this dust with new technology.
Editors: Visuals are available from Zhenya Gallon
at NCAR at (303) 497-8607, zhenya@ucar.edu.
|